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  • 551  (71)
  • 04. Solid Earth::04.04. Geology::04.04.09. Structural geology  (16)
  • 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy  (16)
  • 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas  (10)
  • Springer-Verlag  (85)
  • Geological Society of America  (19)
  • MDPI Publishing
  • Nature Publishing Group
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  • 1
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    Fluid/rock interaction and mass transfer in continental subduction zones: constraints from trace elements and isotopes (Li, B, O, Sr, Nd, Pb) in UHP rocks from the Chinese Continental Scientific Drilling Program, Sulu, East China (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: In order to better understand the role of fluids during subduction and subsequent exhumation, we have investigated whole-rock and mineral chemistry (major and trace elements) and Li, B as well as O, Sr, Nd, Pb isotopes on selected continuous drill-core profiles through contrasting lithological boundaries from the Chinese Continental Scientific Drilling Program (CCSD) in Sulu, China. Four carefully selected sample sets have been chosen to investigate geochemical changes as a result of fluid mobilization during dehydration, peak metamorphism, and exhumation of deeply subducted continental crust. Our data reveal that while O and Sr-Nd-Pb isotopic compositions remain more or less unchanged, significant Li and/or B isotope fractionations occur between different lithologies that are in close contact during various metamorphic stages. Samples that are supposed to represent prograde dehydration as indicated by veins formed at high pressures (HP) are characterized by element patterns of highly fluid-mobile elements in the veins that are complementary to those of the host eclogite. A second sample set represents a UHP metamorphic crustal eclogite that is separated from a garnet peridotite by a thin transitional interface. Garnet peridotite and eclogite are characterized by a 〉10% difference in MgO, which, together with the presence of abundant hydroxyl-bearing minerals and compositionally different clinopyroxene grains demonstrate that both rocks have been derived from different sources that have been tectonically juxtaposed during subduction, and that hydrous silicate-rich fluids have been added from the subducting slab to the mantle. Two additional sample sets, comprising retrograde amphibolite and relatively fresh eclogite, demonstrate that besides external fluids, internal fluids can be responsible for the formation of amphibolite. Li and B concentrations and isotopic compositions point to losses and isotopic fractionation during progressive dehydration. On the other hand, fluids with isotopically heavier Li and B are added during retrogression. On a small scale, mantle-derived rocks may be significantly metasomatized by fluids derived from the subducted slab. Our study indicates that during high-grade metamorphism, Li and B may show different patterns of enrichment and of isotopic fractionation.
    Keywords: Fluid/rock interaction; Elemental transfer; Isotopic fractionation; Subduction and exhumation; Sulu ; 551 ; Earth Sciences; Mineralogy; Mineral Resources; Geology
    Language: English
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  • 2
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    The Itajaí foreland basin: a tectono-sedimentary record of the Ediacaran period, Southern Brazil (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The Itajaí Basin located in the southern border of the Luís Alves Microplate is considered as a peripheral foreland basin related to the Dom Feliciano Belt. It presents an excellent record of the Ediacaran period, and its upper parts display the best Brazilian example of Precambrian turbiditic deposits. The basal succession of Itajaí Group is represented by sandstones and conglomerates (Baú Formation) deposited in alluvial and deltaic-fan systems. The marine upper sequences correspond to the Ribeirão Carvalho (channelized and non-channelized proximal silty-argillaceous rhythmic turbidites), Ribeirão Neisse (arkosic sandstones and siltites), and Ribeirão do Bode (distal silty turbidites) formations. The Apiúna Formation felsic volcanic rocks crosscut the sedimentary succession. The Cambrian Subida leucosyenogranite represents the last felsic magmatic activity to affect the Itajaí Basin. The Brusque Group and the Florianópolis Batholith are proposed as source areas for the sediments of the upper sequence. For the lower continental units the source areas are the Santa Catarina, São Miguel and Camboriú complexes. The lack of any oceanic crust in the Itajaí Basin suggests that the marine units were deposited in a restricted, internal sea. The sedimentation started around 600 Ma and ended before 560 Ma as indicated by the emplacement of rhyolitic domes. The Itajaí Basin is temporally and tectonically correlated with the Camaquã Basin in Rio Grande do Sul and the Arroyo del Soldado/Piriápolis Basin in Uruguay. It also has several tectono-sedimentary characteristics in common with the African-equivalent Nama Basin.
    Keywords: Dom Feliciano Belt; Ediacaran; Foreland basin; U–Pb SHRIMP ages; Provenance ; 551 ; Earth Sciences; Geophysics/Geodesy; Geology
    Language: English
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  • 3
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    Petrographical and petrophysical properties of sandstones: statistical analysis as an approach to predict material behaviour and construction suitability (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: Most studies dealing with material properties of sandstones are based on a small data set. The present study utilizes petrographical and petrophysical data from 22 selected sandstones and ~300 sandstones from the literature to estimate/predict the material and weathering behaviour of characteristic sandstones. Composition and fabric properties were determined from detailed thin section analyses. Statistical methods applied consist of data distributions with whisker plots and linear regression with confidence regions for the petrophysical and weathering properties. To identify similarities between individual sandstones and to define groups of specific sandstone types, principal component and cluster analyses were applied. The results confirm an interaction between the composition, depositional environment, stratigraphic association and diagenesis, which leads to a particular material behaviour of sandstones. Three different types of pore radii distributions are observed, whereby each is derived from different pore space modifications during diagenesis and is associated with specific sandstone types: (1) bimodal with a maximum in capillary and micropores, (2) unimodal unequal with a maximum in smaller capillary pores and (3) unimodal equable with a maximum in larger capillary pores. Each distribution shows specific dependencies to water absorption, salt loading and hygric dilatation. The strength–porosity relationship shows dependence on the content of unstable lithic fragments, grain contact and type of pore radii distribution, cementation and degree of alteration. Sandstones showing a maximum of capillary pores and micropores (bimodal) exhibit a distinct hygric dilatation and low salt resistance. These sandstones are highly immature sublitharenites–litharenites, characterized by altered unstable rock fragments, which show pointed-elongated grain contacts, and some pseudomatrix. Quartz arenites and sublitharenites–litharenites which are strongly compacted and cemented, show unimodal unequal pore radii distributions, low porosity, high strength and a high salt resistance. The presence of swellable clay minerals in sublitharenites–litharenites leads to a medium to high hygric dilatation, whereas quartz arenites show little hygric dilatation. Sandstones with unimodal equal pore radii distribution mostly belong to weakly compacted and cemented mature quartz arenites. These are characterized by high water absorption and high porosity, low to medium strength and a low salt resistance. The data compiled in this study are used to create a sandstone quality catalogue. Since material properties are dependent on many different parameters of influence, the transition between different lithotypes is fluent.
    Keywords: Sandstones; Pore space; Prediction; Weathering behavior; Compressive strength ; 551 ; Earth Sciences; Geology
    Language: English
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  • 4
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    Lattice-preferred orientations of late-Variscan granitoids derived from neutron diffraction data: implications for magma emplacement mechanisms (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The lattice-preferred orientation (LPOs) of two late-Variscan granitoids, the Meissen monzonite and the Podlesí dyke granite, were determined from high-resolution time-of-flight neutron diffraction patterns gained at the diffractometer SKAT in Dubna, Russia. The results demonstrate that the method is suitable for the LPO analysis of polyphase, relatively coarse-grained (0.1–6 mm) rocks. The Meissen monzonite has a prominent shape-preferred orientation (SPO) of the non-equidimensional minerals feldspar, mica and amphibole, whereas SPO of the Podlesí granite is unapparent at the hand-specimen scale. The neutron diffraction data revealed distinct LPOs in both granitoids. The LPO of the non-equidimensional minerals feldspar, mica and amphibole developed mainly during magmatic flow. In the case of the Meissen monzonite, the magmatic flow was superimposed by regional shear tectonics, which, however, had no significant effect on the LPOs. In both samples, quartz shows a weak but distinct LPO, which is atypical for plastic deformation and different in the syn-kinematic Meissen monzonite and the post-kinematic Podlesí granite. We suggest that, first of all, the quartz LPO of the Meissen monzonite is the result of oriented growth in an anisotropic stress field. The quartz LPO of the Podlesí granite, which more or less resembles a deformational LPO in the flattening field of the local strain field, developed during magmatic flow, whereby the rhombohedral faces of the quartz crystals adhered to the (010) faces of aligned albite and to the (001) faces of zinnwaldite. Due to shape anisotropy of their attachments, the quartz crystals were passively aligned by magmatic flow. Thus, magmatic flow and oriented crystal growth are the major LPO-forming processes in both granitoids. For the Meissen monzonite, the solid-state flow was too weak to cause significant crystallographic re-orientation of the minerals aligned by magmatic flow. Finally, the significance of our results for the evaluation of the regional tectonic environment during magma emplacement is discussed. The discussion on the regional implications of the more methodologically oriented results provides the basis for future, more regionally aimed studies in view of the fabric characteristics of such plutons and their developing mechanisms.
    Keywords: Neutron diffraction; Lattice-preferred orientation; Shape-preferred orientation; Magmatic flow; Podlesí granite; Meissen Massif ; 551 ; Earth Sciences; Geology; Geophysics/Geodesy
    Language: English
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  • 5
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    The Neoproterozoic-early Paleozoic metamorphic and magmatic evolution of the Eastern Sierras Pampeanas: an overview (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The Eastern Sierras Pampeanas were structured by three main events: the Ediacaran to early Cambrian (580–510 Ma) Pampean, the late Cambrian–Ordovician (500–440 Ma) Famatinian and the Devonian-Carboniferous (400–350 Ma) Achalian orogenies. Geochronological and Sm–Nd isotopic evidence combined with petrological and structural features allow to speculate for a major rift event (Ediacaran) dividing into two Mesoproterozoic major crustal blocks (source of the Grenvillian age peaks in the metaclastic rocks).This event would be coeval with the development of arc magmatism along the eastern margin of the eastern block. Closure of this eastern margin led to a Cambrian active margin (Sierra Norte arc) along the western margin of the eastern block in which magmatism reworked the same crustal block. Consumption of a ridge segment (input of OIB signature mafic magmas) which controlled granulite-facies metamorphism led to a final collision (Pampean orogeny) with the western Mesoprotrozoic block. Sm–Nd results for the metamorphic basement suggest that the TDM age interval of 1.8–1.7 Ga, which is associated with the less radiogenic values of εNd(540) (−6 to −8), can be considered as the mean average crustal composition for the Eastern Sierras Pampeanas. Increasing metamorphic grade in rocks with similar detrital sources and metamorphic ages like in the Sierras de Córdoba is associated with a younger TDM age and a more positive εNd(540) value. Pampean pre-540 Ma granitoids form two clusters, one with TDM ages between 2.0 and 1.75 Ga and another between 1.6 and 1.5 Ga. Pampean post-540 Ma granitoids exhibit more homogenous TDM ages ranging from 2.0 to 1.75 Ga. Ordovician re-activation of active margin along the western part of the block that collided in the Cambrian led to arc magmatism (Famatinian orogeny) and related ensialic back-arc basin in which high-grade metamorphism is related to mid-crustal felsic plutonism and mafic magmatism with significant contamination of continental crust. TDM values for the Ordovician Famatinian granitoids define a main interval of 1.8–1.6, except for the Ordovician TTG suites of the Sierras de Córdoba, which show younger TDM ages ranging from 1.3 to 1.0 Ga. In Devonian times (Achalian orogeny), a new subduction regime installed west of the Eastern Sierras Pampeanas. Devonian magmatism in the Sierras exhibit process of mixing/assimilation of depleted mantle signature melts and continental crust. Achalian magmatism exhibits more radiogenic εNd(540) values that range between 0.5 and −4 and TDM ages younger than 1.3 Ga. In pre-Devonian times, crustal reworking is dominant, whereas processes during Devonian times involved different geochemical and isotopic signatures that reflect a major input of juvenile magmatism.
    Keywords: Magmatism-metamorphism; Sm–Nd systematics; Tectonic evolution; Neoproterozoic-early Paleozoic orogenies; Eastern Sierras Pampeanas ; 551 ; Earth Sciences; Geophysics/Geodesy; Geology
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  • 6
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    Moisture expansion as a deterioration factor for sandstone used in buildings (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The expansion processes that develop in building stones upon changes of moisture content may be an important contributing factor for their deteriorations. Until recently, few data could be found in the literature concerning this parameter and weathering processes. Moreover, the processes that may be responsible for the moisture related expansion of natural building stones are not yet completely understood. To further elucidate this process, extensive mineralogical, petrophysical and fabric investigations were performed on eight German sandstones in order to obtain more information regarding the weathering process and its dependence on the rock fabric. The analysed sandstones show a wide range of pore size distributions and porosities. A positive correlation with the fabric and the pore space can be found for all studied petrophysical parameters. The intensity of the expansion and related swelling pressure cannot be attributed only to the swelling of clay minerals. The investigations suggest that the micropores and the resulting disjoining pressure during wet/dry cycles also play an important role. The results obtained suggest that the mechanism is related to the presence of liquid water within the porous material.
    Keywords: Sandstone weathering; Moisture expansion; Hygric and hydric wetting; Swelling clay minerals ; 551 ; Earth Sciences; Geology
    Language: English
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  • 7
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    Optimized extraction of dimension stone blocks (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The profitable production of dimension stone mainly depends on the extractable block size. The regularity and volume of the blocks are of critical importance, and are controlled by the three-dimensional pattern of the discontinuity system. Therefore, optimization of block size has to be the aim when quarrying for natural stone. This is mainly connected to the quantification of joints and fractures, i.e., their spacing and orientation. The problem of finding unfractured blocks within arbitrarily oriented and distributed planes can be solved effectively by a numerical algorithm. The main effects of joint orientations on block sizes and shapes will be presented in this article. Quantification of unfractured blocks with the aim of optimization is illustrated by detailed studies on several quarries. The algorithm used in this study can be applied as a powerful tool in the planning of a quarry and the future exploitation of dimension stone. Application of the described approach is demonstrated on practical examples of quarrying natural stones, namely, sandstone, granite, rhyolite, etc. Block quarrying can be optimized by using the new 3D-BlockExpert approach. The quantification of unfractured rock masses is also shown to contribute to a more ecological protection and the sustainable use of natural resources.
    Keywords: Production of dimension stones; Joints and fractures; Block sizes; Optimization ; 551 ; Earth Sciences; Geology
    Language: English
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  • 8
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    Physical weathering of building stones induced by freeze–thaw action: a laboratory long-term study (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: Damages to natural building stones induced by the action of frost are considered to be of great importance. Commonly, the frost resistance of building stones is checked by standardised freeze–thaw tests before using. Corresponding tests normally involve 30–50 freeze–thaw action cycles. In order to verify the significance of such measurements, we performed long-term tests on four selected rocks over 1,400 freeze–thaw action cycles. Additionally, numerous petrophysical parameters were analysed to compare the behaviour of rocks in the weathering tests according to the current explanatory models of stress formation by growing ice crystals in the pore space. The long-term tests yield more information about the real frost sensibility of the rocks. A clear deterioration cannot be determined in most cases until 50 weathering cycles have been completed. In the freeze–thaw tests, the samples are also stressed by changing temperature and moisture, indicating that different decay mechanisms can interfere with each other. Thus, thermohygric and moisture expansion are important damage processes.
    Keywords: Freeze–thaw action; Natural building stones; Microfabric; Pore space properties ; 551 ; Earth Sciences; Geology
    Language: English
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  • 9
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    Quality assessment of replacement stones for the Cologne Cathedral: mineralogical and petrophysical requirements (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: Owing to its long building history, different types of building stones comprised the construction of the Cologne Cathedral. Severe damage is observed on the different stones, e.g., sandstones, carbonate, and volcanic rocks, especially when the different stone materials neighbor the medieval “Drachenfels trachyte” from the “Siebengebirge”. The question arises, “Is the insufficient compatibility of the implemented building materials causatively related to the strong decay of the Drachenfels trachyte?” The present investigations focus on the petrography and mineralogical composition of eight different stones from the Cologne Cathedral. Petrophysical data, i.e., phase content, moisture and thermal characteristics as well as strength properties are determined and discussed in correlation to each other, showing that not only in terms of lithology great differences exist, but also the petrophysical properties strongly diverge. The ascertained parameters are discussed in view of the deterioration behavior and decay mechanisms of the different stones. To evaluate the compatibility of original, replacement and modern building materials, the properties of the investigated stones are compared to those of Drachenfels trachyte by means of constraints given in the literature. Besides optical properties, petrophysical criteria are also defined as well as strength values. It could be shown that primarily moisture properties, i.e., capillary and sorptive water uptake, water saturation, drying processes and moisture dilatation can be addressed to the deterioration processes.
    Keywords: Stone decay; Cologne Cathedral; Compatibility of building materials; Requirements for replacement stones ; 551 ; Earth Sciences; Geology
    Language: English
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  • 10
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    Traces of the bone-eating annelid Osedax in Oligocene whale teeth and fish bones (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-04-27
    Description: The range of substrates that the bone-eating marine worm Osedax is able to consume has important implications for its evolutionary history, especially its potential link to the rise of whales. Once considered a whale specialist, recent work indicates that Osedax consumes a wide range of vertebrate remains, including whale soft tissue and the bones of mammals, birds and fishes. Traces resembling those produced by living Osedax have now been recognized for the first time in Oligocene whale teeth and fish bones from deep-water strata of the Makah, Pysht and Lincoln Creek formations in western Washington State, USA. The specimens were acid etched from concretions, and details of the borehole morphology were investigated using micro-computed tomography. Together with previously published Osedax traces from this area, our results show that by Oligocene time Osedax was able to colonize the same range of vertebrate remains that it consumes today and had a similar diversity of root morphologies. This supports the view that a generalist ability to exploit vertebrate bones may be an ancestral trait of Osedax.
    Keywords: Deep-sea; Trace fossil; Osedax; Whale; Fish; Micro-CT; Tiefsee; Spurenfossil; Osedax; Wal; Fisch; Micro-CT ; 551 ; Earth Sciences; Paleontology
    Language: English
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  • 11
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    Propagation, linkage, and interaction of caldera ring-faults: comparison between analogue experiments and caldera collapse at Miyakejima, Japan, in 2000 (2018)
    Springer-Verlag | Springer-Verlag
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    Publication Date: 2021-03-29
    Description: The formation of ring faults yields important implications for understanding the structural and dynamic evolution of collapse calderas and potentially associated ash-flow eruptions. Caldera collapse occurred in 2000 at Miyakejima Island (Japan) in response to a lateral intrusion. Based on geophysical data it is inferred that a set of caldera ring faults was propagating upward. To understand the kinematics of ring-fault propagation, linkage, and interaction, we describe new laboratory sand-box experiments that were analyzed through Digital Image Correlation (DIC) and post-processed using 2D strain analysis. The results help us gain a better understanding of the processes occurring during caldera subsidence at Miyakejima. We show that magma chamber evacuation induces strain localization at the lateral chamber margin in the form of a set of reverse faults that sequentially develops and propagates upwards. Then a set of normal faults initiates from tension fractures at the surface, propagating downwards to link with the reverse faults at depth. With increasing amounts of subsidence, interaction between the reverse- and normal-fault segments results in a deactivation of the reverse faults, while displacement becomes focused on the outer normal faults. Modeling results show that the area of faulting and collapse migrates successively outward, as peak displacement transfers from the inner ring faults to later developed outer ring faults. The final structural architecture of the faults bounding the subsiding piston-like block is hence a consequence of the amount of subsidence, in agreement with other caldera structures observed in nature. The experimental simulations provide an analogy to the observations and seismic records of caldera collapse at Miyakejima volcano, but are also applicable to caldera collapse in general.
    Keywords: Collapse calderas; Ring faults; Analogue modeling; Fault kinematics; Digital image correlation ; 551 ; Earth Sciences; Sedimentology ; Mineralogy ; Geophysics/Geodesy ; Geology
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  • 12
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    Proximate causes of deforestation in the Bolivian lowlands: an analysis of spatial dynamics (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: Forests in lowland Bolivia suffer from severe deforestation caused by different types of agents and land use activities. We identify three major proximate causes of deforestation. The largest share of deforestation is attributable to the expansion of mechanized agriculture, followed by cattle ranching and small-scale agriculture. We utilize a spatially explicit multinomial logit model to analyze the determinants of each of these proximate causes of deforestation between 1992 and 2004. We substantiate the quantitative insights with a qualitative analysis of historical processes that have shaped land use patterns in the Bolivian lowlands to date. Our results suggest that the expansion of mechanized agriculture occurs mainly in response to good access to export markets, fertile soil, and intermediate rainfall conditions. Increases in small-scale agriculture are mainly associated with a humid climate, fertile soil, and proximity to local markets. Forest conversion into pastures for cattle ranching occurs mostly irrespective of environmental determinants and can mainly be explained by access to local markets. Land use restrictions, such as protected areas, seem to prevent the expansion of mechanized agriculture but have little impact on the expansion of small-scale agriculture and cattle ranching. The analysis of future deforestation trends reveals possible hotspots of future expansion for each proximate cause and specifically highlights the possible opening of new frontiers for deforestation due to mechanized agriculture. Whereas the quantitative analysis effectively elucidates the spatial patterns of recent agricultural expansion, the interpretation of long-term historic drivers reveals that the timing and quantity of forest conversion are often triggered by political interventions and historical legacies.
    Keywords: Bolivia; Amazon; Deforestation; Proximate causes; Spatial analysis; Multinomial logistic regression ; 551 ; Environment; Geology; Geography (general); Regional/Spatial Science; Climate Change; Nature Conservation; Oceanography
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  • 13
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    Monument futures: climate change, air pollution, decay and conservation—the Wolf-Dieter Grimm-volume (2018)
    Springer-Verlag | Springer-Verlag
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    Publication Date: 2021-03-29
    Keywords: 551 ; Geosciences; Geology
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  • 14
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    Major shear zones of southern Brazil and Uruguay: escape tectonics in the eastern border of Rio de La plata and Paranapanema cratons during the Western Gondwana amalgamation (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The Mantiqueira Province represents a series of supracrustal segments of the South-American counterpart formed during the Gondwana Supercontinent agglutination. In this crustal domain, the process of escape tectonics played a conspicuous role, generating important NE–N–S-trending lineaments. The oblique component of the motions of the colliding tectonic blocks defined the transpressional character of the main suture zones: Lancinha-Itariri, Cubatão-Arcádia-Areal, Serrinha-Rio Palmital in the Ribeira Belt and Sierra Ballena-Major Gercino in the Dom Feliciano Belt. The process as a whole lasted for ca. 60 Ma, since the initial collision phase until the lateral escape phase predominantly marked by dextral and subordinate sinistral transpressional shear zones. In the Dom Feliciano Belt, southern Brazil and Uruguay, transpressional event at 630–600 Ma is recognized and in the Ribeira Belt, despite less coevally, the transpressional event occurred between 590 and 560 Ma in its northern-central portion and between ca. 625 and 595 Ma in its central-southern portion. The kinematics of several shear zones with simultaneous movement in opposite directions at their terminations is explained by the sinuosity of these lineaments in relation to a predominantly continuous westward compression.
    Keywords: Mantiqueira Province; Gondwana agglutination; Suture zones; Escape tectonics; Metamorphic-deformational events ; 551 ; Earth Sciences; Geophysics/Geodesy; Geology
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  • 15
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    Exhumation and uplift of the Sierras Pampeanas: preliminary implications from K–Ar fault gouge dating and low-T thermochronology in the Sierra de Comechingones (Argentina) (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The Sierras Pampeanas in central and north-western Argentina constitute a distinct morphotectonic feature between 27°S and 33°S. The last stage of uplift and deformation in this area are interpreted to be closely related to the Andean flat-slab subduction of the Nazca plate beneath the South American plate. K–Ar fault gouge dating and low-temperature thermochronology along two transects within the Sierra de Comechingones reveal a minimum age for the onset of brittle deformation about 340 Ma, very low exhumation rates since Late Paleozoic time, as well as a total exhumation of about 2.3 km since the Late Cretaceous. New Ar–Ar ages (7.54–1.91 Ma) of volcanic rocks from the San Luis volcanic belt support the eastward propagation of the flat-slab magmatic front, confirming the onset of flat-slab related deformation in this region at 11.2 Ma. Although low-temperature thermochronology does not clearly constrain the signal of the Andean uplift, it is understood that the current structural relief related to the Comechingones range has been achieved after the exhumation of both fault walls (circa 80–70 Ma).
    Keywords: Sierras Pampeanas; K–Ar dating; Fault gouge dating; Low thermal geochronology; Andean uplift ; 551 ; Earth Sciences; Geophysics/Geodesy; Geology
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  • 16
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    Short-term fluctuations in vegetation and phytoplankton during the Middle Eocene greenhouse climate: a 640-kyr record from the Messel oil shale (Germany) (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The Palaeogene was the most recent greenhouse period on Earth. Especially for the Late Palaeocene and Early Eocene, several superimposed short-term hyperthermal events have been described, including extremes such as the Palaeocene–Eocene Thermal Maximum. Major faunal and floral turnovers in the marine and terrestrial realms were recorded in association with these events. High-resolution palynological analysis of the early Middle Eocene maar lake sediments at Messel, near Darmstadt, Germany, provides an insight into the dynamics of a climax vegetation during the Middle Eocene greenhouse climate in a time span without significant climatic excursions. Numerical techniques like detrended correspondence analysis and wavelet analysis have been applied to recognize cyclic fluctuations and long-term trends in the vegetation through a time interval of approximately 640 kyr. Based on the numerical zoning of the pollen diagram, three phases in the development of the vegetation may be distinguished. Throughout these phases, the climax vegetation did not change substantially in qualitative composition, but a trend towards noticeably less humid conditions probably in combination with a drop of the water level in the lake may be recognized. A shift in algal population from the freshwater dinoflagellate cyst Messelodinium thielepfeifferae to a dominance of Botryococcus in the uppermost part of the core is interpreted as a response to changes in acidity and nutrient availability within the lake. Time series analyses of pollen assemblages show that variations in the Milankovitch range of eccentricity, obliquity and precession can be distinguished. In addition, fluctuations in the sub-Milankovitch range are indicated. This demonstrates that floral changes during steady depositional conditions in the Middle Eocene of Messel were controlled by orbital forcing.
    Keywords: Middle Eocene; Maar lake; Palynology; Climate variability; Milankovitch cycles; Multivariate statistics; Time series analysis ; 551 ; Earth Sciences; Geology; Geophysics/Geodesy
    Language: English
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    Microbial diversity on a marble monument: a case study (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: In the presented case study, ascomycete fungi and green algae on a marble monument were identified by comparisons of the 18S rRNA gene sequences, which were obtained from DNA either from environmental samples or from enrichment cultures. The organisms were found to be responsible for either black or green surface coverings on different areas of the monument surface. Most fungi were related to plant-inhabiting genera, corresponding to a heavy soiling of the marble surface with honeydew. Whereas green algae of the genera Stichococcus, Chloroidium and Apatococcus were found to be dominant in all samples, isolates of two additional genera were recovered only from enrichment cultures. A reference strain of Apatococcus lobatus and an isolate of Prasiolopsis sp. were investigated with respect to putative surface adhesive structures of the cell envelope. The Prasiolopsis cell walls were covered with a thin adhesive exopolysaccharide layer involved in biofilm formation.
    Keywords: Marble monument; Biofilm; Ascomycete fungi; Green algae; Cell wall; Exopolysaccharide ; 551 ; Earth Sciences; Geology
    Language: English
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    Bowing of dimensional granitic stones (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: Bowing is a well-known phenomenon seen in marbles used as building veneers. This form of rock weathering occurs as a result of external factors such as temperature, humidity, the system for anchoring the marble slabs or the panel dimensions. Under the same external conditions, many factors will determine the degree of deformation including petrography, thermal properties and residual locked stresses. The usual way to solve the problem of bowed marble slabs is to replace them with other materials, such as granites, in which the deformation still exists but is less common. In this study, eight ornamental granites with different mineralogy, grain size, grain shape, porosity and fabric were tested in a laboratory to assess their susceptibility to bowing. Three slabs of granite, each cut with a different orientation, were studied under different conditions of temperature (90 and 120°C) and water saturation (dry and wet) to investigate the influence of these factors together with that of anisotropy. At 90°C, only the granite with the coarsest grain size and low porosity exhibited deformation under wet conditions. At 120°C and wet conditions, three of the granites showed evident signs of bowing. Again, the granite with the coarsest grain size was the most deformed. It was concluded that the wide grain size distribution influences microcracking more than other expected factors, such as the quartz content of the rock. Also, mineral shape-preferred orientation and porosity play an important role in the bowing of the studied granites.
    Keywords: Granitoids; Bowing; Texture; Thermal expansion ; 551 ; Earth Sciences; Geology
    Language: English
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    Multi-stage emplacement of the Götemar Pluton, SE Sweden: new evidence inferred from field observations and microfabric analysis, including cathodoluminescence microscopy (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The emplacement of the Mesoproterozoic Götemar Pluton into Paleoproterozoic granitoid host rocks of the Transscandinavian Igneous Belt is re-examined by microfabric analysis, including cathodoluminescence microscopy. Field data on the pluton-host rock system are used to strengthen the model. The Götemar Pluton, situated on the Baltic Shield of SE Sweden, is a horizontally zoned tabular structure that was constructed by the intrusion of successive pulses of magma with different crystal/melt ratios, at an estimated crustal depth of 4–8 km. Initial pluton formation involved magma ascent along a vertical dike, which was arrested at a mechanical discontinuity within the granitoid host rocks; this led to the formation of an initial sill. Subsequent sill stacking and their constant inflation resulted in deformation and reheating of existing magma bodies, which also raised the pluton roof. This multi-stage emplacement scenario is indicated by complex dike relationships and the occurrence of several generations of quartz (Si-metasomatism). The sills were charged by different domains of a heterogeneous magma chamber with varying crystal/melt ratios. Ascent or emplacement of magma with a high crystal/melt ratio is indicated by syn-magmatic deformation of phenocrysts. Complex crystallization fabrics (e.g. oscillatory growth zoning caused by high crystal defect density, overgrowth and replacement features, resorbed and corroded crystal cores, rapakivi structure) are mostly related to processes within the main chamber, that is repeated magma mixing or water influx.
    Keywords: Pluton emplacement; Microfabrics; Cathodoluminescence; Mesoproterozoic; Götemar; SE Sweden ; 551 ; Earth Sciences; Geophysics/Geodesy; Geology
    Language: English
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    Provenance of Pleistocene Rhine River Middle Terrace sands between the Swiss–German border and Cologne based on U–Pb detrital zircon ages (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Keywords: Provenance; Heavy minerals; Detrital zircon; U–Pb dating; Rhine River; Alps ; 551 ; Earth Sciences; Geology; Geophysics/Geodesy
    Language: English
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    Localisation and temporal variability of groundwater discharge into the Dead Sea using thermal satellite data (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Keywords: Landsat ETM+; Sea surface temperature; Submarine groundwater discharge; Groundwater resource ; 551 ; Earth Sciences; Geology
    Language: English
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    Dolomitic slates from Uruguay: petrophysical and petromechanical characterization and deposit evaluation (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: Slates are internationally known as roof and façade-cladding material since prehistoric times. The methods required to mine and manufacture these dimensional stones are relatively simple in comparison to those utilized in granitic dimensional stones. This has led to a worldwide rentable commercialization of slate in the last centuries and also to the development of characteristic cultural landscapes. In Uruguay several slates are mined and used in architecture, especially as façade cladding and floor slabs. The most important slates regarding their production and utilization are the dolomitic slates. These dolomitic slates are associated with the Neoproterozoic thrust and fold belt of the Dom Feliciano belt. Representative samples have been geochemically and petrographically characterized, as well as petrophysically and petromechanically analyzed. The petrophysical and petromechanical properties were investigated in a very systematic way with respect to the new European standards, showing values comparable to those registered for internationally known slates. Detailed structural and deposit analysis were carried out in Uruguay in order to evaluate the dolomitic slate deposits. The slates are linked to calc-silicate strata in a greenschist facies volcano-sedimentary sequence and the deposits are located in the limb of a regional fold, where bedding and cleavage are parallel. The main lithotype is a layered and fine-grained dolomitic slate with a quite diverse palette of colors: light and dark green, gray, dark gray, reddish and black. The mined slate is split into slabs 0.5–2 cm thick. In the past, the average production in Uruguay was around 4,000 tons/year and a historical maximum of 13,000 tons was reached in 1993 (Oyhantçabal et al. in Z dt Ges Geowiss 158(3):417–428, 2007). The oscillations in the regional demand were the cause of several flourishing and decay cycles in the activity, but our investigation shows a considerable volume of indicated resources and therefore a very good potential.
    Keywords: Slates; Dimensional stones; Petrophysical properties; Petrography; Uruguay ; 551 ; Earth Sciences; Geology
    Language: English
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    Microcracking in calcite and dolomite marble: microstructural influences and effects on properties (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: Microstructure‐based finite-element analysis with a microcracking algorithm was used to simulate an actual degradation phenomenon of marble structures, i.e., microcracking. Both microcrack initiation and crack propagation were characterized, as were their dependence on lattice preferred orientation (LPO), grain shape preferred orientation (SPO), grain size, marble composition (calcite and dolomite) and grain‐boundary fracture toughness. Two LPOs were analyzed: a random orientation distribution function and an orientation distribution function with strong directional crystalline texture generated from a March–Dollase distribution. Three SPOs were considered: equiaxed grains; elongated grains and a mixture of equiaxed and elongated grains. Three different grain sizes were considered: fine grains of order 200 μm (only calcitic marble); medium size grains of order 1 mm (calcitic and dolomitic marbles); and large grains of order 2 mm (only dolomitic marble). The fracture surface energy for the grain boundaries, γig, was chosen to be 20 and 40 % of the fracture surface energy of a grain, γxtal, so that both intergranular and transgranular fracture were possible. Studies were performed on these idealized marble microstructures to elucidate the range of microcracking responses. Simulations were performed for both heating and cooling by 50 °C in steps of 1 °C. Microcracking results were correlated with the thermoelastic responses, which are indicators related to degradation. The results indicate that certain combinations of LPO, SPO, grain size, grain‐boundary fracture toughness and marble composition have a significant influence on the thermal-elastic response of marble. Microstructure with the smallest grain size and the highest degree of SPO and LPO had less of a tendency to microcrack. Additionally, with increasing SPO and LPO microcracking becomes more spatially anisotropic. A significant observation for all microstructures was an asymmetry in microcracking upon heating and cooling: more microcracking was observed upon cooling than upon heating. Given an identical microstructure and crystallographic texture, calcite showed larger thermal stresses than dolomite, had an earlier onset of microcracking upon heating and cooling, and a greater microcracked area at a given temperature differential. Thermal expansion coefficients with and without microcracking were also determined.
    Keywords: Marble; Microcracking; Finite-element modeling; Lattice preferred orientation; Shape preferred orientation; Strain energy density; Maximum principal stress; Thermal expansion coefficient; Thermal expansion anisotropy ; 551 ; Earth Sciences; Geology
    Language: English
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    Granitic dimensional stones in Uruguay: evaluation and assessment of potential resources (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: In Uruguay commercial granite varieties comprise mafic rocks, granitoids, and syenitoids. There is a long tradition in Uruguay, as well as worldwide, of using dimensional stones in architecture and art, specially granitic ones. Some of the present applications of these dimensional stones are as façade cladding, countertops, and outdoor and indoor floor slabs. The color spectrum of the Uruguayan granitic dimensional stones varies from black to light gray, covering a wide variety of red and pink and minor greenish-gray. The décor of these granitic dimensional stones is mainly determined by their fabric, fundamentally the grain size and the color distribution between the different minerals that compose the rocks. In the present research the most important commercial granites were sampled to analyze their petrography and petrophysical properties. A detailed structural analysis has been performed in several deposits, as well as the application of the software 3D Block Expert for modeling the possible raw block size distribution. Other factors controlling the mining viability of the deposits were also studied (e.g., homogeneity/heterogeneity of color and décor) and the possible reserves were calculated.
    Keywords: Granitic dimensional stones; Petrophysical properties; Petrography; Deposit characterization; Uruguay ; 551 ; Earth Sciences; Geology
    Language: English
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    Moisture expansion associated to secondary porosity: an example of the Loseros Tuff of Guanajuato, Mexico (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The old mining city of Guanajuato in middle Mexico preserves one of the most important historical legacies in colonial buildings, the UNESCO declared the city World Heritage Site in 1988. Practically all the colonial constructions were built with natural stones from the neighbourhood, of which stands a greenish to reddish vulcanite, called Loseros Tuff. Although the Loseros Tuff is widely used in historical buildings in the city. It shows significant deterioration and weathering effects, principally in the parts where the tuff shows a coarse grain size. The petrographic, petrophysical, mineralogical and geochemical properties of the Loseros Tuff were analysed in order to determine the causes, effects, behaviour and response to deterioration of this volcanic rock. The results of the investigations suggest that in addition to the parameters like the grain size and the porosity properties, the pore radii distribution is decisive for the effectiveness of porosity and the water transport into the rock. It is recognized that once the liquid water invades the rock the dissolution of the matrix occurs, which is accompanied by a sudden moisture expansion favoured by the newly formed secondary porosity and the high content of expandable clay minerals.
    Keywords: Tuff; Moisture expansion; Porosity; Guanajuato ; 551 ; Earth Sciences; Geology
    Language: English
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    Bestimmung der Schadstofffrachten an Kontrollebenen mithilfe von Punktkonzentrationsmessungen und Immissionspumpversuchen – ein Vergleich (2018)
    Springer-Verlag
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    Publication Date: 2021-03-29
    Description: Kurzfassung Die Quantifizierung der Schadstofffrachten an Kontrollebenen ist eine entscheidende Voraussetzung zur Bewertung von Grundwasserschadensfällen und zum Nachweis von Natural Attenuation. Hierzu können zwei verschiedene Erkundungsansätze, die Frachtbestimmung basierend auf der Interpolation von Punktkonzentrationsmessungen sowie Immissionspumpversuche, verwendet werden. Punktkonzentrationsmessungen haben den entscheidenden Nachteil, dass in der Regel nur eine ausreichend große Anzahl sicher stellen kann, dass die gesamte Abstromfahne erfasst wird. Immissionspumpversuche können wiederum relativ hohe Grundwasseraufbereitungs- und Entsorgungskosten verursachen und nur in ausreichend durchlässigen Grundwasserleitern durchgeführt werden. Ein Vergleich der Ergebnisse aus der Anwendung beider Erkundungsansätze kann eine Hilfestellung bei der Konzipierung von Erkundungsmaßnahmen bieten. Daher wurden die Resultate von vier Immissionspumpversuchen mit Messungen in 13, in kurzem Abstand zueinander errichteten, Direct-Push-Messstellen auf dem Gelände eines ehemaligen Gaswerks verglichen. Es konnte festgestellt werden, dass die Vergleichbarkeit der Erkundungsergebnisse je nach Standortsituation stark von der Heterogenität der Verteilung der Schadstoffe im Grundwasserleiter abhängt. Die Studie legt nahe, dass insbesondere bei stark heterogenen Verhältnissen im Grundwasserleiter Immissionspumpversuche bei der Wahl der Erkundungsmethode bevorzugt werden sollten, da die Interpolation von Punktkonzentrationsmessungen selbst im Falle eines relativ engmaschigen Messstellennetzes zu einer großen Erkundungsunsicherheit führen kann.
    Description: The quantification of contaminant mass flow rates at control planes is an essential prerequisite for assessing contaminated sites and for providing evidence of natural attenuation. Two different investigation approaches are usually implemented: mass flow estimation based on interpolation of point scale concentration measurements, and integral pumping tests. Point scale concentration measurements have the crucial disadvantage that in general, only a sufficiently dense monitoring network can ensure that the plume is completely covered. On the other hand, integral pumping tests may require expensive groundwater treatment and disposal and are only applicable in sufficiently conductive aquifers. A comparison of results from the application of both approaches can help with respect to the selection of a subsurface investigation method. A former gasworks site was chosen to compare the results of four integral pumping tests and measurements obtained from 13 direct-push-wells, which were installed at a relatively close spacing. The comparison shows that the correlation of the two methods depends strongly on the heterogeneity of the contaminant distribution within the aquifer. The study suggests that especially in the case of heterogeneous settings, integral pumping tests should be chosen for subsurface investigations, as interpolated point scale concentration measurements, even if densely spaced, can still bear a prohibitively high degree of uncertainty.
    Keywords: contaminant mass flow rate; integral pumping tests; point scale concentration measurements; remediation optimization ; 551 ; Geosciences; Geoecology/Natural Processes; Soil Science & Conservation ; Applied Geosciences ; Waste Water Technology / Water Pollution Control / Water Management / Aquatic Pollution; Hydrogeology
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    Stability assessment of marble statuaries of the Schlossbrücke (Berlin, Germany) based on rock strength measurements and ultrasonic wave velocities (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The degree of weathering in natural stones on buildings and sculptures has been determined for many years in numerous cases by means of ultrasonic measurements. Conclusions concerning the strength of the rock and the type of weathering can thus be drawn. This relationship has not been established for all rock types. Most of the progress utilizing this method has been made in the analysis of marbles, where an increasing degree of weathering shows lower ultrasonic velocities. In the present study, four Carrara marble samples showing similar rock fabrics, but with respect to weathering exhibit considerable differences are investigated. Porosity varies between 0.2 vol. % and ca. 2.4 vol. %, whereby with increasing porosity the pore radii changes as well. Parallel to this the ultrasonic velocities change in dry samples from about 5.5 to 1.6 km/s, respectively. Model calculations reveal that the velocity reduction is caused by cracks with an extremely small aspect ratio of about 0.005 or even less. After a specific loss of strength, however, solution processes can become active, which modify the microcracks and generate an opposite trend. In the process a strong porosity increase correlates to a relatively small velocity reduction. With the presence of water the Vp porosity weathering relationship experiences a considerable modification. Parallel to the reduction of the ultrasonic velocities, it was determined that the mechanical strength (compressive strength, flexural strength, etc.) as well as the static Young’s modulus is reduced almost equally by a progressive advancement of the weathering front. In one case study dealing with tensile strengths, it was clearly documented how tensile cracks develop and propagate in dependence of the rock fabric. The rock mechanical and ultrasonic velocity data were used for stability assessments applied to the marble statuaries from the Schlossbrücke in Berlin. Stability assessments of the sculpture group 4 reveal that some critical parts must be replaced due to safety reasons.
    Keywords: Marble waethering; Mechanical properties; Ultrasonic wave velocites; Stability assessment; Cultural heritage ; 551 ; Earth Sciences; Geology
    Language: English
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    Cambrian sedimentary dykes in the Proterozoic basement of the Västervik area (southeast Sweden): episodic formation inferred from macro- and microfabrics (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: Fabrics of Cambrian sedimentary dykes formed in Proterozoic granites of the Västervik area (Southeast Sweden) evidence repeated opening/filling and mineralisation/cementation events under varying conditions. Diagnostic features include (1) wall-parallel boundaries between epiclastic fillings and (2) early formed dyke sediments that appear as lithoclasts in subsequently formed sedimentary fillings. The psammitic components mostly consist of well-rounded quartz grains related to a coastal environment and fragments from the granitic host rock. Platy calcitic fragments embedded in the epiclastic matrix originally formed as microveins within already-lithified dyke sediments and the adjacent host rock. Convex downward-pointing, internal sagging structures, together with the preferred orientation of compositional boundaries and long axes of grains/rock fragments parallel to the dyke walls, are interpreted as the result of suction-controlled flow of unconsolidated fillings during episodes of downward dyke growth. Pressure solution of quartz grains are evidence of extensional phases with dyke propagation that were interrupted by phases of horizontal compression normal to the dyke walls. The N–S and NE–SW striking sedimentary dykes formed by opening of a pre-existing joint set during NW–SE oriented rifting during the Cambrian.
    Keywords: Sedimentary dykes; Proterozoic; Southeast Sweden; Microfabrics; Passive infill; Cambrian geodynamics ; 551 ; Earth Sciences; Geology; Geophysics/Geodesy
    Language: English
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    Weathering of volcanic tuff rocks caused by moisture expansion (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: Moisture expansion in natural building stones is considered one of the most important factors affecting their weathering and deterioration. The processes that may be responsible for the expansion under determinate relative humidity (hygric dilatation) and water-saturated conditions (hydric dilatation) are generally attributed to the presence of swellable clay minerals. In contrast to this assumption, our investigations show that moisture expansion also takes place in volcanic tuff building stones almost free from clay minerals. To provide a deeper understanding of the processes, swelling and deterioration were performed on 14 volcanic tuffs used as important building stones of different ages, compositions and weathering stages from Mexico, Germany and Hungary. The investigations undertaken include extensive chemical, petrophysical and fabric analyses. The samples show a wide range of effective porosity, microporosity, capillary water absorption, moisture expansion, and CEC values. High moisture expansion does not seem to depend on clay mineral content alone. We also observed that there is no significant effect on dilatation if clay minerals are present but only form a thin coat on the outer shell of bigger pores. Moreover, we identified a correlation between microporosity, average pore radius and moisture expansion. The investigations highlight the fact that moisture expansion cannot only be attributed to swellable clay minerals, and suggest that the presence and accumulation of micropores and their average radius and distribution play an important role for non-clay associated swelling intensity, which can most probably be attributed to the disjoining pressure.
    Keywords: Weathering of tuffs; Hygric expansion; Hydric expansion; Clay mineralogy; Microporosity; Disjoining pressure ; 551 ; Earth Sciences; Geology
    Language: English
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    Discrimination of TiO2 polymorphs in sedimentary and metamorphic rocks (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: Investigation by Raman spectroscopy of samples from different geological settings shows that the occurrence of TiO2 polymorphs other than rutile can hardly be predicted, and furthermore, the occurrence of anatase is more widespread than previously thought. Metamorphic pressure and temperature, together with whole rock chemistry, control the occurrence of anatase, whereas variation of mineral assemblage characteristics and/or fluid occurrence or composition takes influence on anatase trace element characteristics and re-equilibration of relict rutiles. Evaluation of trace element contents obtained by electron microprobe in anatase, brookite, and rutile shows that these vary significantly between the three TiO2 phases. Therefore, on the one hand, an appropriation to source rock type according to Nb and Cr contents, but as well application of thermometry on the basis of Zr contents, would lead to erroneous results if no phase specification is done beforehand. For the elements Cr, V, Fe, and Nb, variation between the polymorphs is systematic and can be used for discrimination on the basis of a linear discriminant analysis. Using phase group means and coefficients of linear discriminants obtained from a compilation of analyses from samples with well-defined phase information together with prior probabilities of groupings from a natural sample compilation, one is able to calculate phase grouping probabilities of any TiO2 analysis containing at least the critical elements Cr, V, Fe, and Nb. An application of this calculation shows that for the appropriation to the phase rutile, a correct-classification rate of 99.5% is obtained. Hence, phase specification by trace elements proves to be a valuable tool besides Raman spectroscopy.
    Keywords: TiO2 polymorph discrimination; Phase classification; Anatase; Brookite; Rutile; Erzgebirge; Zr-in-rutile thermometry ; 551 ; Earth Sciences; Mineral Resources; Mineralogy; Geology
    Language: English
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    The transpressional connection between Dom Feliciano and Kaoko Belts at 580–550 Ma (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: A new U–Pb SHRIMP age of 551 ± 4 Ma on a mylonitic porphyry that intruded into the Sierra Ballena Shear Zone (Southernmost Dom Feliciano Belt, Uruguay) and a review of relevant published data make possible a more refined correlation and reconstruction of Brasiliano/Pan-African transpressional events. Paleogeographic reconstruction, kinematics and timing of events indicate a connection between the shear systems of the Dom Feliciano and Kaoko Belts at 580–550 Ma. Sinistral transpression recorded in shear zones accommodates deformation subsequent to collision between the Congo and Río de la Plata Cratons. The correlation is strengthened by the similarity of magmatic and metamorphic ages in the Coastal Terrane of the Kaoko Belt and the Punta del Este Terrane of the Dom Feliciano Belt. This post-collisional sinistral transpression brought these units near to their final position in Gondwana and explains the different evolution at 550–530 Ma. While in the Kaoko Belt, an extensional episode resulted in exhumation as a consequence of collision in the Damara Belt, in the Dom Feliciano Belt, sinistral transpression occurred associated with the closure of the southern Adamastor Ocean due to Kalahari-Río de la Plata collision.
    Keywords: Dom Feliciano Belt; Kaoko Belt; Brasiliano; Pan-African; Transpressional deformation; Shear Zones ; 551 ; Earth Sciences; Geophysics/Geodesy; Geology
    Language: English
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    Geodynamic evolution of the Eastern Sierras Pampeanas (Central Argentina) based on geochemical, Sm–Nd, Pb–Pb and SHRIMP data (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Keywords: Eastern Sierras Pampeanas; Provenance; Tectonic setting; Gondwana margin; Geodynamic evolution ; 551 ; Earth Sciences; Geophysics/Geodesy; Geology
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    Zircon texture and chemical composition as a guide to magmatic processes and mixing in a granitic environment and coeval volcanic system (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: This study documents the chemical and textural responses of zircon in the Elba igneous complex, with particular reference to the 7- to 7.8-Ma-old Monte Capanne pluton in relation to its coeval volcanic counterpart (Capraia), using BSE imaging and quantitative electron microprobe analyses. The Monte Capanne pluton displays multiple field and geochemical evidence for magma mixing. The samples we have investigated (including monzogranitic, mafic enclave and dyke samples) display similar zircon textures and are associated with an extremely large range of trace and minor element (Hf, Y, HREE, Th, U) compositions, which contrast with relatively simple textures and zoning patterns in zircons from a Capraia dacite. We have used a relatively simple textural classification (patchy zoning, homogenous cores, oscillatory zoning and unzoned zircon) as the basis for discussing the chemical composition and chemical variation within zircons from the Monte Capanne pluton. Based on these data and other works (Dini et al. 2004 in Lithos 78:101–118, 2004) , it is inferred that mixing between metaluminous and peraluminous melts occurred early in the evolution of the Monte Capanne magma chamber. In particular, mixing was responsible for the development of the patchy-zoning texture in the zircon cores, which was associated with reactions between other accessory phases (including monazite, apatite, allanite), which we infer to have significantly affected the Th distribution in zircon. Zircons from the MC pluton displaying “homogeneous cores” have chemical affinities with zircons in the coeval Capraia volcanic system, consistent with the participation of a Capraia-like mantle end-member during mixing. Further zircon growth in the MC pluton produced the oscillatory zoning texture, which records both long-term (crystal fractionation) and transient (recharge with both silicic and mafic magmas) events in a hybrid magma chamber. It is inferred that Hf and the Th/U ratio cannot be used alone to infer magmatic processes due to their dependency on temperature, nor are they a diagnostic feature of xenocrystic grains. This study shows that zircon chemistry coupled with detailed textural analysis can provide a powerful tool to elucidate the complex evolution of a magma system.
    Keywords: Granite petrology; Zircon; Elba; Capraia; Electron microprobe; Magma mixing ; 551 ; Earth Sciences; Mineralogy ; Mineral Resources ; Geology
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    The bowing potential of granitic rocks: rock fabrics, thermal properties and residual strain (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The bowing of natural stone panels is especially known for marble slabs. The bowing of granite is mainly known from tombstones in subtropical humid climate. Field inspections in combination with laboratory investigations with respect to the thermal expansion and the bowing potential was performed on two different granitoids (Cezlak granodiorite and Flossenbürg granite) which differ in the composition and rock fabrics. In addition, to describe and explain the effect of bowing of granitoid facade panels, neutron time-of-flight diffraction was applied to determine residual macro- and microstrain. The measurements were combined with investigations of the crystallographic preferred orientation of quartz and biotite. Both samples show a significant bowing as a function of panel thickness and destination temperature. In comparison to marbles the effect of bowing is more pronounced in granitoids at temperatures of 120°C. The bowing as well as the thermal expansion of the Cezlak sample is also anisotropic with respect to the rock fabrics. A quantitative estimate was performed based on the observed textures. The effect of the locked-in stresses may also have a control on the bowing together with the thermal stresses related to the different volume expansion of the rock-forming minerals.
    Keywords: Granitoids; Bowing; Residual strain; Texture; Thermal expansion ; 551 ; Geosciences; Geology
    Language: English
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    Nd–Sr–Hf–O isotope provinciality in the northernmost Arabian–Nubian Shield: implications for crustal evolution (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: Multi-isotope study including whole-rock Nd–Sr, single zircon Hf, and SIMS δ18O analyses of zircons sheds light on magma sources in the northernmost Arabian–Nubian Shield (ANS) during ~820–570 Ma. Reconnaissance initial Nd and Sr isotope data for the older rocks (~820–740 Ma) reaffirms previous estimates that early crustal evolution in this part of the shield involved some crustal contamination by pre-ANS material. Prominent isotope provinciality is displayed by post-collisional calc-alkaline and alkaline igneous rocks of ~635–570 Ma across a NW-SE transect across basement of the Sinai Peninsula (Egypt) and southern Israel. Silicic rocks of the NW-region are characterized by lower εNd(T)–εHf(T) and higher Sri and δ18O compared with rocks of the SE-region, and the transition between the regions is gradual. Within each region isotope ratios are independent of the extent of magma fractionation, and zircon cores and rims yield similar δ18O values. Comparison with southern segments of the ANS shows that the source for most ~635–570 Ma rocks can be modeled as the isotopically aged lower-intermediate crust in the ANS core (SE-region) and its northern, more contaminated ANS margins (NW-region). Nevertheless, Nd–Sr isotope enrichment of the lithospheric mantle is indicated by some basic magmas of the NW-region displaying the most enriched Nd–Sr isotope compositions. Comparison of Nd and Hf depleted mantle model ages for rocks of the SE-region may indicate that crustal formation events in the ANS geographical core took place at 1.1–1.2 Ga and were followed by crustal differentiation starting at ~0.9 Ga.
    Keywords: Nd–Sr–Hf–O; Arabian–Nubian Shield; Magma-sources; Zircon ; 551 ; Earth Sciences; Mineralogy ; Mineral Resources ; Geology
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    The replacement of plagioclase feldspars by albite: observations from hydrothermal experiments (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: Oligoclase and labradorite crystals have been experimentally replaced by albite in an aqueous sodium silicate solution at 600°C and 2 kbars. The replacement is pseudomorphic and is characterised by a sharp chemical interface which progresses through the feldspar while preserving the crystallographic orientation. Reaction rims of albite, up to 50 μm thick, can be readily achieved within 14 days. Re-equilibration of plagioclase in an 18O-enriched sodium- and silica-bearing solution results in oxygen isotope redistribution within the feldspar framework structure. The observed characteristics of the reaction products are similar to naturally albitised plagioclase and are indicative of an interface-coupled dissolution–reprecipitation mechanism. Chemical analyses demonstrate that the albitisation is accompanied by the mobilisation of major, minor and trace elements also including elements such as Al and Ti which are commonly regarded as immobile during hydrothermal alteration. The results contribute to developing our understanding of the close association between large-scale albitisation and secondary ore mineralisation which is common in nature.
    Keywords: Plagioclase albitisation; Fluid–mineral interaction; Interface-coupled dissolution–reprecipitation; Hydrothermal experiments; Element mobility ; 551 ; Earth Sciences; Mineralogy ; Mineral Resources ; Geology
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    The tectonic significance of K/Ar illite fine-fraction ages from the San Luis Formation (Eastern Sierras Pampeanas, Argentina) (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The Sierra de San Luis forms the southern tip of the Eastern Sierras Pampeanas in central Argentina. Two narrow belts of low-grade phyllites and quartz arenites, i.e. the San Luis Formation, have accommodated part of the strain-related differential exhumation of the medium- to high-grade metamorphic domains that constitute to the basement complex of the sierra. Eleven phyllite samples were subjected to the K/Ar fine-fraction dating technique. Results are interpreted in relation to the Kübler index of the illites, which indicate epimetamorphic conditions for the majority of the samples. Obtained ages between 330 and 290 Ma cover a period of compressional tectonics in the late Mississippian (Visean/Serpukhovian boundary) followed by the subsidence during the formation of the Paganzo Basin in the provinces of La Rioja and San Luis. These tectonic movements are coincident with the Toco orogeny in northern Chile and southern Bolivia. This suggests that the older K/Ar ages document the compressional stage and that younger ages record the cooling of the basement during the subsequent extensional uplift of the basement.
    Keywords: Eastern Sierras Pampeanas; San Luis Formation; Paganzo Basin; K/Ar; Illite fine fractions ; 551 ; Earth Sciences; Geophysics/Geodesy; Geology
    Language: English
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    The Río de la Plata Craton: a review of units, boundaries, ages and isotopic signature (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: A review of the lithostratigraphic units in the Río de la Plata Craton and of new and previously published geochronological, isotopic and geophysical data is presented. Sm–Nd TDM model ages between 2.6 and 2.2 Ga characterize the Piedra Alta Terrane of this craton. Crystallization ages between 2.2 and 2.1 Ga for the metamorphic protoliths and 2.1–2.0 Ga for the post-orogenic granitoids indicate juvenile crust, followed by a short period of crustal recycling. Cratonization of this terrane occurred during the late Paleoproterozoic. Younger overprinting is not observed, suggesting it had a thick and strong lithosphere in the Neoproterozoic. A similar scenario is indicated for the Tandilia Belt of Argentina. Sm–Nd TDM model ages for the Nico Pérez Terrane show two main events of crustal growth (3.0–2.6 and 2.3–1.6 Ga). The crystallization ages on zircon ranges between 3.1 and 0.57 Ga, which is evidence for long-lived crustal reworking. The age for cratonization is still uncertain. In the Taquarembó Block, which is considered the prolongation of the Nico Pérez Terrane in southern Brazil, a similar scenario can be observed. These differences together with contrasting geophysical signatures support the redefinition of the Río de la Plata Craton comprising only the Piedra Alta Terrane and the Tandilia Belt. The Sarandí del Yí Shear Zone is regarded as the eastern margin of this Craton.
    Keywords: Precambrian; Transamazonian cycle; South American platform; Río de la Plata Craton ; 551 ; Earth Sciences; Geophysics/Geodesy; Geology
    Language: English
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    Micro-framework reconstruction from peloidal-dominated mud mounds (Viséan, SW Spain) (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Keywords: Mud mound; Peloids; Automicrites; Micro-framework; Carboniferous; Spain ; 551 ; Earth Sciences; Ecology; Paleontology; Geochemistry ; Biogeosciences; Sedimentology
    Language: English
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    Magma chamber evolution prior to the Campanian Ignimbrite and Neapolitan Yellow Tuff eruptions (Campi Flegrei, Italy) (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Keywords: Campi Flegrei; Phlegraean fields; Campanian Ignimbrite; Neapolitan Yellow Tuff; Geochemistry; Sr and Nd isotopes; Magma batches; Precursor activity ; 551 ; Geosciences; Sedimentology ; Mineralogy ; Geophysics/Geodesy ; Geology
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    Petrology, magnetostratigraphy and geochronology of the Miocene volcaniclastic Tepoztlán Formation: implications for the initiation of the Transmexican Volcanic Belt (Central Mexico) (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The volcaniclastic Tepoztlán Formation (TF) represents an important rock record to unravel the early evolution of the Transmexican Volcanic Belt (TMVB). Here, a depositional model together with a chronostratigraphy of this Formation is presented, based on detailed field observations together with new geochronological, paleomagnetic, and petrological data. The TF consists predominantly of deposits from pyroclastic density currents and extensive epiclastic products such as tuffaceous sandstones, conglomerates and breccias, originating from fluvial and mass flow processes, respectively. Within these sediments fall deposits and lavas are sparsely intercalated. The clastic material is almost exclusively of volcanic origin, ranging in composition from andesite to rhyolite. Thick gravity-driven deposits and large-scale alluvial fan environments document the buildup of steep volcanic edifices. K-Ar and Ar-Ar dates, in addition to eight magnetostratigraphic sections and lithological correlations served to construct a chronostratigraphy for the entire Tepoztlán Formation. Correlation of the 577 m composite magnetostratigraphic section with the Cande and Kent (1995) Geomagnetic Polarity Time Scale (GPTS) suggests that this section represents the time intervall 22.8–18.8 Ma (6Bn.1n-5Er; Aquitanian-Burdigalian, Lower Miocene). This correlation implies a deposition of the TF predating the extensive effusive activity in the TMVB at 12 Ma and is therefore interpreted to represent its initial phase with predominantly explosive activity. Additionally, three subdivisions of the TF were established, according to the dominant mode of deposition: (1) the fluvial dominated Malinalco Member (22.8–22.2 Ma), (2) the volcanic dominated San Andrés Member (22.2–21.3 Ma) and (3) the mass flow dominated Tepozteco Member (21.3–18.8 Ma).
    Keywords: Magnetostratigraphy; K-Ar Geochronology; Volcaniclastics; Miocene; Tepoztlán Formation; Transmexican Volcanic Belt; Central Mexico ; 551 ; Earth Sciences; Sedimentology; Mineralogy; Geophysics/Geodesy; Geology
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    The Sierra Ballena Shear Zone in the southernmost Dom Feliciano Belt (Uruguay): evolution, kinematics, and deformation conditions (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The Sierra Ballena Shear Zone (SBSZ) is part of a high-strain transcurrent system that divides the Neoproterozoic Dom Feliciano Belt of South America into two different domains. The basement on both sides of the SBSZ shows a deformation stage preceding that of the transcurrent deformation recognized as a high temperature mylonitic foliation associated with migmatization. Grain boundary migration and fluid-assisted grain boundary diffusion enhanced by partial melting were the main deformation mechanisms associated with this foliation. Age estimate of this episode is 〉658 Ma. The second stage corresponds to the start of transpressional deformation and the nucleation and development of the SBSZ. During this stage, pure shear dominates the deformation, and is characterized by the development of conjugate dextral and sinistral shear zones and the emplacement of syntectonic granites. This event dates to 658–600 Ma based on the age of these intrusions. The third stage was a second transpressional event at about 586 to 〈560 Ma that was associated with the emplacement of porphyry dikes and granites that show evidence of flattening. Deformation in the SBSZ took place, during the late stages, under regional low-grade conditions, as indicated by the metamorphic paragenesis in the supracrustals of the country rocks. Granitic mylonites show plastic deformation of quartz and brittle behavior of feldspar. A transition from magmatic to solid-state microstructures is also frequently observed in syntectonic granites. Mylonitic porphyries and quartz mylonites resulted from the deformation of alkaline porphyries and quartz veins emplaced in the shear zone. Quartz veins reflect the release of silica associated with the breakdown of feldspar to white mica during the evolution of the granitic mylonites to phyllonites, which resulted in shear zone weakening. Quartz microstructures characteristic of the transition between regime 2 and regime 3, grain boundary migration and incipient recrystallization in feldspar indicate deformation under lower amphibolite to upper greenschist conditions (550–400°C). On the other hand, the mylonitic porphyries display evidence of feldspar recrystallization suggesting magmatic or high-T solid-state deformation during cooling of the dikes.
    Keywords: Brasiliano; Pan-African; Shear zone; Dom Feliciano Belt; Uruguay; Kinematic analysis ; 551 ; Earth Sciences; Geology ; Geophysics/Geodesy
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    Age constraints on faulting and fault reactivation: a multi-chronological approach (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: Movement within the Earth’s upper crust is commonly accommodated by faults or shear zones, ranging in scale from micro-displacements to regional tectonic lineaments. Since faults are active on different time scales and can be repeatedly reactivated, their displacement chronology is difficult to reconstruct. This study represents a multi-geochronological approach to unravel the evolution of an intracontinental fault zone locality along the Danube Fault, central Europe. At the investigated fault locality, ancient motion has produced a cataclastic deformation zone in which the cataclastic material was subjected to hydrothermal alteration and K-feldspar was almost completely replaced by illite and other phyllosilicates. Five different geochronological techniques (zircon Pb-evaporation, K–Ar and Rb–Sr illite, apatite fission track and fluorite (U-Th)/He) have been applied to explore the temporal fault activity. The upper time limit for initiation of faulting is constrained by the crystallization age of the primary rock type (known as “Kristallgranit”) at 325 ± 7 Ma, whereas the K–Ar and Rb–Sr ages of two illite fractions 〈2 μm (266–255 Ma) are interpreted to date fluid infiltration events during the final stage of the cataclastic deformation period. During this time, the “Kristallgranit” was already at or near the Earth’s surface as indicated by the sedimentary record and thermal modelling results of apatite fission track data. (U–Th)/He thermochronology of two single fluorite grains from a fluorite–quartz vein within the fault zone yield Cretaceous ages that clearly postdate their Late-Variscan mineralization age. We propose that later reactivation of the fault caused loss of helium in the fluorites. This assertion is supported by geological evidence, i.e. offsets of Jurassic and Cretaceous sediments along the fault and apatite fission track thermal modelling results are consistent with the prevalence of elevated temperatures (50–80°C) in the fault zone during the Cretaceous.
    Keywords: Argillic alteration; Fault zone; K–Ar illite; Apatite fission track; (U–Th)/He thermochronology ; 551 ; Earth Sciences; Geology ; Geophysics/Geodesy
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    Community forestry management and livelihood development in northwest China: integration of governance, project design, and community participation (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Keywords: Community-based co-management; Community forestry; Livelihood; Governance; Policy; Mechanism; Participation ; 551 ; Environment; Climate Change; Geology; Oceanography; Geography (general); Regional/Spatial Science; Nature Conservation
    Language: English
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    Time constraints on the tectonic evolution of the Eastern Sierras Pampeanas (Central Argentina) (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The application of the SHRIMP U/Pb dating technique to zircon and monazite of different rock types of the Sierras de Córdoba provides an important insight into the metamorphic history of the basement domains. Additional constraints on the Pampean metamorphic episode were gained by Pb/Pb stepwise leaching (PbSL) experiments on two titanite and garnet separates. Results indicate that the metamorphic history recorded by Crd-free gneisses (M2) started in the latest Neoproterozoic/earliest Cambrian (553 and 543 Ma) followed by the M4 metamorphism at ~530 Ma that is documented in the diatexites. Zircon ages of 492 Ma in the San Carlos Massif correlate partly with rather low Th/U ratios (〈0.1) suggesting their growth by metamorphic fluids. This age is even younger than the PbSL titanite ages of 506 Ma. It is suggested that the fluid alteration relates to the beginning of the Famatinien metamorphic cycle in the neighbouring Sierra de San Luis and has not affected the titanite ages. The PTt evolution can be correlated with the plate tectonic processes responsible for the formation of the Pampean orogene, i.e., the accretion of the Pampean basement to the Río de La Plata craton (M2) and the later collision of the Western Pampean basement with the Pampean basement.
    Keywords: Eastern Sierras Pampeanas; Sierras de Córdoba; Pampean and Famatinian cycles; Geodynamic evolution; SHRIMP dating; Titanite and Garnet Pb–Pb step-wise leaching ; 551 ; Earth Sciences; Geology ; Geophysics/Geodesy
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    Indicator Kriging without Order Relation Violations (2018)
    Springer-Verlag | Springer-Verlag
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    Publication Date: 2021-03-29
    Description: Indicator kriging (IK) is a spatial interpolation technique aimed at estimating the conditional cumulative distribution function (ccdf) of a variable at an unsampled location. Obtained results form a discrete approximation to this ccdf, and its corresponding discrete probability density function (cpdf) should be a vector, where each component gives the probability of an occurrence of a class. Therefore, this vector must have positive components summing up to one, like in a composition in the simplex. This suggests a simplicial approach to IK, based on the algebraic-geometric structure of this sample space: simplicial IK actually works with log-odds. Interpolated log-odds can afterwards be easily re-expressed as the desired cpdf or ccdf. An alternative but equivalent approach may also be based on log-likelihoods. Both versions of the method avoid by construction all conventional IK standard drawbacks: estimates are always within the (0,1) interval and present no order-relation problems (either with kriging or co-kriging). Even the modeling of indicator structural functions is clarified.
    Keywords: Aitchison geometry; Ilr coordinates; Indicator variogram; Logistic regression ; 551 ; Geosciences; Hydrogeology ; Geotechnical Engineering; Statistics for Engineering, Physics, Computer Science, Chemistry & Geosciences; Math. Applications in Geosciences
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    Continuum-mechanical, Anisotropic Flow model for polar ice masses, based on an anisotropic Flow Enhancement factor (2018)
    Springer-Verlag | Springer-Verlag
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    Publication Date: 2021-03-29
    Description: A complete theoretical presentation of the Continuum-mechanical, Anisotropic Flow model, based on an anisotropic Flow Enhancement factor (CAFFE model) is given. The CAFFE model is an application of the theory of mixtures with continuous diversity for the case of large polar ice masses in which induced anisotropy occurs. The anisotropic response of the polycrystalline ice is described by a generalization of Glen’s flow law, based on a scalar anisotropic enhancement factor. The enhancement factor depends on the orientation mass density, which is closely related to the orientation distribution function and describes the distribution of grain orientations (fabric). Fabric evolution is governed by the orientation mass balance, which depends on four distinct effects, interpreted as local rigid body rotation, grain rotation, rotation recrystallization (polygonization) and grain boundary migration (migration recrystallization), respectively. It is proven that the flow law of the CAFFE model is truly anisotropic despite the collinearity between the stress deviator and stretching tensors.
    Keywords: Continuum mechanics; Anisotropy; Ice; Mixtures; Recrystallization ; 551 ; Physics; Theoretical and Applied Mechanics; Structural Materials; Engineering Thermodynamics, Heat and Mass Transfer; Classical Continuum Physics
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    Mafic Late Miocene–Quaternary volcanic rocks in the Kamchatka back arc region: implications for subduction geometry and slab history at the Pacific–Aleutian junction (2018)
    Springer-Verlag | Springer-Verlag
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    Publication Date: 2021-03-29
    Description: New 40Ar/39Ar and published 14C ages constrain voluminous mafic volcanism of the Kamchatka back-arc to Miocene (3–6 Ma) and Late Pleistocene to Holocene (〈1 Ma) times. Trace elements and isotopic compositions show that older rocks derived from a depleted mantle through subduction fluid-flux melting (〉20%). Younger rocks form in a back arc by lower melting degrees involving enriched mantle components. The arc front and Central Kamchatka Depression are also underlain by plateau lavas and shield volcanoes of Late Pleistocene age. The focus of these voluminous eruptions thus migrated in time and may be the result of a high fluid flux in a setting where the Emperor seamount subducts and the slab steepens during rollback during terrain accretions. The northern termination of Holocene volcanism locates the edge of the subducting Pacific plate below Kamchatka, a “slab-edge-effect” is not observed in the back arc region.
    Keywords: Kamchatka; Back-arc; Plateau-basalts; Subduction; Trace elements; Isotopes ; 551 ; Earth Sciences; Mineralogy ; Mineral Resources ; Geology
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    The oldest synallactid sea cucumber (Echinodermata: Holothuroidea: Aspidochirotida) (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-04-25
    Description: Aspidochirote holothurian ossicles were discovered in Upper Ordovician-aged Öjlemyr cherts from Gotland, Sweden. The well-preserved material allows definitive assignment to the family Synallactidae, a deep-sea sea cucumber group that is distributed worldwide today. The new taxon Tribrachiodemas ordovicicus gen. et sp. nov. is described, representing the oldest member of the Aspidochirotida. The further fossil record of Synallactidae and evolutionary implications are also discussed.
    Keywords: Echinodermata; Holothuroidea; Ordovician; Sweden; Baltic Sea; Echinodermata; Holothuroidea; Ordovizium; Schweden; Ostsee ; 551 ; Earth Sciences; Paleontology
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    Shear modulus, heat capacity, viscosity and structural relaxation time of Na2O–Al2O3–SiO2 and Na2O–Fe2O3–Al2O3–SiO2 melts (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The configurational heat capacity, shear modulus and shear viscosity of a series of Na2O–Fe2O3–Al2O3–SiO2 melts have been determined as a function of composition. A change in composition dependence of each of the physical properties is observed as Na2O/(Na2O + Al2O3) is decreased, and the peralkaline melts become peraluminous and a new charge-balanced Al-structure appears in the melts. Of special interest are the frequency dependent (1 mHz–1 Hz) measurements of the shear modulus. These forced oscillation measurements determine the lifetimes of Si–O bonds and Na–O bonds in the melt. The lifetime of the Al–O bonds could not, however, be resolved from the mechanical spectrum. Therefore, it appears that the lifetime of Al–O bonds in these melts is similar to that of Si–O bonds with the Al–O relaxation peak being subsumed by the Si–O relaxation peak. The appearance of a new Al-structure in the peraluminous melts also cannot be resolved from the mechanical spectra, although a change in elastic shear modulus is determined as a function of composition. The structural shear-relaxation time of some of these melts is not that which is predicted by the Maxwell equation, but up to 1.5 orders of magnitude faster. Although the configurational heat capacity, density and shear modulus of the melts show a change in trend as a function of composition at the boundary between peralkaline and peraluminous, the deviation in relaxation time from the Maxwell equation occurs in the peralkaline regime. The measured relaxation times for both the very peralkaline melts and the peraluminous melts are identical with the calculated Maxwell relaxation time. As the Maxwell equation was created to describe the timescale of flow of a mono-structure material, a deviation from the prediction would indicate that the structure of the melt is too complex to be described by this simple flow equation. One possibility is that Al-rich channels form and then disappear with decreasing Si/Al, and that the flow is dominated by the lifetime of Si–O bonds in the Al-poor peralkaline melts, and by the lifetime of Al–O bonds in the relatively Si-poor peralkaline and peraluminous melts with a complex flow mechanism occurring in the mid-compositions. This anomalous deviation from the calculated relaxation time appears to be independent of the change in structure expected to occur at the peralkaline/peraluminous boundary due to the lack of charge-balancing cations for the Al-tetrahedra.
    Keywords: Frequency dependent; Shear modulus; Heat capacity; Silicate melts; Relaxation time ; 551 ; Earth Sciences; Mineral Resources ; Geochemistry ; Mineralogy ; Crystallography
    Language: English
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    Grain-Size Control on Petrographic Composition of Sediments: Compositional Regression and Rounded Zeros (2018)
    Springer-Verlag | Springer-Verlag
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    Publication Date: 2021-03-29
    Description: It is well-known that sediment composition strongly depends on grain size. A number of studies have tried to quantify this relationship focusing on the sand fraction, but only very limited data exists covering wider grain size ranges. Geologists have a clear conceptual model of the relation between grain size and sediment petrograpic composition, typically displayed in evolution diagrams. We chose a classical model covering grain sizes from fine gravel to clay, and distinguishing five types of grains (rock fragments, poly- and mono crystalline quartz, feldspar and mica/clay). A compositional linear process is fitted here to a digitized version of this model, by (i) applying classical regression to the set of all pairwise log-ratios of the 5-part composition against grain size, and (ii) looking for the compositions that best approximate the set of estimated parameters, one acting as slope and one as intercept. The method is useful even in the presence of several missing values. The linear fit suggests that the relative influence of the processes controlling the relationship between grain size and sediment composition is constant along most of the grain size spectrum.
    Keywords: Censored data; Compositional Data Analysis; Moore–Penrose generalized inverse; Sedimentary petrography ; 551 ; Earth Sciences; Hydrogeology ; Geotechnical Engineering; Statistics for Engineering, Physics, Computer Science, Chemistry and Earth Sciences; Mathematical Applications in Earth Sciences
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    Geochemical, isotopic and single crystal 40Ar/39Ar age constraints on the evolution of the Cerro Galán ignimbrites (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The giant ignimbrites that erupted from the Cerro Galán caldera complex in the southern Puna of the high Andean plateau are considered to be linked to crustal and mantle melting as a consequence of delamination of gravitationally unstable thickened crust and mantle lithosphere over a steepening subduction zone. Major and trace element analyses of Cerro Galán ignimbrites (68–71% SiO2) that include 75 new analyses can be interpreted as reflecting evolution at three crustal levels. AFC modeling and new fractionation corrected δ18O values from quartz (+7.63–8.85‰) are consistent with the ignimbrite magmas being near 50:50 mixtures of enriched mantle (87Sr/86Sr ~ 0.7055) and crustal melts (87Sr/86Sr near 0.715–0.735). Processes at lower crustal levels are predicated on steep heavy REE patterns (Sm/Yb = 4–7), high Sr contents (〉250 ppm) and very low Nb/Ta (9-5) ratios, which are attributed to amphibolite partial melts mixing with fractionating mantle basalts to produce hybrid melts that rise leaving a gravitationally unstable garnet-bearing residue. Processes at mid crustal levels create large negative Eu anomalies (Eu/Eu* = 0.45–0.70) and variable trace element enrichment in a crystallizing mush zone with a temperature near 800–850°C. The mush zone is repeatedly recharged from depth and partially evacuated into upper crustal magma chambers at times of regional contraction. Crystallinity differences in the ignimbrites are attributed to biotite, zoned plagioclase and other antecrysts entering higher level chambers where variable amounts of near-eutectic crystallization occurs at temperatures as low as 680°C just preceding eruption. 40Ar/39Ar single crystal sanidine weighted mean plateau and isochron ages combined with trace element patterns show that the Galán ignimbrite erupted in more than one batch including a ~ 2.13 Ma intracaldera flow and outflows to the west and north at near 2.09 and 2.06 Ma. Episodic delamination of gravitationally unstable lower crust and mantle lithosphere and injection of basaltic magmas, whose changing chemistry reflects their evolution over a steepening subduction zone, could trigger the eruptions of the Cerro Galán ignimbrites.
    Keywords: Cerro Galán; Puna ignimbrite chemistry; 40Ar/39Ar ages; Delamination; Plateau evolution ; 551 ; Earth Sciences; Sedimentology; Geophysics/Geodesy; Mineralogy; Geology
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    Weathering behaviour and construction suitability of dimension stones from the Drei Gleichen area (Thuringia, Germany) (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The construction suitability of a dimension stone depends on its weathering properties along with the petrology and the petrophysical properties. The aim of this study was to evaluate the suitability of the dimension stones from the “Drei Gleichen” area for construction and replacement purposes. In total, six sandstones (Ingersleben, Wachsenburg, Hindfelden, Seeberg, Röhnberg, Gleichenberg; Upper Triassic) as well as two carbonates (Wachsenburg sinter; Quaternary, Wandersleben dolomite; Middle Triassic) were analysed. The results from our laboratory and on-site studies of the dimension stones show that rocks from the same stratigraphic layer, like the sandstones from the upper Triassic, can show major differences in their petrophysical and weathering properties. These differences are attributed to their different diagenesis, resulting, e.g. in varying pore space, water balance and strength properties. The pore size distribution can be divided into four different groups based on their occurring maxima and micropore content. The determined water balance properties as well as moisture expansion and salt attack depend on these groups. Next to this, the mineralogical composition significantly influences the weathering resistance. Sandstones with a high content of altered lithoclasts show a high amount of moisture expansion, low strength and, in consequence, a low weathering resistance against salt attack. Based on the results of the present study, an evaluation of construction suitability could be accomplished. From the analysed sandstones, only the Seebergen sandstone is suitable for construction purposes due to its good availability, good strength properties (high compressive and tensile strength, low softening degree) as well as a low porosity. Furthermore, the Wachsenburg sandstone also shows good petrophysical and petrological properties, but exploitable deposits are too sparse to be of commercial interest. From the carbonates, the Wachsenburg sinter shows very suitable rock parameters, but only sparse outcrops occur, which are not appropriate for mining.
    Keywords: Dimension stones; Sandstones; Carbonates; Weathering ; 551 ; Earth Sciences; Geology
    Language: English
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    Monuments under threat: environmental impact, preservation strategies and natural stone recourses (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Keywords: 551 ; Earth Sciences; Geology
    Language: English
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    Natural building stones of Mexico–Tenochtitlán: their use, weathering and rock properties at the Templo Mayor, Palace Heras Soto and the Metropolitan Cathedral (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: In the Aztec period and in colonial times different natural stones originating in the Valley of Mexico were used for building construction. Stone weathering was investigated onsite at various historical buildings within the old quarter of Mexico City. In this study, different aspects of weathering and deterioration at three significant historical buildings will be presented, the Aztec excavation site Templo Mayor, the Metropolitan Cathedral, and the colonial palace of the dukes of Heras Soto. Petrophysical properties of the main building stones of these structures were investigated like density, porosity, pore radii distribution, water uptake rate and coefficient, thermal and hygric expansion, and the mechanical properties of uniaxial compressive strength. A relationship between single critical property values, according to anisotropy fabric characteristics, and specific weathering forms could be deduced.
    Keywords: Stone weathering; Mexico-DF; Petrophysical properties; Isotropy–anisotropy; Critical values ; 551 ; Earth Sciences; Geology
    Language: English
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    Late-stage volcano geomorphic evolution of the Pleistocene San Francisco Mountain, Arizona (USA), based on high-resolution DEM analysis and 40Ar/39Ar chronology (2018)
    Springer-Verlag
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    Publication Date: 2021-03-29
    Description: The cone-building volcanic activity and subsequent erosion of San Francisco Mountain, AZ, USA, were studied by using high-resolution digital elevation model (DEM) analysis and new 40Ar/39Ar dating. By defining remnants or planèzes of the volcano flanks in DEM-derived images, the original edifice can be reconstructed. We propose a two-cone model with adjacent summit vents which were active in different times. The reconstructed cones were 4,460 and 4,350 m high a.s.l., corresponding to ∼2,160 and 2,050 m relative height, respectively. New 40Ar/39Ar data allow us to decipher the chronological details of the cone-building activity. We dated the Older and Younger Andesites of the volcano that, according to previous mapping, built the stage 2 and stage 3 stratocones, respectively. The new 40Ar/39Ar plateau ages yielded 589–556 ka for the Older and 514–505 ka for the Younger Andesites, supporting their distinct nature with a possible dormant period between. The obtained ages imply an intense final (≤100 ka long) cone-building activity, terminating ∼100 ka earlier than indicated by previous K-Ar ages. Moreover, 40Ar/39Ar dating constrains the formation of the Inner Basin, an elliptical depression in the center of the volcano initially created by flank collapse. A 530 ka age (with a ±58.4 ka 2σ error) for a post-depression dacite suggests that the collapse event is geochronologically indistinguishable from the termination of the andesitic cone-building activity. According to our DEM analysis, the original cone of San Francisco Mountain had a volume of about 80 km3. Of this volume, ∼7.5 km3 was removed by the flank collapse and subsequent glacial erosion, creating the present-day enlarged Inner Basin, and ∼2 km3 was removed from the outer valleys by erosion. Based on volumetric analysis and previous and new radiometric ages, the average long-term eruption rate of San Francisco Mountain was ∼0.2 km3/ka, which is a medium rate for long-lived stratovolcanoes. However, according to the new 40Ar/39Ar dates for the last ≤100 ka period, the final stratovolcanic activity was characterized by a greater ∼0.3 km3/ka rate.
    Keywords: San Francisco Mountain; DEM analysis; Volcanic geomorphology; 40Ar/39Ar geochronology; Stratovolcanic activity; Erosion; Colorado Plateau ; 551 ; Earth Sciences; Sedimentology; Mineralogy ; Geophysics/Geodesy ; Geology
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    Integrale Quantifizierung von Schadstoffmassenflüssen im Grundwasser – Konditionierung der numerischen Inversion der Konzentrationsganglinien von Immissionspumpversuchen (2018)
    Springer-Verlag | Springer-Verlag
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    Publication Date: 2021-03-29
    Description: Kurzfassung Auf dem Gelände eines ehemaligen Gaswerks (Testfeld Süd) wurden Immissionspumpversuche (IPVs) zur Quantifizierung der Fracht und der mittleren Konzentration gaswerkstypischer Schadstoffe entlang von drei Kontrollquerschnitten durchgeführt. Die daraus resultierenden Konzentrationsganglinien wurden mithilfe des Inversionsprogramms CSTREAM und eines Strömungs- und Transportmodells des hydraulisch extrem heterogenen Grundwasserleiters numerisch ausgewertet. Die den gesamten Abstrombereich der Verdachtsfläche erfassenden Kontrollquerschnitte ermöglichen Aussagen über die Position und Ausbreitung der Schadstofffahne auf dem Gelände des Testfeldes Süd. Bisherige Auswertungen von IPVs konnten die Verteilung der Schadstofffahne um den IPV-Brunnen für genau drei Fälle berechnen: entweder befindet sich die Fahne links vom Brunnen, rechts davon oder ist symmetrisch um ihn verteilt. Um eine realistischere Vorstellung von der Fahnenposition zu ermöglichen, wurden in dieser Studie zusätzlich Direct-Push-Messstellen entlang einer Kontrollebene installiert. Die in diesen Messstellen gemessenen Konzentrationen wurden zur Konditionierung der numerischen Inversionslösung herangezogen. Die Ergebnisse ermöglichen eine genauere Eingrenzung des Fahnenzentrums sowie des Fahnenrandes, was insbesondere die Erarbeitung angepasster und optimierter Sanierungsstrategien unterstützt.
    Description: A series of integral pumping tests (IPTs) were conducted at a former gasworks site to quantify the contaminant mass flux and average concentration in groundwater along three control planes. The resulting concentration-time series were analysed numerically with the help of the inversion code CSTREAM and a flow and transport model representing the highly heterogeneous aquifer. Since the control planes cover the entire downstream width of the potentially contaminated area, they allow conclusions to be drawn about the current location and spread of the contaminant plume. Previous evaluations of integral pumping tests could calculate three scenarios concerning the spread of the plume around the IPT well: (i) the plume is located to the right of the well, (ii) to the left, or (iii) is distributed symmetrically around it. To create a more realistic picture of the plume position, a series of direct-push monitoring wells were installed along one control plane. The concentrations found in these wells were included in the numerical analysis to condition the inversion results, and resulted in a more pronounced plume centre and fringe, which supports the development of optimised remediation strategies.
    Keywords: integral pumping tests; conditioning; plume delineation; remediation optimisation ; 551 ; Geosciences; Geoecology/Natural Processes; Soil Science & Conservation ; Applied Geosciences ; Waste Water Technology / Water Pollution Control / Water Management / Aquatic Pollution; Hydrogeology
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    Structural characteristics of the halite fabric type ‘Kristallbrocken’ from the Zechstein Basin with regard to its development (2018)
    Springer-Verlag | Springer-Verlag
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    Publication Date: 2021-03-29
    Description: The Kristallbrocken are a characteristic centimetre- to decimetre-sized, laminated halite fabric type occurring in the Stassfurt Formation in the Zechstein Basin. Up to now, the nature of the Kristallbrocken, i.e. if they are relics of fine-grained, polycrystalline halite beds or clasts of ‘single crystal-layers’, as well as the deformation mechanisms of this halite type, were not clear from the literature. Drill core material from the salt deposit Teutschenthal at the southern rim of the Zechstein Basin now allowed investigating less intensely deformed samples for the first time. The deformational behaviour of these Kristallbrocken ranges from brittle to ductile, which is evidenced by fractured Kristallbrocken on the one hand and weakly bent or even folded Kristallbrocken on the other hand. Local X-ray texture measurements demonstrated that the Kristallbrocken are definitely single crystals and that they can be regarded as relics of formerly larger ‘single crystal-layers’ of up to several dm2 in size. The folded Kristallbrocken clearly display by their single grain texture characteristics that their crystal lattice is bent, which was most likely enabled by a kind of flexural-shear folding, and did not develop after deformation from a fine-grained aggregate by recrystallisation. Due to their monocrystallinity, their originally large size, and the solid inclusions forming the internal lamination, the Kristallbrocken have clearly stronger rheological properties than the surrounding fine- to coarse-grained polycrystalline rock salt, and thus also deform by fracturing.
    Keywords: Halite; Zechstein salt; Kristallbrocken; X-ray texture goniometry; Deformation mechanism; Crystallography ; 551 ; Earth Sciences; Geology ; Geophysics/Geodesy
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    Development of a 3D groundwater model based on scarce data: the Wadi Kafrein catchment/Jordan (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Keywords: Wadi Kafrein; Groundwater modelling; Model calibration; Arid and semiarid areas ; 551 ; Earth Sciences; Geology
    Language: English
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    Vertebrate tracksites in the Obernkirchen Sandstone (late Berriasian, Early Cretaceous) of northwest Germany— their stratigraphical, palaeogeographical, palaeoecological, and historical context (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-04-24
    Description: The northern German Lower Cretaceous Bückeberg Formation yields numerous dinosaur tracksites, some of which have produced material of impressive quality. Stratigraphically, the localities are concentrated in the Obernkirchen Sandstone, a thin subunit within this formation. The Obernkirchen Sandstone represents mainly a sandy barrier to back-barrier and lagoonal setting within a limnic deltaic facies complex, which was deposited during the late Berriasian (Cypridea alta formosa ostracod subzone) in the southeast of the Lower Saxony Basin, northwest Germany. A few tracksites occur more proximally in coeval fluvial deposits. Dinosaur footprint assemblages were left by ornithopods, theropods, sauropods, ankylosaurs, and small, bipedal ornithischians. Other vertebrate tracks are those of turtles and, possibly, crocodilians. Due to the decrease in sandstone quarrying in recent decades, many old tracksites are inaccessible today. Additionally, historical descriptions of the tracks were of highly variable quality and often published in remote and today nearly unobtainable sources. Here we provide a catalogue of 13 tracksites compiled from the literature and some new observations. Of these 13 tracksites, only five are still accessible and currently under study. Descriptions of each locality are provided, with a comprehensive compilation of existing data on lithofacies, stratigraphy, palaeogeography and palaeoecology of the Obernkirchen Sandstone and equivalent strata. A short review of the track-bearing lithofacies assemblage indicates that the outcrop areas have distinctly different facies and environments, and, therefore, track-bearing horizons can only be correlated stratigraphically between adjacent outcrops. For this reason, the identification of a megatracksite in the Obernkirchen Sandstone is currently regarded as premature and uncertain.
    Keywords: Vertebrate tracks; Dinosauria; Cretaceous; Berriasian; Obernkirchen; Münchehagen; Germany; Wirbeltier-Fährten; Dinosauria; Kreide; Berriasium; Obernkirchen; Münchehagen; Deutschland ; 551 ; Earth Sciences; Paleontology
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    The bipolar bivalve Oxytoma (Palmoxytoma) cygnipes (Young & Bird, 1822) in the Upper Pliensbachian of Germany (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-04-25
    Description: The morphologically conspicuous bivalve Oxytoma (Palmoxytoma) cygnipes (Young & Bird, 1822), known for its palaeogeographically bipolar distribution, from a limestone bed in the boundary “Belemniten–Schichten”/Amaltheenton formation, Lower Jurassic, in N Germany is described. The occurrence of this palaeoceanographically significant bivalve points to an influx of cool seawater from the Arctic to the North-German Basin at the base of the Upper Pliensbachian, just before the deposition of the Amaltheenton formation. A review of previously reported occurrences on the NW European Shelf indicates two distinct stratigraphic intervals of occurrence of this taxon: the Rhaetian–Hettangian boundary and the Upper Pliensbachian. Whereas the former interval of occurrence may be related to short-term cooling in the course of the end-Triassic extinction event, the latter is interpreted as reflecting the influx of a cool water current to the eastern part of the NW European Shelf, which continued southwards parallel to the coast of the Bohemian–Vindelician High.
    Keywords: Bivalvia; Germany; Triassic–Jurassic boundary; Pliensbachian; Boreal; Bivalvia; Deutschland; Trias–Jura-Grenze; Pliensbachium; Boreal ; 551 ; Earth Sciences; Paleontology
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    Ascomycete fungi on dimension stone of the “Burg Gleichen”, Thuringia (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: In the present study, the diversity of ascomycete fungi was investigated on two wall areas of the “Burg Gleichen”, Thuringia (Germany), made of various types of sandstones, travertine and Grenzdolomit. From a W-exposed, shaded wall area, free-living ascomycetes (mainly “black fungi”) and green algae could be retrieved from sandstone lithologies. Sandstone from an ESE-exposed area was mainly colonized by lichen ascomycetes and the lichen alga Trebouxia. Both areas share a small number of generalist species, related to the ascomycete black fungi Sarcinomyces petricola, Phaeococcomyces chersonesos and Stichococcus mirabilis. Free-living black fungi were isolated and characterized with respect to cell wall morphology and melanin content. A remarkably rigid melanin layer, incorporated in the cell wall of a Cladosporium isolate is presented in detail.
    Keywords: Dimension stone; Biofilm; Ascomycete fungi; Green algae; Cell wall; Melanin ; 551 ; Earth Sciences; Geology
    Language: English
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    Influence of shape fabric and crystal texture on marble degradation phenomena: simulations (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: Microstructure-based finite element simulations were used to study the influence of grain shape fabric and crystal texture on thermoelastic responses related to marble degradation phenomena. Calcite was used as an illustrative example for studying extremes of shape preferred orientation (SPO) in shape fabric and lattice preferred orientation (LPO) in crystal texture. Three SPOs were analyzed: equiaxed grains, elongated grains, and a mixture of equiaxed and elongated grains. Three LPOs were considered: a random orientation distribution function and two degrees of strong directional crystal texture. Finally, the correlation between the direction of the LPO with respect to that of the SPO was examined. Results show that certain combinations of SPO, LPO, and their directional relationship have significant influence on the thermomechanical behavior of marble. For instance, while there is no major dependence of the elastic strain energy density and the maximum principal stress on SPO for randomly textured microstructures, there is a strong synergy between LPO and its directional relationship with respect to the SPO direction. Microcracking precursors, elastic strain energy density, and maximum principal stress, decrease when the crystalline c-axes have fiber texture perpendicular to the SPO direction, but increase significantly when the c-axes have fiber texture parallel to the SPO direction. Moreover, the microstructural variability increases dramatically for these latter configurations. In general, the influence of LPO was as expected, namely, the strain energy density and the maximum principal stress decreased with more crystal texture, apart from for the exception noted above. Spatial variations of these precursors indicated regions in the microstructure with a propensity for microcracking. Unexpectedly, important variables were the microstructural standard deviations of the spatial distributions of the microcracking indicators. These microstructural standard deviations were as large as or larger than the variables themselves. The elastic misfit-strain contributions to the coefficients of thermal expansion were also calculated, but their dependence was as expected.
    Keywords: Shape fabric; Shape preferred orientation; Crystal texture; Lattice preferred orientation; Marble; Calcite; Finite element simulations; Thermal expansion anisotropy; Elastic strain energy density; Maximum principal stress; Orientation distribution function; Coefficient of thermal expansion ; 551 ; Earth Sciences; Geology
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    Development and assessment of protective winter covers for marble statuaries of the Schlossbrücke, Berlin (Germany) (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: The present study documents the results of an inter-disciplinary model project that was planned with the aim of developing an innovative winter covering system for marble statuaries located on the Schlossbrücke (Berlin). Such a system would need to fulfil the various requirements for structural stability, aesthetics, climate and practical use. This applied research represents the first complex scientific study of the sustainability of a winter covering system. The study is characterised by the use of complex scientific instruments such as special laboratory analysis and numerical simulation tools. The interaction between the environment and the artefacts in connection with the innovative winter covering structures were studied by extensive climatic monitoring.
    Keywords: Marble sculptures; Marble weathering; Winter cover; Climate data; Numerical simulations ; 551 ; Earth Sciences; Geology
    Language: English
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    The effect of air pollution on stone decay: the decay of the Drachenfels trachyte in industrial, urban, and rural environments—a case study of the Cologne, Altenberg and Xanten cathedrals (2018)
    Springer-Verlag | Berlin/Heidelberg
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    Publication Date: 2021-03-29
    Description: Severe stone deterioration is evident at the Cologne cathedral. In particular, the “Drachenfels” trachyte, which was the building material of the medieval construction period, shows significant structural deterioration as well as massive formation of gypsum crusts. The present article investigates crust formation on limestone, sandstone, and volcanic rock from the Cologne cathedral as well as from the Xanten and Altenberg cathedrals. These three buildings, showing varying degrees of deterioration, are located in different areas and exposed to varying industrial, urban, and rural pollution. Thin laminar and black framboidal crusts form on calcareous as well as silicate stone. The lack of a significant intrinsic calcium and sulfur source for the formation of the gypsum crusts on the Drachenfels trachyte indicates major extrinsic environmental impact: a sufficient offer of SOx from pollutant fluxes as well as external calcium sources (e.g., pollution, mortars, neighboring calcite stones). Chemical analyses reveal strong gypsum enrichment within the crusts as well as higher concentrations of lead and other pollutants (arsenic, antimony, bismuth, tin, etc.), which generally can be linked to traffic and industry. The formation of weathering crusts in an industrial environment is clearly distinguishable from that in rural areas. Scanning electron microscopy observations confirm that the total amount of pollution is less at the Altenberg cathedral than at the Cologne and Xanten cathedrals. XRF analyses show that the formation of gypsum occurs in lower amounts at Altenberg. This correlates well with the measured SO2 content and the intensity of the decay at the different locations. Furthermore, the different types of crusts, e.g., framboidal and laminar, can be differentiated and assigned to the different locations. The black weathering crusts on the silicate Drachenfels trachyte contribute to the degradation of the historic building material. They enhance mechanical moisture-related deterioration processes and the decay by chemical corrosion of rock-forming minerals. Although SO2 concentrations in air have shown a strong decrease over the past 30 years, degradation in connection with weathering crusts is still observed. This indicates that not only contemporary or recent emissions, but also past pollutant concentrations have to be considered.
    Keywords: Cologne cathedral; Xanten cathedral; Altenberg cathedral; Weathering crusts; Pollution impact; Stone decay processes; Drachenfels trachyte ; 551 ; Earth Sciences; Geology
    Language: English
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    Infiltration and groundwater flow into a fractured porous sandstone aquifer in the eastern Thuringian Basin (2018)
    Springer-Verlag | Springer-Verlag
    Details
    Publication Date: 2021-03-29
    Description: Kurzfassung Im Osten des Thüringer Beckens sind aufgrund der geringen Niederschläge von 585 mm/a die Grundwasserressourcen in den geklüfteten Buntsandsteingrundwasserleitern stark limitiert. Ziel der Untersuchung war es, für dieses Buntsandsteinfließsystem ein numerisches Grundwasserströmungsmodell zu erstellen, um die zukünftige Entwicklung der Grundwasserressourcen auf der Grundlage verschiedener Klimaszenarien prognostizieren zu können. Im vorliegenden Beitrag wurden Grundwasserganglinien mit dem Ziel analysiert, eine Inputfunktion für die Grundwasserneubildung am Grundwasserspiegel abzuleiten, welche ein wichtiger Eingangsparameter bei der numerischen Modellierung ist. Es konnte gezeigt werden, dass die Strömung im Buntsandsteingrundwasserleiter sowohl durch ein kluft- sowie ein matrixdominiertes Strömungsregime charakterisiert ist. Der überwiegende Anteil der Grundwasserneubildung infiltriert rasch durch das Kluftsystem. Dagegen bewirken die geringeren Matrixdurchlässigkeiten in der ungesättigten Zone, in Abhängigkeit vom Flurabstand, eine deutliche Verzögerung der Grundwasserneubildung von bis zu mehreren Jahren.
    Description: In the eastern Thuringian Basin, the low precipitation rate of 585 mm/y limits the groundwater resources in the sandstone aquifer system. The aim of this study was to develop a groundwater flow model for the region in order to forecast the impacts of different climate scenarios on the groundwater balance. Since recharge is of high relevance for the numerical model, a time series of groundwater levels were investigated to obtain the recharge input function. In the sandstone aquifer it could be shown that groundwater flow is characterised by flow in the fracture network as well as in the matrix. The largest fraction of recharge reaches the water table very quickly via the fracture network. However, both the thickness of the unsaturated zone and the low hydraulic conductivity of the sandstone matrix control the time lag of groundwater recharge. The time lag of the slow component to reach the water table is in the order of several years.
    Keywords: groundwater level; fractured porous sandstone aquifer; water table fluctuation; groundwater recharge; geostatistical estimation ; 551 ; Earth Sciences; Geoecology/Natural Processes; Soil Science & Conservation ; Applied Earth Sciences; Waste Water Technology / Water Pollution Control / Water Management / Aquatic Pollution; Hydrogeology
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  • 67
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    International Year of the Planet Earth (IYPE) und unsere FH-DGG-Tagung in Göttingen, Mai 2008 (2018)
    Springer-Verlag | Springer-Verlag
    Details
    Publication Date: 2021-03-29
    Keywords: 551 ; Geosciences; Geoecology/Natural Processes; Soil Science & Conservation ; Applied Geosciences ; Waste Water Technology / Water Pollution Control / Water Management / Aquatic Pollution; Hydrogeology
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  • 68
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    Stability assessment of sandstones from the St. Servatius Church in Quedlinburg (UNESCO’s World Heritage Site, Germany) (2018)
    Springer-Verlag | Berlin/Heidelberg
    Details
    Publication Date: 2021-03-29
    Description: The St. Servatius Church in Quedlinburg (UNESCO’s World Heritage Site, Germany) is characterised by long-standing stability problems and structural damages, which have been known over the last several centuries. The monotonous Cretaceous sandstone with its poor lithification is considered to be the main factor. The sandstone is characterised by a high porosity of around 30 Vol.% (max. ca. 35 Vol.%) and a corresponding high w-value. The porosity and the degree of cementation are responsible for the very low compressive strength of around 8 MPa at maximum, whereas under moisture these values are significantly reduced up to 40%. The freeze–thaw tests indicate a very poor resistance to frost weathering, which may explain the near-surface softening of the sandstone. Direct shear experiments with an approximate 60° angle of friction on the sandstone clearly demonstrate the safety margins. Initial geotechnical modelling does not favour the hypothesis that a landslide of the hill parallel to the southward dipping bedding planes (i.e. shear failure along weak zones) can occur. A prominent clay layer (also with a southward dip) below the entire castle hill is monitored to determine the possible amount of movement with respect to the geological discontinuities (e.g. joints, fractures). At present, a combination of foundation problems are being considered for the stability situation at the church. These include construction deficiencies due to deformation or softening of the foundation of the forerunner churches and missing or faulty connections from building additions. Geological factors responsible for the stability problems include the softening of the sandstone by the influence of weathering and penetrating water as well as the presence of possible shear planes and joints.
    Keywords: Cretaceous sandstone; Lithology; Diagenetic processes; Weathering; Petrophysical properties; Stability assessment ; 551 ; Earth Sciences; Geology
    Language: English
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  • 69
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    Black dimensional stones: geology, technical properties and deposit characterization of the dolerites from Uruguay (2018)
    Springer-Verlag | Berlin/Heidelberg
    Details
    Publication Date: 2021-03-29
    Description: Dimensional stones with a black color occupy a prominent place on the international market. Uruguayan dolerite dikes of andesitic and andesitic–basaltic composition are mined for commercial blocks of black dimensional stones. A total of 16 dikes of both compositions were studied and samples collected for geochemical and petrographical analysis. Color measurements were performed on different black dimensional stones in order to compare them with the Uruguayan dolerites. Samples of the two commercial varieties (Absolute Black and Moderate Black) were obtained for petrophysical analysis (e.g. density, porosity, uniaxial compressive strength, tensile strength, etc.). Detailed structural analyses were performed in several quarries. Geochemistry and petrography determines the intensity of the black color. The Uruguayan dolerite Absolute Black is the darkest black dimensional stone analyzed in this study. The petrophysical properties of Uruguayan dolerites make them one of the highest quality black dimensional stones. Structural analyses show that five joint sets have been recognized: two sub-vertical joints, one horizontal and two diagonal. These joint sets are one of the most important factors that control the deposits, since they control the block size distribution and the amount of waste material.
    Keywords: Dolerites; Black dimensional stones; Petrophysical properties; Structural analysis; Block size distribution; Uruguay ; 551 ; Earth Sciences; Geology
    Language: English
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  • 70
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    Direct observation of microcrack development in marble caused by thermal weathering (2018)
    Springer-Verlag | Berlin/Heidelberg
    Details
    Publication Date: 2021-03-29
    Description: One of the properties that makes marble such an excellent construction and ornamental material is its low porosity. It is very difficult for water or decay agents to penetrate the internal structure of materials with no or few pores, so enhancing the durability of these materials. However, environmental temperature fluctuations bring about significant physical changes in marbles that result in an increase in porosity, due to the appearance of new microcracks and the expansion of existing ones. These cracks offer new paths into the marble which make it easier for solutions containing pollutants to penetrate the material. Thermal expansion tests were performed on three different types of marble known as White, Tranco, and Yellow Macael (Almeria, Spain), after which an increase in porosity (from 17 to 73% depending on marble type) was observed, mainly due to crack formation. The structural changes occurring during thermal expansion tests were more significant in the case of White Macael samples, a fact that is not only related to its mineralogical composition but also to the morphology of the grains, grain boundaries and crystal size. Our research suggests that thermally weathered White Macael marble could be more susceptible to decay by other contaminant agents than Tranco or Yellow Macael. The use of hot-stage environmental scanning electron microscopy is proposed as a valid tool for observing, both in situ and at high magnification, changes in the fracture system of building stones induced by thermal stress.
    Keywords: Marble; Microcracks; Thermal expansion anisotropy; Grain boundaries ; 551 ; Earth Sciences; Geology
    Language: English
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  • 71
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    Multi-accretional tectonics at the Rio de la Plata Craton margins: preface (2018)
    Springer-Verlag | Berlin/Heidelberg
    Details
    Publication Date: 2021-03-29
    Keywords: 551 ; Earth Sciences; Geophysics/Geodesy; Geology
    Language: English
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  • 72
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    Coseismic recrystallization during shallow earthquake slip (2015)
    Geological Society of America
    Details
    Publication Date: 2020-11-26
    Description: Solidified frictional melts, or pseudotachylytes, remain the only unambiguous indicator of seismic slip in the geological record. However, pseudotachylytes form at 〉5 km depth, and there are many rock types in which they do not form at all. We performed low- to high-velocity rock friction experiments designed to impose realistic coseismic slip pulses on calcite fault gouges, and report that localized dynamic recrystallization may be an easy-to-recognize microstructural indicator of seismic slip in shallow, otherwise brittle fault zones. Calcite gouges with starting grain size 〈250 μm were confined up to 26 MPa normal stress using a purpose-built sample holder. Slip velocities were between 0.01 and 3.4 m s−1, and total displacements between 1 and 4 m. At coseismic slip velocities ≥0.1 m s−1, the gouges were cut by reflective principal slip surfaces lined by polygonal grains 〈1 μm in size. The principal slip surfaces were flanked by 〈300 μm thick layers of dynamically recrystallized calcite (grain size 1–10 μm) containing well-defined shape- and crystallographic-preferred orientations. Dynamic recrystallization was accompanied by fault weakening and thermal decomposition of calcite to CO2 + CaO. The recrystallized calcite aggregates resemble those found along the principal slip surface of the Garam thrust, South Korea, exhumed from 〈5 km depth. We suggest that intense frictional heating along the experimental and natural principal slip surfaces resulted in localized dynamic recrystallization, a microstructure that may be diagnostic of seismic slip in the shallow crust.
    Description: Published
    Description: 63-66
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: JCR Journal
    Description: reserved
    Keywords: Rock mechanics ; shallow earthquales ; 04. Solid Earth::04.01. Earth Interior::04.01.04. Mineral physics and properties of rocks ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 73
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    Mirror-like faults and power dissipation during earthquakes (2015)
    Geological Society of America
    Details
    Publication Date: 2021-05-17
    Description: Earthquakes occur along faults in response to plate tectonic movements, but paradoxically, are not widely recognized in the geological record, severely limiting our knowledge of earthquake physics and hampering accurate assessments of seismic hazard. Light-reflective (so-called mirror like) fault surfaces are widely observed geological features, especially in carbonate-bearing rocks of the shallow crust. Here we report on the occurrence of mirror-like fault surfaces cutting dolostone gouges in the Italian Alps. Using friction experiments, we demonstrate that the mirror-like surfaces develop only at seismic slip rates (∼1 m/s) and for applied normal stresses and sliding displacements consistent with those estimated on the natural faults. Under these experimental conditions, the frictional power density dissipated in the samples is comparable to that estimated for natural earthquakes (1–10 MW/m2). Our results indicate that mirror-like surfaces in dolostone gouges are a signature of seismic faulting, and can be used to estimate power dissipation during ancient earthquake ruptures.
    Description: Published
    Description: 1175-1178
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: JCR Journal
    Description: reserved
    Keywords: Earthquakes ; Faults ; Carbonates ; Rock Mechanics ; 04. Solid Earth::04.01. Earth Interior::04.01.04. Mineral physics and properties of rocks ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 74
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    Dynamic feeder dyke systems in basaltic volcanoes: the exceptional example o fthe 1809 Etna eruption (Italy) (2015)
    Nature Publishing Group
    Details
    Publication Date: 2017-04-04
    Description: In this paper, we describe the 1809 eruption of Mt. Etna, Italy, which represents one historical rare case in which it is possible to observe details of the internal structure of the feeder system. This is possible thanks to the presence of two large pit craters located in the middle of the eruptive fracture field that allow studying a section of the shallow feeder system. Along the walls of one of these craters, we analysed well-exposed cross sections of the uppermost 15–20 m of the feeder system and related volcanic products. Here, we describe the structure, morphology and lithology of this portion of the 1809 feeder system, including the host rock which conditioned the propagation of the dyke, and compare the results with other recent eruptions. Finally, we propose the dynamic model of the magma behaviour inside a laterally-propagating feeder dyke, demonstrating how this dynamic triggered important changes in the eruptive style (from effusive/Strombolian to phreatomagmatic) during the same eruption. Our results are also useful for hazard assessment related to the development of flank eruptions, potentially the most hazardous type of eruption from basaltic volcanoes in densely urbanized areas, such as Mt. Etna.
    Description: Published
    Description: 1-11
    Description: 2T. Tettonica attiva
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 3V. Dinamiche e scenari eruttivi
    Description: 4V. Vulcani e ambiente
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: N/A or not JCR
    Description: open
    Keywords: feeder dyke ; basaltic volcanoes ; flank eruptions ; Etna ; volcanic hazards ; sill ; volcanic rift ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 75
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    Introduction: The ANDRILL McMurdo Ice Shelf (MIS) and Southern McMurdo Sound (SMS) Drilling Projects (2012)
    Geological Society of America
    Details
    Publication Date: 2017-04-04
    Description: No Abstract
    Description: Published
    Description: 546-547
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: restricted
    Keywords: Stratigraphic Drilling ; McMurdo Ice Shelf ; Chronostratigraphy ; Neogene ; Tectonics ; Ice Sheet history ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy
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  • 76
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    Neogene deformation and granite emplacement in the metamorphic units of northern Apennines (Italy): Insights from mylonitic marbles in the Porto Azzurro pluton contact aureole (Elba Island) (2012)
    Geological Society of America
    Details
    Publication Date: 2017-04-04
    Description: In the northern Tyrrhenian Sea, late Miocene intrusions (Monte Capanne pluton and Porto Azzurro pluton) were emplaced at upper crustal levels (〈0.2 GPa) in the thrust systems of Elba Island. The emplacement of intrusive rocks is currently explained in the context of late Miocene extensional tectonics. New detailed structural data collected along a continuous natural cross section through the contact aureole of the Porto Azzurro pluton (eastern Elba) where strain localization has occurred within two west-dipping decameter-scale carbonate shear zones, namely the Calanchiole and Felciaio shear zones, are reported here. These shear zones, characterized by a lithological difference with calcite and dolomite marbles dominant in the Calanchiole and Felciaio shear zones, respectively, exhibit a similar rheological behavior. They represent two weakened layers in which west-dipping mylonitic foliation, sheath folds, boudinage structures, and upright folds developed within the contact aureole. Moreover, in correspondence with the Felciaio shear zone, the inversion of metamorphic facies occurs. Meso- and microstructural data give evidence that most of the deformation and displacement in the shear zones was coeval with contact metamorphism and developed under metamorphic conditions retrograde from pyroxene hornfels to hornblende-hornfels facies. Geometric and kinematic features indicate that both shear zones correspond to ductile thrusts, which led to internal stacking of the contact aureole. Therefore, at Elba Island, emplacement of intrusive rocks coeval with late Miocene crustal shortening gives a new perspective on relations between tectonics and magmatism in the northern Apennines.
    Description: Published
    Description: 470-490
    Description: 1.10. TTC - Telerilevamento
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: granite emplacement ; contact aureole ; deformation and metamorphism ; Neogene ; northern Apennines ; Elba Island ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 77
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    The 2009 paroxysmal explosions at Stromboli (Italy): magma mixing and eruption dynamics (2012)
    Springer-Verlag
    Details
    Publication Date: 2017-04-04
    Description: Three small-scale paroxysmal explosions (also called major explosions) interrupted ordinary mild Strombolian activity at Stromboli on May 3, November 8 and 24, 2009. Products were largely confined to the summit area, except in the November 24 event, during which coarse pumiceous lapilli reached the coast. Emission of crystal-poor pumice closely mingled with crystal-rich products characterized the three events. The textural and chemical study of minerals and glassy matrices revealed that the two end-members are mingled together physically in the May 3 and November 24 pumice, whereas November 8 products contain heterogeneous glass with intermediate compositions derived from chemical mixing between crystal-rich and crystal-poor magmas. We here discuss the different degrees of interaction between the two magmas in the three explosions in terms of magma dynamics during small-scale paroxysms.
    Description: Published
    Description: 1147-1154
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli ; Paroxysm ; Glass chemistry ; Mixing ; Eruption dynamics ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 78
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    A spatter-forming, large-scale paroxysm at Stromboli Volcano (Aeolian Islands, Italy): insight into magma evolution and eruption dynamics (2012)
    Springer-Verlag
    Details
    Publication Date: 2017-04-04
    Description: This study focuses on a pyroclastic sequence related to a large-scale paroxysm that occurred during the seventeenth century ad and which can be considered one of the most powerful and hazardous explosive events at the volcano in the past few centuries. Paroxysms are energetic, short-lived explosions which sporadically interrupt normal Strombolian activity at Stromboli and commonly erupt a deep-derived, volatile-rich crystal-poor high-potassium basalt (“low porphyricity” (LP)), together with a shallow, degassed crystal-rich high-potassium to shoshonitic basalt (“high porphyricity” (HP)), which feed normal activity at the volcano. The studied deposit, crops out along the flanks of Sciara del Fuoco and, from base to top, consists of: (1) a layer of HP and LP ash and lapilli; (2) an unwelded layer of coarse HP lapilli and flattened dark scoriae; (3) weakly welded spatter made up of dense HP pyroclasts at the base, overlain by strongly vesicular LP clasts. The textural and chemical zoning of minerals and the glass chemistry of the LP products record repeated mafic recharge events, mixing with an old mushy body and episodes of rapid crystallization due to sudden degassing. Collapse of a foam layer originated by deep degassing probably triggered this large-scale, spatter-forming paroxysm. Decompression induced rapid degassing and vesiculation of the deep volatile-rich magma. The rapid ascent of the foamy magma blob pushed the shallow HP magma out and finally produced a fire fountain that emplaced the LP portion of the spatter.
    Description: Published
    Description: 1393-1406
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: Explosive paroxysm ; Mineral zoning ; Magma evolution ; Eruption dynamics ; Stromboli ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 79
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    Paroxysmal activity at Stromboli: lessons from the past (2012)
    Springer-Verlag
    Details
    Publication Date: 2017-04-04
    Description: The persistent normal activity of Stromboli is occasionally interrupted by sudden and highly energetic explosive events called Strombolian paroxysms. These phenomena together with landslide-generated tsunamis represent the most hazardous manifestations of present-day volcanic activity at Stromboli. The most recent paroxysms, on 5 April 2003 and 15 March 2007, have drawn attention to these energetic events because they significantly threatened inhabitants and tourists. Historical accounts and field evidence indicate, however, that even larger paroxysms, in terms of volume, dispersal of products and intensity of explosive phenomena, occurred in the recent past. During these paroxysms incipiently welded spatter deposits mantled the north and south rims of the Sciara del Fuoco down to low elevations, extending much farther than the similar deposits from recent observed events (5 April 2003 and 15 March 2007). In order to identify, characterize and discriminate among products of these outstanding spatter-forming eruptions, more than 50 stratigraphic sections were measured and sampled. Stratigraphic, sedimentological and radiometric (14C) data indicate that only two paroxysms produced spatter that reached very low elevations and inhabited areas: the first occurred in the 16th century and the last in AD 1930. Analysis of texture and deposit components reveals that the early phases of the two eruptions were driven by distinctly different eruptive dynamics. Both identified paroxysms are at least one order of magnitude greater than any similar event observed by monitoring systems at Stromboli. These two large paroxysms were the most powerful volcanic events at Stromboli in the last eighteen centuries.
    Description: Published
    Description: 1229-1243
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli ; Paroxysms ; Spatter ; Basaltic explosive volcanism ; Volcanic hazard ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 80
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    Rapid differentiation in a sill-like magma reservoir: a case study from the campi flegrei caldera (2012)
    Nature Publishing Group
    Details
    Publication Date: 2017-04-04
    Description: In recent decades, geophysical investigations have detected wide magma reservoirs beneath quiescent calderas. However, the discovery of partially melted horizons inside the crust is not sufficient to put constraints on capability of reservoirs to supply cataclysmic eruptions, which strictly depends on the chemical-physical properties of magmas (composition, viscosity, gas content etc.), and thus on their differentiation histories. In this study, by using geochemical, isotopic and textural records of rocks erupted from the high-risk Campi Flegrei caldera, we show that the alkaline magmas have evolved toward a critical state of explosive behaviour over a time span shorter than the repose time of most volcanic systems and that these magmas have risen rapidly toward the surface. Moreover, similar results on the depth and timescale of magma storage were previously obtained for the neighbouring Somma-Vesuvius volcano. This consistency suggests that there might be a unique long-lived magma pool beneath the whole Neapolitan area.
    Description: Published
    Description: article 712
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: N/A or not JCR
    Description: open
    Keywords: magma ; campi flegrei caldera ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 81
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    Orbitally forced paleoenvironmental and paleoclimate changes in the late postevaporitic Messinian of the central Mediterranean Basin (2012)
    Geological Society of America
    Details
    Publication Date: 2022-06-14
    Description: Paleoenvironmental and paleoclimate changes that occurred during the late postevaporitic stage of the Mediterranean Basin in the Messinian foreland domain of the Adriatic region offer a new perspective on the relationship between orbital forcing and climate response. The magnetic susceptibility record of the Fonte dei Pulcini A section (Maiella Mountains, Italy) allows us to orbitally tune the record between 5.394 and 5.336 Ma and to temporally constrain the paleoenvironmental and paleoclimate changes evidenced by quantitative paleontological (palynomorphs, ostracods, and calcareous nannofossils), stable isotope (δ18O and δ13C), and X-ray diffraction (XRD) analyses. The base of the Fonte dei Pulcini A section is characterized by Paratethyan ostracods and dinocysts, which point to the late Messinian Lago-Mare biofacies (Loxocorniculina djafarovi zone) of the Mediterranean Messinian stratigraphy. From paleontological and geochemical (δ18O) analyses, there is no evidence of a marine incursion in the Fonte dei Pulcini A section. The major changes in terms of paleodepth, paleosalinity, evaporation versus precipitation, aridity versus humidity, and reworking processes occurred in the upper part of the Fonte dei Pulcini A section, during the last Messinian insolation cycle (i-cycle 511/512), which is characterized by high-amplitude oscillations. In contrast, the lower part of the Fonte dei Pulcini A section, which was deposited during relatively low-amplitude insolation cycles, is characterized by more stable environmental conditions. Comparing summer insolation with the paleoenvironmental changes at the Fonte dei Pulcini A section, we identify delays of several thousands of years between orbital forcing and climate response.
    Description: Published
    Description: 499-516
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: Messinian stage ; Lago-Mare event ; Maiella ; Apennines ; 03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.09. Environmental magnetism
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  • 82
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    Early and middle Miocene Antarctic glacial history from the sedimentary facies distribution in the AND-2A drill hole, Ross Sea, Antarctica (2012)
    Geological Society of America
    Details
    Publication Date: 2022-06-14
    Description: In 2007, the Antarctic Geological Drilling Program (ANDRILL) drilled 1138.54 m of strata ~10 km off the East Antarctic coast, includ ing an expanded early to middle Miocene succession not previously recovered from the Antarctic continental shelf. Here, we pre sent a facies model, distribution, and paleoclimatic interpretation for the AND-2A drill hole, which enable us, for the fi rst time, to reconstruct periods of early and middle Miocene glacial advance and retreat and paleo environmental changes at an ice-proximal site. Three types of facies associations can be recognized that imply signifi cantly different paleoclimatic interpretations. (1) A diamictite-dominated facies association represents glacially dominated depositional environments, including subglacial environments, with only brief intervals where ice-free coasts existed, and periods when the ice sheet was periodically larger than the modern ice sheet. (2) A stratified diamictite and mudstone facies association includes facies characteristic of open-marine to iceberg-infl uenced depositional environments and is more consistent with a very dynamic ice sheet, with a grounding line south of the modern position. (3) A mudstone-dominated facies association generally lacks diamictites and was produced in a glacially infl uenced hemipelagic depositional environment. Based on the distribution of these facies associations, we can conclude that the Antarctic ice sheets were dynamic, with grounding lines south of the modern location at ca. 20.1–19.6 Ma and ca. 19.3–18.7 Ma and during the Miocene climatic optimum, ca. 17.6–15.4 Ma, with ice-sheet and sea-ice minima at ca. 16.5–16.3 Ma and ca. 15.7–15.6 Ma. While glacial minima at ca. 20.1–19.6 Ma and ca. 19.3–18.7 Ma were characterized by temperate margins, an increased abundance of gravelly facies and diatomaceous siltstone and a lack of meltwater plume deposits suggest a cooler and drier climate with polythermal conditions for the Miocene climatic optimum (ca. 17.6–15.4 Ma). Several periods of major ice growth with a grounding line traversing the drill site are recognized between ca. 20.2 and 17.6 Ma, and after ca. 15.4 Ma, with evidence of cold polar glaciers with ice shelves. The AND-2A core provides proximal evidence that during the middle Miocene climate transition, an ice sheet larger than the modern ice sheet was already present by ca. 14.7 Ma, ~1 m.y. earlier than generally inferred from deep-sea oxygen isotope records. These fi ndings highlight the importance of high-latitude ice-proximal records for the interpretation of far-fi eld proxies across major climate transitions.
    Description: Published
    Description: 2352-2365
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: ANDRILL-SMS ; Miocene ; Ross Sea ; Antarctica ; 03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
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  • 83
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    Slope instability induced by volcano-tectonics as an additional source of hazard in active volcanic areas: the case of Ischia island (Italy) (2011)
    Springer-Verlag
    Details
    Publication Date: 2017-04-04
    Description: Ischia is an active volcanic island in the Gulf of Naples whose history has been dominated by a calderaforming eruption (ca. 55 ka) and resurgence phenomena that have affected the caldera floor and generated a net uplift of about 900 m since 33 ka. The results of new geomorphological, stratigraphical and textural investigations of the products of gravitational movements triggered by volcano-tectonic events have been combined with the information arising from a reinterpretation of historical chronicles on natural phenomena such as earthquakes, ground deformation, gravitational movements and volcanic eruptions. The combined interpretation of all these data shows that gravitational movements, coeval to volcanic activity and uplift events related to the long-lasting resurgence, have affected the highly fractured marginal portions of the most uplifted Mt. Epomeo blocks. Such movements, mostly occurring since 3 ka, include debris avalanches; large debris flows (lahars); smaller mass movements (rock falls, slumps, debris and rock slides, and small debris flows); and deep-seated gravitational slope deformation. The occurrence of submarine deposits linked with subaerial deposits of the most voluminous mass movements clearly shows that the debris avalanches impacted on the sea. The obtained results corroborate the hypothesis that the behaviour of the Ischia volcano is based on an intimate interplay among magmatism, resurgence dynamics, fault generation, seismicity, slope oversteepening and instability, and eruptions. They also highlight that volcano-tectonically triggered mass movements are a potentially hazardous phenomena that have to be taken into account in any attempt to assess volcanic and related hazards at Ischia. Furthermore, the largest mass movements could also flow into the sea, generating tsunami waves that could impact on the island’s coast as well as on the neighbouring and densely inhabited coast of the Neapolitan area.
    Description: Published
    Description: 79-106
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: Ischia . ; Caldera resurgence ; Slope instability ; Debris avalanche ; Lahar ; Volcanic and related hazards ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 84
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    The Monte Orfano Conglomerate revisited: stratigraphic constraints on Cenozoic tectonic uplift of the Southern Alps (Lombardy, northern Italy) (2011)
    Springer-Verlag
    Details
    Publication Date: 2017-04-04
    Description: The Monte Orfano Conglomerate (MOC), exposed in the foothills of the Southern Alps (northern Italy), is one of the few outcrops of sediments documenting the Cenozoic tectonic evolution of the Alpine retrowedge. Calcareous nannofossil biostratigraphy allowed us to constrain the upper part of the MOC, formerly attributed to the Early-Middle Miocene in the type-locality, to the earliest Miocene (Neogene part of the NN1 nannofossil zone). A likely latest Oligocene age is therefore suggested for the bulk of the underlying conglomerates, whose base is not exposed. Deposition of the MOC can be placed within the post-collisional tectonic uplift of the Alps, documented in the Lake Como area by the Como Conglomerate (CC) at the base of the Gonfolite Lombarda Group, and supports the correlation with Upper Oligocene clastic sediments cropping out further to the East, in the Lake Garda and in the Veneto-Friuli areas (‘‘molassa’’). The remarkable difference in petrographic composition between the western (CC) and eastern (MOC) clastics deposited in the Alpine retro-foreland basin highlights the synchronous tectonic activity of two structural domains involving different crustal levels. Whilst the bulk of the CC, that straddles the Oligocene/Miocene boundary, records largely the tectonic exhumation of the Alpine axial chain crystalline complexes, the coeval MOC consists of detritus derived from the superficial crustal section (Triassic to Paleogene sedimentary rocks) of the Alpine retrowedge and constrains the onset of the post-collisional deformation phase of the Southern Alps as not younger than the Late Oligocene.
    Description: Published
    Description: 1335-1355
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: Southern Alps ; Cenozoic ; Calcareous Nannofossil biostratigraphy ; Clastic Provenance ; Shelf Fan-Delta ; Retroforeland basin ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 85
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    Monogenetic vent self-similar clustering in extending continental crust: Examples from the East African Rift System (2011)
    Geological Society of America
    Details
    Publication Date: 2017-04-04
    Description: The spatial clustering of fracture networks and vents in basaltic volcanic fields has been analyzed in three sectors of the East African Rift System, the classical example of an active continental rift. Fracture trace maps and monogenetic basaltic vents have been thus collected in the Afar Depression, in the Main Ethiopian Rift, and in the Virunga Belt (Western Rift). The mapped vents are generally younger than 2 Ma, and most are of Holocene age. All the analyzed fracture networks have self-similar clustering with fractal exponents (Df) varying in the 1.54−1.85 range. Also, vents show a self-similar clustering with fractal exponents (Dv) in the 1.17−1.50 range. For all the studied sectors, the relationship Df 〉 Dv has been observed. The fractal exponents for vents (Dv) of power-law distributions are computed in a range of lengths with a lower and an upper cutoff. The upper cutoff (Uco) for the fractal clustering of vents in the studied sectors of the East African Rift System are compared with the respective crust thickness derived by independent geophysical data. The computed Ucos for the studied sectors well match the crust thickness in the volcanic fields. A preliminary conceptual model to explain the relationships between the upper cutoffs of the fractal distribution of vents and the thickness of the crust in the volcanic fields is thus proposed in the light of the percolation theory.
    Description: Published
    Description: 1.10. TTC - Telerilevamento
    Description: 3.2. Tettonica attiva
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: crustal thickness ; basaltic volcanic fields ; vent distribution ; EASR ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 86
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    Introduction: LASI III—Magma pulses and sheets in tabular intrusions (2011)
    Geological Society of America
    Details
    Publication Date: 2017-04-04
    Description: The origins of granites and intrusive rocks have been widely discussed for a couple of centuries, and the way volcanoes work and their magma forms have attracted scientists, naturalists, and laymen since the dawn of humankind. However, shallow igneous intrusions, representing the obvious link between the hidden kingdom of Pluto and the fiery realm of Vulcanus, have been partly overlooked, leading to some lack of communication between “plutonic” and “volcanic” researchers. An effort devoted to heal this breach has been contributed to by the establishment of the LASI conferences (named after laccolith and sill, the main types of shallow igneous intrusions).
    Description: Published
    Description: 161-162
    Description: 3.2. Tettonica attiva
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: upper crustal level intrusions ; emplacement of magma ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
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  • 87
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    The Pomici di Avellino eruption of Somma–Vesuvius (3.9 ka BP). Part II: sedimentology and physical volcanology of pyroclastic density current deposits (2011)
    Springer-Verlag
    Details
    Publication Date: 2021-12-16
    Description: Pyroclastic density currents (PDCs) generated during the Plinian eruption of the Pomici di Avellino (PdA) of Somma–Vesuvius were investigated through field and laboratory studies, which allowed the detailed reconstruction of their eruptive and transportation dynamics and the calculation of key physical parameters of the currents. PDCs were generated during all the three phases that characterised the eruption, with eruptive dynamics driven by both magmatic and phreatomagmatic fragmentation. Flows generated during phases 1 and 2 (EU1 and EU3pf, magmatic fragmentation) have small dispersal areas and affected only part of the volcano slopes. Lithofacies analysis demonstrates that the flow-boundary zones were dominated by granular-flow regimes, which sometimes show transitions to traction regimes. PDCs generated during eruptive phase 3 (EU5, phreatomagmatic fragmentation) were the most voluminous and widespread in the whole of Somma–Vesuvius’ eruptive history, and affected a wide area around the volcano with deposit thicknesses of a few centimetres up to more than 25 km from source. Lithofacies analysis shows that the flowboundary zones of EU5 PDCs were dominated by granular flows and traction regimes. Deposits of EU5 PDC show strong lithofacies variation northwards, from proximally thick, massive to stratified beds towards dominantly alternating beds of coarse and fine ash in distal reaches. The EU5 lithofacies also show strong lateral variability in proximal areas, passing fromthe western and northern to the eastern and southern volcano slopes, where the deposits are stacked beds of massive, accretionary lapilli-bearing fine ash. The sedimentological model developed for the PDCs of the PdA eruption explains these strong lithofacies variations in the light of the volcano’s morphology at the time of the eruption. In particular, the EU5 PDCs survived to pass over the break in slope between the volcano sides and the surrounding volcaniclastic apron–alluvial plain, with development of new flows from the previously suspended load. Pulses were developed within individual currents, leading to stepwise deposition on both the volcano slopes and the surrounding volcaniclastic apron and alluvial plain. Physical parameters including velocity, density and concentration profile with height were calculated for a flow of the phreatomagmatic phase of the eruption by applying a sedimentological method, and the values of the dynamic pressure were derived. Some hazard considerations are summarised on the assumption that, although not very probable, similar PDCs could develop during future eruptions of Somma–Vesuvius
    Description: Published
    Description: 559–577
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Pyroclastic density currents ; Pomici diAvellino ; Somma–Vesuvius ; Dynamic pressure ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 88
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    The Pomici di Avellino eruption of Somma-Vesuvius (3.9 ka BP). Part I: stratigraphy, compositional variability and eruptive dynamics (2011)
    Springer-Verlag
    Details
    Publication Date: 2021-12-16
    Description: The stratigraphic succession of the Pomici di Avellino Plinian eruption from Somma-Vesuvius has been studied through field and laboratory data in order to reconstruct the eruption dynamics. This eruption is particularly important in the Somma-Vesuvius eruptive history because (1) its vent was offset with respect to the present day Vesuvius cone; (2) it was characterised by a distinct opening phase; (3) breccia-like very proximal fall deposits are preserved close to the vent and (4) the pyroclastic density currents generated during the final phreatomagmatic phase are among the most widespread and voluminous in the entire history of the volcano. The stratigraphic succession is, here, divided into deposits of three main eruptive phases (opening, magmatic Plinian and phreatomagmatic), which contain five eruption units. Short-lived sustained columns occurred twice during the opening phase (Ht of 13 and 21.5 km, respectively) and dispersed thin fall deposits and small pyroclastic density currents onto the volcano slopes. The magmatic Plinian phase produced the main volume of erupted deposits, emplacing white and grey fall deposits which were dispersed to the northeast. Peak column heights reached 23 and 31 km during the withdrawal of the white and the grey magmas, respectively. Only one small pyroclastic density current was emplaced during the main Plinian phase. In contrast, the final phreatomagmatic phase was characterised by extensive generation of pyroclastic density currents, with fallout deposits very subordinate and limited to the volcano slopes. Assessed bulk erupted volumes are 21×106 m3 for the opening phase, 1.3– 1.5 km3 for the main Plinian phase and about 1 km3 for the final phreatomagmatic phase, yielding a total volume of about 2.5 km3. Pumice fragments are porphyritic with sanidine and clinopyroxene as the main mineral phases but also contain peculiar mineral phases like scapolite, nepheline and garnet. Bulk composition varies from phonolite (white magma) to tephri-phonolite (grey magma).
    Description: Published
    Description: 539–558
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Avellino eruption ; Somma-Vesuvius ; Stratigraphy ; Eruptive dynamics ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 89
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    Late Miocene Submarine Volcanism in the Ross Embayment, Antarctica (2010)
    Geological Society of America
    Details
    Publication Date: 2017-04-04
    Description: Abstract: The ANDRILL McMurdo Ice Shelf (MIS) initiative recovered a 1285 m-long core (MIS AND-1B) composed of cyclic glacimarine sediments with interbedded volcanic deposits. By far the thickest continuous volcanic sequence is about 175 m long and is found at midcore depths from 584.19 to 759.32 meters below sea floor (mbsf). The sequence was logged and initial interpretations of lithostratigraphic subdivisions were made on-ice during drilling in late 2006. Subsequent observations, based on image, petrographic, and SEM-EDS analyses, provide a more detailed, revised interpretation of a thick submarine to emergent volcanic succession. The sequence is subdivided into two main subsequences on the basis of sediment composition, texture and alteration style. The ~70 m thick lower subsequence consists mostly of monothematic stacked volcanic-rich mudstone and sandstone deposits, which are attributed to epiclastic gravity flow turbidite processes. This subsequence is consistent with abundant active volcanism that occurred at a distal site with respect to the drill site. The ~105 m thick upper subsequence consists mainly of interbedded tuff, lapilli tuff, and volcanic diamictite. A late Miocene (6.48 Ma) 2.81 m-thick subaqueously emplaced lava flow occurs within the second subsequence. This second subsequence is attributed to recurring cycles of submarine to emergent volcanic activity that occurred proximal to the drill site. This new dataset provides 1) the first rock evidence of significant late Miocene submarine volcanic activity in the Ross Embayment during a period of no to limited glaciation , and 2) a rich stratigraphic record that elucidates submarine volcano-sedimentary processes in an off-shore setting.
    Description: In press
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: open
    Keywords: ANDRILL ; AND1-B core ; McMurdo Sound ; submarine volcanism ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 90
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    Cryogenic origin for brine in the subsurface of southern McMurdo Sound, Antarctica (2010)
    Geological Society of America
    Details
    Publication Date: 2020-02-24
    Description: Sampling of interstitial fluids during deep coring in southern McMurdo Sound, Antarctica, revealed the presence of seawater-sourced, hypersaline brine at depths 〉200 m below the sea-floor. Na-Cl-Br and SO4-Cl-Br relationships are consistent with a concentration mechanism that involves the removal of pure H2O as ice and precipitation of mirabilite (Na2SO4·10H2O) during progressive freezing of seawater. The brine is in Neogene subglacial, glacimarine, and marine facies that record advance and retreat of glaciers through the Ross Sea embayment. In this environment, sea ice formation in semi-isolated marine basins that occupied flexural troughs along ice sheet margins produced dense brines that sank and infiltrated the permeable subglacial sediment. Repeated cycles of glacial advance and retreat provided multiple opportunities for batches of seawater to be transformed into brine that now is in the subsurface of southern McMurdo Sound. Results demonstrate the feasibility of brine formation via seawater freezing and attest to the potential of a cryogenic origin for subsurface brines in high-latitude regions of the Northern Hemisphere, as proposed by some workers.
    Description: Published
    Description: 587-590
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: restricted
    Keywords: ANDRILL ; SMS Project ; interstitial fluids ; hypersaline brine ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy
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  • 91
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    40 Ar/ 39 Ar radiometric dating to constrain the volcanic stratigraphy: The Mt. Etna methodological case. (2010)
    Geological Society of America
    Details
    Publication Date: 2017-04-04
    Description: Although ~50 radiometric age analyses have been performed on Etna, and there are many historical references, these are not enough to temporally constrain the geo- logical evolution of the volcano. In particular, a new stratigraphic framework based on lithostratigraphic and unconformity-bounded units has pointed out the presence of some stratigraphic uncertainty that can be resolved only with radiometric dating. For this reason, a dating project applying the 40 Ar/ 39 Ar incremental heating technique started in 2002. The results obtained improve our understanding and provide con- straints for Etna’s geological evolution; in addition, they show that the applied tech- nique is very useful for dating young basalts and quantifying the hiatus represented by unconformities, as well as for understanding their meaning.
    Description: Published
    Description: 241-248
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: restricted
    Keywords: Ar/Ar dating ; Etna ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 92
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    Revised slip rates for the Alpine fault at Inchbonnie: Implications for plate boundary kinematics of South Island, New Zealand (2010)
    Geological Society of America
    Details
    Publication Date: 2017-04-04
    Description: The northeast-striking, dextral-reverse Alpine fault transitions into the Marlborough Fault System near Inchbonnie in the central South Island, New Zealand. New slip-rate estimates for the Alpine fault are presented following a reassessment of the geomorphology and age of displaced late Holocene alluvial surfaces of the Taramakau River at Inchbonnie. Progressive avulsion and abandonment of the Taramakau floodplain, aided by fault movements during the late Holocene, have preserved a left-stepping fault scarp that grows in height to the northeast. Surveyed dextral (22.5 ± 2 m) and vertical (4.8 ± 0.5 m) displacements across a left stepover in the fault across an alluvial surface are combined with a precise maximum age from a remnant tree stump (≥1590–1730 yr) to yield dextral, vertical, and reverse-slip rates of 13.6 ± 1.8, 2.9 ± 0.4, and 3.4 ± 0.6 mm/yr, respectively. These values are larger (dextral) and smaller (dip slip) than previous estimates for this site, but they refl ect advances in the local chronology of surfaces and represent improved time-averaged results over 1.7 k.y. A geological kinematic circuit constructed for the central South Island demonstrates that (1) 69%–89% of the Australian-Pacific plate motion is accommodated by the major faults (Alpine-Hope-Kakapo) in this transitional area, (2) the 50% drop in slip rate on the Alpine fault between Hokitika and Inchbonnie is taken up by the Hope and Kakapo faults at the southwestern edge of the Marlborough Fault System, and (3) the new slip rates are more compatible with contemporary models of strain partitioning presented from geodesy.
    Description: Published
    Description: 139-152
    Description: 3.2. Tettonica attiva
    Description: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale
    Description: N/A or not JCR
    Description: reserved
    Keywords: Alpine fault ; plate boundary ; slip rate ; New Zealand ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.02. Geochronology ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 93
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    Possible causes of arc development in the Apennines, central Italy (2010)
    Geological Society of America
    Details
    Publication Date: 2022-06-14
    Description: In central Italy, the geometry, kinematics, and tectonic evolution of the late Neogene Umbrian Arc, which is one of the main thrusts of the northern Apennines, have long been studied. Documented evidence for orogenic curvature includes vertical axis rotations along both limbs of the arc and a positive orocline test along the entire arc. The cause of the curvature is, however, still unexplained. In this work, we focus our attention on the southern portion of the Umbrian Arc, the so-called Olevano- Antrodoco thrust. We analyze, in particular, gravity and seismic-reflection data and consider available paleomagnetic, stratigraphic, structural, and topographic evidence from the central Apennines to infer spatial extent, attitude, and surface effects of a midcrustal anticlinorium imaged in the CROP-11 deep seismic profile. The anticlinorium has horizontal dimensions of ~50 by 30 km, and it is located right beneath the Olevano- Antrodoco thrust. Stratigraphic, structural, and topographic evidence suggests that the anticlinorium produced a surface uplift during its growth in early Pliocene times. We propose an evolutionary model in which, during late Neogene time, the Olevano- Antrodoco thrust developed in an out-of sequence fashion and underwent ~16° of clockwise rotation when the thrust ran into and was then raised and folded by the growing anticlinorium (late Messinian–early Pliocene time). This new model suggests a causal link between midcrustal folding and surficial orogenic curvature that is consistent with several available data sets from the northern and central Apennines; more evidence is, however, needed to fully test our hypothesis. Additionally, due to the occurrence of midcrustal basement-involved thrusts in other orogens, this model may be a viable mechanism for arc formation elsewhere.
    Description: Published
    Description: 1409-1420
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: oroclines ; Apennines ; fold and thrust belts ; gravity anomalies ; seismic reflection profiles ; 04. Solid Earth::04.02. Exploration geophysics::04.02.02. Gravity methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.03. Geodesy::04.03.04. Gravity anomalies ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 94
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    Unknown
    Palynomorphs from a sediment core reveal a sudden remarkably warm Antarctica during the middle Miocene (2009)
    Geological Society of America
    Details
    Publication Date: 2017-04-04
    Description: An exceptional triple palynological signal (unusually high abundance of marine, freshwater, and terrestrial palynomorphs) recovered from a core collected during the 2007 ANDRILL (Antarctic geologic drilling program) campaign in the Ross Sea, Antarctica, provides constraints for the Middle Miocene Climatic Optimum. Compared to elsewhere in the core, this signal comprises a 2000-fold increase in two species of dinoflagellate cysts, a synchronous fivefold increase in freshwater algae, and up to an 80-fold increase in terrestrial pollen, including a proliferation of woody plants. Together, these shifts in the palynological assemblages ca. 15.7 Ma ago represent a relatively short period of time during which Antarctica became abruptly much warmer. Land temperatures reached 10 °C (January mean), estimated annual sea-surface temperatures ranged from 0 to 11.5 °C, and increased freshwater input lowered the salinity during a short period of sea-ice reduction.
    Description: Published
    Description: 955-958
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Middle Miocene Climatic Optimum ; ANDRILL ; Antarctica ; Palynomorphs ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 95
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    Unknown
    Dike propagation within active central volcanic edifices: constraints from Somma-Vesuvius, Etna and analogue models (2009)
    Springer-Verlag
    Details
    Publication Date: 2017-04-04
    Description: Dikes within stratovolcanoes are commonly expected to have radial patterns. However, other patterns may also be found, due to regional stresses, magmatic reservoirs and topographic variations. Here, we investigate dike patterns within volcanic edifices by studying dike and fissure complexes at Somma-Vesuvius and Etna (Italy) using analogue models. At the surface, the dikes and fissures show a radial configuration. At depths of tens to several hundreds of metres, in areas exposed by erosion, tangential and oblique dikes are also present. Analogue models indicate that dikes approaching the flanks of cones, regardless of their initial orientation, reorient to become radial (parallel to the maximum gravitational stress). This re-orientation is a significant process in shallow magma migration and may also control the emplacement of dikefed fissures reaching the lower slopes of the volcano.
    Description: This work was partly financed with DPC-INGV LAVA Project.
    Description: Published
    Description: 219-223
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Dike propagation ; Central volcanic edifices ; Stress ; 04. Solid Earth::04.01. Earth Interior::04.01.03. Mantle and Core dynamics ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 96
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    The July-August 2001 eruption of Mt. Etna (Sicily) (2008)
    Springer-Verlag
    Details
    Publication Date: 2017-04-04
    Description: The July-August 2001 eruption of Mt. Etna stimulated widespread public and media interest, caused significant damage to tourist facilities, and for several days threatened the town of Nicolosi on the S flank of the volcano. Seven eruptive fissures were active, five on the S flank between 3050 and 2100 m altitude, and two on the NE flank between 3080 and 2600 m elevation. All produced lava flows over various periods during the eruption, the most voluminous of which reached a length of 6.9 km. Mineralogically the 2001 lavas fall into two distinct groups, indicating that magma was supplied through two different and largely independent pathways, one extending laterally from the central conduit system through radial fissures, the other being a vertically ascending eccentric dike. Furthermore one of the eccentric vents, at 2570 m elevation, was the site of vigorous phreatomagmatic activity as the dike cut through a shallow aquifer, both during the intial and closing stages of the eruption. For six days the magma column feeding this vent was more or less effectively sealed from the aquifer, permitting powerful explosive and effusive magmatic activity. While the eruption was characterized by a highly dynamic evolution, complex interactions between some of the eruptive fissures, and changing eruptive styles, its total volume (~25 x 106 m3 of lava and 5-10 x 106 m3 of pyroclastics) was relatively small in comparison with other recent eruptions of Etna. Effusion rates were calculated on a daily basis and reached peaks of 14-16 m3 s-1 while the average effusion rate at all fissures was about 11 m3 s-1, which is not exceptionally high. The eruption showed a number of peculiar features, but none of these (except the contemporaneous lateral and eccentric activity) represented a significant deviation from Etna's eruptive behavior in the long term. However, the 2001 eruption could be but the first in a series of flank eruptions, some of which might be more voluminous and hazardous. Placed in a long-term context, the eruption confirms a distinct trend, initiated during the past 50 years, toward higher production rates and more frequent eruptions, which might bring Etna back to similar levels of activity as during the early to mid 17th century.
    Description: Published
    Description: 461-476
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Mt. Etna ; 2001 eruption ; Lava flow-field evolution ; Central-lateral vs. eccentric activity ; Phreatomagmatism ; Eruption dynamics ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 97
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    Simultaneous magma and gas eruptions at three volcanoes in southern Italy: an earthquake trigger? (2008)
    Geological Society of America
    Details
    Publication Date: 2017-04-03
    Description: In September 2002, a series of tectonic earthquakes occurred north of Sicily, Italy, followed by three events of volcanic unrest within 150 km. On October 28, 2002, Mt. Etna erupted; on November 3, 2002, submarine degassing occurred near Panarea Island; and on December 28, 2002, Stromboli Island erupted. All of these events were considered unusual: the Mt. Etna NE-rift eruption was the largest in 55 yr, the Panarea degassing was one of the strongest ever detected there, and the Stromboli eruption, which produced a landslide and tsunami, was the largest effusive eruption in 17 yr. Here, we investigate the synchronous occurrence of these clustered unrest events, and develop a possible explanatory model. We compute short-term earthquake-induced dynamic strain changes and compare them to long-term tectonic effects. Results suggest that the earthquake-induced strain changes exceeded annual tectonic strains by at least an order of magnitude. This agitation occurred in seconds, and may have induced fluid and gas pressure migration within the already active hydrothermal and magmatic systems.
    Description: In press
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.1. Fisica dei terremoti
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: open
    Keywords: earthquake trigger ; magma and gas eruptions ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 98
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    What makes flank eruptions? The 2001 Etna eruption and its possible triggering mechanisms (2008)
    Springer-Verlag
    Details
    Publication Date: 2017-04-04
    Description: Most flank eruptions within a central stratovolcano are triggered by lateral draining of magma from its central conduit, and only few eruptions appear to be independent of the central conduit. In order to better highlight the dynamics of flank eruptions in a central stratovolcano, we review the eruptive history of Etna over the last 100 years. In particular, we take into consideration the Mount Etna eruption in 2001, which showed both summit activity and a flank eruption interpreted to be independent from the summit system. The eruption started with the emplacement of a ~N-S trending peripheral dike, responsible for the extrusion of 75% of the total volume of the erupted products. The rest of the magma was extruded through the summit conduit system (SE crater), feeding two radial dikes. The distribution of the seismicity and structures related to the propagation of the peripheral dike and volumetric considerations on the erupted magmas exclude a shallow connection between the summit and the peripheral magmatic systems during the eruption. Even though the summit and the peripheral magmatic systems were independent at shallow depths (〈3 km b.s.l.), petro-chemical data suggest that a common magma rising from depth fed the two systems. This deep connection resulted in the extrusion of residual magma from the summit system and of new magma from the peripheral system. Gravitational stresses predominate at the surface, controlling the emplacement of the dikes radiating from the summit; conversely, regional tectonics, possibly related to N-S trending structures, remains the most likely factor to have controlled at depth the rise of magma feeding the peripheral eruption.
    Description: Published
    Description: 517-529
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Central volcanoes ; Summit and flank eruptions ; Dikes ; Tectonics ; Volcano load ; Mount Etna ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 99
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    Unknown
    Pyroclastic density currents resulting from the interaction of basaltic magma with hydrothermally altered rock: an example from the 2006 summit eruptions of Mount Etna, Italy (2008)
    Springer-Verlag
    Details
    Publication Date: 2017-04-04
    Description: Abstract After 16 months of quiescence, Mount Etna began to erupt again in mid-July 2006. The activity was concentrated at and around the Southeast Crater (SEC), one of the four craters on the summit of Etna, and eruptive activity continued intermittently for 5 months. During this period, numerous vents displayed a wide range of eruptive styles at different times. Virtually all explosive activities took place at vents at the summit of the SEC and on its flanks. Eruptive episodes, which lasted from 1 day to 2 weeks, became shorter and more violent with time. Volcanic activity at these vents was often accompanied by dramatic mass-wasting processes such as collapse of parts of the cone, highly unusual flowage processes involving both old rocks and fresh magmatic material, and magma– water interaction. The most dramatic events took place on 16 November, when numerous rockfalls and pyroclastic density currents (PDCs) were generated during the opening of a large fracture on the SE flank of the SEC cone. The largest PDCs were clearly triggered explosively, and there is evidence that much of the energy was generated during the interaction of intruding magma with wet rocks on the cone’s flanks. The most mobile PDCs traveled up to 1 km from their source. This previously unknown process on Etna may not be unique on this volcano and is likely to have taken place on other volcanoes. It represents a newly recognized hazard to those who visit and work in the vicinity of the summit of Etna.
    Description: A part of this research was funded by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and by the Dipartimento per la Protezione Civile (Italy).
    Description: Published
    Description: 1249–1268
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: open
    Keywords: Mount Etna ; Pyroclastic density currents ; Lava–water interaction ; Hydrothermal alteration ; Hazards ; Volcano instability ; 2006 eruption ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 100
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    Integrated stratigraphy of the Oligocene pelagic sequence in the Umbria-Marche basin (northeastern Apennines, Italy): A potential Global Stratotype Section and Point (GSSP) for the Rupelian/Chattian boundary (2008)
    Geological Society of America
    Details
    Publication Date: 2022-05-04
    Description: The Oligocene represents an important time period from a wide range of perspectives and includes significant climatic and eustatic variations. The pelagic succession of the Umbria-Marche Apennines (central Italy) includes a complete and continuous sequence of marly limestones and marls, with volcaniclastic layers that enable us to construct an integrated stratigraphic framework for this time period. We present here a synthesis of detailed biostratigraphic, magnetostratigraphic, and chemostratigraphic studies, along with geochronologic results from several biotite-rich volcaniclastic layers, which provide the means for an accurate and precise radiometric calibration of the Oligocene time scale. From this study, the interpolated ages for the Rupelian/Chattian stage boundary, located in the upper half of Chron 10n at meter level 188 in the Monte Cagnero section, and corresponding to the O4/O5 planktonic foraminiferal zonal boundary, are 28.36 Ma (paleomagnetic interpolation), 28.27 ± 0.1 Ma (direct radioisotopic dating), and 27.99 Ma (astrochronological interpolation). These ages appear to be slightly younger than those reported in recent chronostratigraphic time scale compilations. The Monte Cagnero section is a potential candidate for defining the Chattian Global Stratotype Section and Point (GSSP) and some reliable criteria are here proposed for marking the Rupelian/Chattian boundary according to International Union of Geological Sciences (IUGS) recommendations.
    Description: Published
    Description: 487-511
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Integrated stratigraphy ; Oligocene ; Rupelian/Chattian boundary ; Umbria-Marche Apennines, central Italy ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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