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  • 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism  (13)
  • 04. Solid Earth::04.04. Geology::04.04.09. Structural geology  (12)
  • 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks  (8)
  • Geological Society of America  (17)
  • Elsevier B.V.  (12)
  • MDPI Publishing
  • Nature Publishing Group
  • The Geological Society of London
  • 2010-2014  (32)
Collection
Years
Year
  • 1
    Publication Date: 2020-12-14
    Description: Submarine felsic volcanoes are dominated by hyaloclastic piles hundreds of meters thick, the origin of which, in terms of how and when they form, is far from being completely understood. Here we present a study of the thermal remanent magnetization of the Miocene high-K dacitic El Barronal hyaloclastites (Cabo de Gata, Spain), showing that their formation is dominated by in situ fragmentation with small or negligible transportation and/or rotation of different clasts after their formation. Data indicate that fragmentation progressed down to 210–390 °C, well below the glass-transition temperature estimated at 560–750 ºC depending on the water content of the high-K dacite. Hence, hyaloclastite fragmentation in thick lavas may occur over most of the cooling history, as a result of the progressive access of sea water toward the lava interior by development of a complex network of contraction fractures.
    Description: Published
    Description: 87-90
    Description: 1V. Storia e struttura dei sistemi vulcanici
    Description: JCR Journal
    Description: restricted
    Keywords: hyaloclastite ; volcanic fragmentation ; thermal magnetization ; Cabo de Gata ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2022-10-14
    Description: Faial is one of the most volcanically active islands of the Azores Archipelago. Historical eruptions occurred on the Capelo Peninsula (westernmost sector of the island) during A.D. 1672–1673 and more recently in A.D. 1957–1958. The other exposed volcanic products of the peninsula are so far loosely dated within the Holocene. Here, we present a successful attempt to correlate scoria cones and lava flows yielded by the same eruption on the Capelo Peninsula using paleomagnetic data from 31 sites (10 basaltic scoriae, 21 basaltic lava flows). In the investigated products, we recognize at least six prehistoric clusters of volcanic activity, whereas 11 lava sites are correlated with four scoria cones. Dating was conducted by comparing our paleomagnetic directions with relocated Holocene reference curves of the paleosecular variation of the geomagnetic field from France and the UK. We find that the studied volcanic rocks exposed on the Capelo Peninsula are younger than previously believed, being entirely formed in the last 8 k.y., and that the activity intensified over the last 3 k.y. Our study confirms that paleomagnetism is a powerful tool for unraveling the chronology and characteristics of Holocene activity at volcanoes where geochronological age constraints are still lacking.
    Description: Published
    Description: 1164–1180
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: paleomagnetism ; lava ; Azores ; historical volcanic eruptions ; 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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  • 3
    Publication Date: 2021-04-07
    Description: According to the literature, the Adana Basin, at the easternmost part of the Mediterranean Basin in southern Turkey, records the Pliocene stage with shallow-marine to fluvial deposits. Our micropalaeontological analysis of samples from the Adana Basin reveal Late Lago–Mare biofacies with Paratethyan ostracod assemblages pertaining to the Loxocorniculina djafarovi zone. Grey clays rich in planktonic foraminifera lie above the Lago–Mare deposits. Within the grey clays, the continuous occurrence of the calcareous nannofossil Reticulofenestra zancleana and the base of the Reticulofenestra pseudoumbilicus paracme points to an Early Zanclean age (5.332–5.199 Ma). Both ostracod and benthic foraminifera indicate epibathyal and bathyal environments. 87Sr/86Sr measurements on planktonic and benthic foraminifera fall below the mean global ocean value for the Early Zanclean, indicating potentially insufficient mixing of low 87Sr/86Sr Mediterranean brackish ‘Lago–Mare’ water with the global ocean in the earliest Pliocene.We utilize the ages and palaeodepths of the marine sediments together with their modern elevations to determine uplift rates of the Adana Basin of 0.06 to 0.13 mm a21 since 5.2–5.3 Ma (total uplift of 350–650 m) from surface data, and 0.02–0.13 mm a21 since c. 1.8 Ma (total uplift of 30–230 m) from subsurface data.
    Description: Published
    Description: 3.2. Tettonica attiva
    Description: N/A or not JCR
    Description: restricted
    Keywords: Lago–Mare deposits ; Adana Basin ; southern Turkey ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 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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  • 4
    Publication Date: 2017-04-04
    Description: Vesicle size distributions in two and three dimensions of two samples were independently measured by three different researchers to investigate whether or not such measurements are reproducible. Additionally, two different software programs were used to measure the three-dimensional vesicle size distributions: the 3D Object Counter plugin for ImageJ and Blob3D. Manual thresholding by each of the authors produced similar results for both samples using both programs; however, use of the automatic, maximum entropy technique for thresholding produced measurably different results because it did not discriminate between vesicles and plagioclase crystals in one case and between vesicles and some cracks in another. Use of asymmetric erosion and dilation processes on the images is shown to affect the vesicle size distribution, but it does not have a significant effect on the power-law exponent that describes intermediate-sized vesicles or on the vesicle number density in these samples. However, such a technique is not recommended.
    Description: Published
    Description: 70-78
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Volcanic rocks ; vesicle counting ; reproducibility ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2017-04-04
    Description: The ANtarctic geological DRILLing program (ANDRILL) successfully recovered 1138.54 m of core from drillhole, AND-2A, in the Ross Sea sediments (Antarctica). The core is composed of terrigenous claystones, siltstones, sandstones, conglomerates, breccias, and diamictites with abundant volcanic material. In this work we present sedimentological, morphoscopic, petrographic, and geochemical data on pyroclasts recovered from core AND-2A, which provide insights on eruption styles, volcanic sources, and environments of deposition. One pyroclastic fall deposit, 12 resedimented volcaniclastic deposits and 14 volcanogenic sedimentary deposits record a history of intense explosive volcanic activity in southern Victoria Land during the Early Miocene. Tephra were ejected during Subplinian and Plinian eruptions fed by trachytic to rhyolitic magmas and during Strombolian to Hawaiian eruptions fed by basaltic to mugearitic magmas in submarine/subglacial to subaerial environments. The long-lived Mt. Morning eruptive centre, located c. 80 km south of the drillsite, was recognized as the probable volcanic source for these products on the basis of volcanological, geochemical, and age constraints. The study of tephra in the AND-2A core provides important paleoenvironment information by revealing that the deposition of primary and moderately reworked tephra occurred in a proglacial setting under generally open water marine conditions.
    Description: Published
    Description: 1342-1355
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: partially_open
    Keywords: Antarctica ; Volcaniclastic sediments ; Paleoenvironment ; Mt. Morning ; Victoria Land Basin ; 02. Cryosphere::02.03. Ice cores::02.03.05. Paleoclimate ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
    Publication Date: 2021-01-27
    Description: X-ray computed microtomography is an excellent tool for the three-dimensional analysis of rock microstructure. Digital images are acquired, visualized, and processed to identify and measure several discrete features and constituents of rock samples, by means of mathematical algorithms and computational methods. In this paper, we present digital images of volcanic rocks collected with X-ray computed microtomography techniques and studied by means of a software library, called Pore3D, custom-implemented at the Elettra Synchrotron Light Laboratory of Trieste (Italy). Using the Pore3D software, we analyzed the fabrics and we quantified the characteristics of the main constituents (vesicles, crystals, and glassy matrix) of four different types of pyroclasts: frothy pumice, tube pumice, scoria, and “crystalline” scoria. We identified the distinctive features of these different types of volcanic rocks. The frothy pumices show vesicles that coalesce in isotropic aggregates, especially toward the sample interior, while the scoriae have a low porosity and an abundance of isolated vesicles. In the “crystalline” scoria sample most of the vesicle separation is due to the presence of crystals of different types, while the tube pumice shows an anisotropic distribution of vesicles and crystals at the microscale, as also observed at the scale of the hand sample. Quantitative analysis and textural information may supply an additional tool to investigate the eruptive processes and the origin of volcanic rocks.
    Description: Published
    Description: 793-804
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: X-ray tomography ; 3D imaging ; volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
    Publication Date: 2020-11-18
    Description: Morphologic data for 147 cinder cones in southern Guatemala andwestern El Salvador are comparedwith data from the San Francisco volcanic field, Arizona (USA), Cima volcanic field, California (USA), Michoácan–Guanajuato volcanic field, Mexico, and the Lamongan volcanic field, East Java. The Guatemala cones have an average height of 110+/-50 m, an average basal diameter of 660+/-230 m and an average top diameter of 180+/-150 m. The generalmorphology of these cones can be described by their average cone angle of slope (24+/-7), average heightto- radius ratio (0.33+/-0.09) and their flatness (0.24+/-0.18). Although the mean values for the Guatemalan cones are similar to those for other volcanic fields (e.g., San Francisco volcanic field, Arizona; Cima volcanic field, California; Michoácan–Guanajuato volcanic field, Mexico; and Lamongan volcanic field, East Java), the range of morphologies encompasses almost all of those observed worldwide for cinder cones. Three new 40Ar/39Ar age dates are combined with 19 previously published dates for cones in Guatemala and El Salvador. There is no indication that the morphologies of these cones have changed over the last 500–1000 ka. Furthermore, a re-analysis of published data for other volcanic fields suggests that only in the Cima volcanic field (of those studied) is there clear evidence of degradation with age. Preliminary results of a numerical model of cinder cone growth are used to show that the range of morphologies observed in the Guatemalan cinder cones could all be primary, that is, due to processes occurring at the time of eruption.
    Description: Support for Walker was provided by NSF MARGINS grant OCE- 0405666.
    Description: Published
    Description: 39-52
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: open
    Keywords: cinder cones ; morphology ; age dating ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
    Publication Date: 2017-04-04
    Description: Magnetotactic bacteria intracellularly biomineralize magnetite of an ideal grain size for recording palaeomagnetic signals. However, bacterial magnetite has only been reported in a few pre-Quaternary records because progressive burial into anoxic diagenetic environments causes its dissolution. Deep-sea carbonate sequences provide optimal environments for preserving bacterial magnetite due to low rates of organic carbon burial and expanded pore-water redox zonations. Such sequences often do not become anoxic for tens to hundreds of metres below the seafloor. Nevertheless, the biogeochemical factors that control magnetotactic bacterial populations in such settings are not well known. We document the preservation of bacterial magnetite, which dominates the palaeomagnetic signal throughout Eocene pelagic carbonates from the southern Kerguelen Plateau, Southern Ocean. We provide evidence that iron fertilization, associated with increased aeolian dust flux, resulted in surface water eutrophication in the late Eocene that controlled bacterial magnetite abundance via export of organic carbon to the seafloor. Increased flux of aeolian ironbearing phases also delivered iron to the seafloor, some of which became bioavailable through iron reduction. Our results suggest that magnetotactic bacterial populations in pelagic settings depend crucially on particulate iron and organic carbon delivery to the seafloor.
    Description: Published
    Description: 441-452
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Magnetotactic bacteria ; Magnetofossils ; Magnetite ; Productivity ; Iron ; Organic carbon ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.09. Environmental magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
    Publication Date: 2017-04-04
    Description: Many volcanic edifices are subject to flank failure, usually produced by a combination of events, rather than any single process. From a dynamic point of view, the cause of collapse can be divided into factors that contribute to an increase in shear stress, and factors that contribute to the reduction in the friction coefficient μ of a potential basal failure plane. We study the potential for flank failure at Mount Etna considering a schematic section of the eastern flank, approximated by a wedge-like block. For such geometry, we perform a (steady state) limit equilibrium analysis: the resolution of the forces parallel to the possible basal failure plane allows us to determine the total force acting on the potentially unstable wedge. An estimate of the relative strength of these forces suggests that, in first approximation, the stability is controlled primarily by the balance between block weight, lithostatic load and magmatic forces. Any other force (sea load, hydrostatic uplift, and the uplift due to mechanical and thermal pore-fluid pressure) may be considered of second order. To study the model sensitivity, we let the inferred slope α of the basal surface failure vary between −10° and 10°, and consider three possible scenarios: no magma loading, magmastatic load, and magmastatic load with magma overpressure. We use error propagation to include in our analysis the uncertainties in the estimates of the mechanics and geometrical parameters controlling the block equilibrium. When there is no magma loading, the ratio between destabilizing and stabilizing forces is usually smaller than the coefficient of friction of the basal failure plane. In the absence of an initiating mechanism, and with the nominal values of the coefficient of friction μ = 0.7 ± 0.1 proposed, the representative wedge will remain stable or continue to move at constant speed. In presence of magmastatic forces, the influence of the lateral restraint decreases. If we consider the magmastatic load only, the block will remain stable (or continue to move at constant speed), unless the transient mechanical and thermal pressurization significantly decrease the friction coefficient, increasing the instability of the flank wedge for α 〉 5° (seaward dipping decollement). When the magma overpressure contribution is included in the equilibrium analysis, the ratio between destabilizing and stabilizing forces is of the same order or larger than the coefficient of friction of the basal failure plane, and the block will become unstable (or accelerate), especially in the case of the reduction in friction coefficient. Finally, our work suggests that the major challenge in studying flank instability at Mount Etna is not the lack of an appropriate physical model, but the limited knowledge of the mechanical and geometrical parameters describing the block equilibrium.
    Description: This work was funded by Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the Italian Dipartimento per la Protezione Civile (DPC) (DPC-INGV project V4 “Flank”).
    Description: Published
    Description: 153-164
    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: Etna ; dike intrusion ; flank instability ; poro-elasticity ; analytical modelling ; 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::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 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::05.01. Computational geophysics::05.01.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 15
    Publication Date: 2017-04-04
    Description: Present understanding of Antarctic climate change during the Early to Mid-Miocene, including major cycles of glacial expansion and contraction, relies in large part on stable isotope proxies from deep sea core drilling. Here, we summarize the lithostratigraphy of the ANDRILL Southern McMurdo Sound Project drillcore AND- 2A. This core offers a hitherto unavailable ice-proximal stratigraphic archive from a high-accommodation continental margin setting, and provides clear evidence of repeated fluctuations in climate, ice expansion/ contraction and attendant sea-level change over the period c. 20.2–14.2 Ma, with a more fragmentary record of Late Miocene and Pliocene time. The core is divided into seventy-four high-frequency (fourth- or fifthorder) glacimarine sequences recording repeated advances and retreats of glaciers into and out of the Victoria Land Basin. The section can be resolved into thirteen longer-term, composite (third-order) sequences, which comprise packages of higher frequency sequences that show a consistent stratigraphic stacking pattern (Stratigraphic Motif). The distribution of the six recognized motifs indicates intervals of less and more iceproximal, and temperate to subpolar/polar climate, through the Miocene period. The core demonstrates a dynamic climate regime throughout the Early to Mid-Miocene that may be correlated to some previouslyrecognized events such as the Mid-Miocene Climatic Optimum, and provides a detailed reference point from which to evaluate stable isotope proxy records from the deep-sea.
    Description: Published
    Description: 337-351
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Miocene ; Antarctica ; Sequence stratigraphy ; Cyclicity ; Mid-Miocene Climatic Optimum ; ANDRILL SMS project ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.09. Environmental magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 16
    Publication Date: 2017-04-04
    Description: The ANDRILL McMurdo Ice Shelf initiative recovered a 1285-m-long core (AND-1B) composed of cyclic glacimarine sediments with interbedded volcanic deposits. The thickest continuous volcanic sequence by far is ∼175 m long and is found at mid-core depths from 584.19 to 759.32 m below seafloor. 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 scanning electron microscopy–energy dispersive spectroscopy 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 data set 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 offshore setting.
    Description: Published
    Description: 524-536
    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: reserved
    Keywords: Antarctica ; Andrill ; Ice-Volcano interactions ; Submarine Volcanism ; Volcanoclastic rocks ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
    Publication Date: 2022-06-14
    Description: In the past few years, a wealth of paleomagnetic data gathered from Neogene sediments consistently showed that since ca. 10 Ma the Calabria terrane coherently drifted ~500 km ESE-ward from the Sardinian margin, and rotated 15 –20 clockwise (CW) as a rigid microplate between 2 and 1 Ma. Here we report on a high-resolution paleomagnetic investigation of the Crotone forearc basin of northern Calabria. The integrated calcareous plankton biostratigraphy indicates early Pliocene (Zanclean) to late early Pleistocene (Calabrian) ages for 29 successful paleomagnetic sites and/or sections. Unexpectedly, four domains undergoing distinct rotations are documented. Two blocks have undergone a CW rotation statistically undistinguishable, for both timing and magnitude, from the rigid Calabria rotation documented in the past. Two additional ~10-km-wide blocks yielded a 30.8 ± 22.5 and 32.0 ± 9.2 post–1.2 Ma counterclockwise rotation, likely due to left-lateral shear along two NW-SE fault zones. We infer that since advanced early Pleistocene times, after the end of the uniform CW rotation, left-lateral strike-slip tectonics disrupted the Calabria terrane, overwhelming a widespread extensional regime accompanying the Calabria drift since late Miocene times. Seismological evidence reveals that only the southern part of the Ionian slab subducting below Calabria is continuous, while beneath northern Calabria a slab window between 100 and 200 km depth is apparent. We suggest that the partial breakoff of the Ionian slab after 1 Ma induced the fragmentation of the Calabria wedge, and that strike-slip faults from the Crotone basin decoupled “inactive” northern Calabria from southern Calabria, still drifting towards the trench.
    Description: Published
    Description: 925–933
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Calabria ; Crotone basin ; paleomagnetism ; rotations ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 20
    Publication Date: 2017-04-04
    Description: We conducted geophysical–geochemical measurements on a ∼2 kmN–S profile cutting across the Pernicana Fault, one of the most active tectonic features on the NE flank of Mt. Etna. The profile passes from the unstable E flank of the volcano (to the south) to the stable N flank and significant fluctuations in electrical resistivity, self-potential, and soil gas emissions (CO2, Rn and Th) are found. The detailed multidisciplinary analysis reveals a complex interplay between the structural setting, uprising hydrothermal fluids, meteoric fluids percolating downwards, ground permeability, and surface topography. In particular, the recovered fluid circulation model highlights that the southern sector is heavily fractured and faulted, allowing the formation of convective hydrothermal cells. Although the existence of a hydrothermal system in a volcanic area does not surprise, these results have great implications in terms of flank dynamics at Mt. Etna. Indeed, the hydrothermal activity, interacting with the Pernicana Fault activity, could enhance the flank instability. Our approach should be further extended along the full extent of the boundary between the stable and unstable sectors of Etna for a better evaluation of the geohazard in this active tectonic area.
    Description: This work was partly financed by the DPC-INGV FLANK and LAVA Projects.
    Description: Published
    Description: 137–142
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: Pernicana Fault ; fluid circulation ; structural geology ; Etna ; magnetic ; electrical methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.02. Exploration geophysics::04.02.04. Magnetic and electrical methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 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::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
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  • 21
    Publication Date: 2017-04-04
    Description: The southernmost segment of the Andes of southern Patagonia and Tierra del Fuego forms a ~700 km long orogenic re-entrant with an interlimb angle of ~90° known as Patagonian orocline. No reliable paleomagnetic evidence has been gathered so far to assess whether this great orogenic bend is a primary arc formed over an articulated paleomargin, or is due to bending of a previously less curved (or rectilinear) chain. Here we report on an extensive paleomagnetic and anisotropy of magnetic susceptibility (AMS) study carried out on 22 sites (298 oriented cores), predominantly sampled in Eocene marine clays from the external Magallanes belt of Tierra del Fuego. Five sites (out of six giving reliable paleomagnetic results) containing magnetite and subordinate iron sulphides yield a positive fold test at the 99% significance level, and document no significant rotation since ~50 Ma. Thus, the Patagonian orocline is either a primary bend, or an orocline formed after Cretaceous–earliest Tertiary rotations. Our data imply that the opening of the Drake Passage between South America and Antarctica (probably causing the onset of Antarctica glaciation and global climate cooling), was definitely not related to the formation of the Patagonian orocline, but was likely the sole consequence of the 32±2 Ma Scotia plate spreading. Well-defined magnetic lineations gathered at 18 sites from the Magallanes belt are sub-parallel to (mostly E–W) local fold axes, while they trend randomly at two sites from the Magallanes foreland. Our and previous AMS data consistently show that the Fuegian Andes were characterized by a N–S compression and northward displacing fold–thrust sheets during Eocene–early Miocene times (50–20 Ma), an unexpected kinematics considering coeval South America–Antarctica relative motion. Both paleomagnetic and AMS data suggest no significant influence from the E–W left-lateral Magallanes–Fagnano strike–slip fault system (MFFS), running a few kilometres south of our sampling sites. We thus speculate that strike–slip fault offset in the Fuegian Andes may range in the lower bound values (~20 km) among those proposed so far. In any case our data exclude any influence of strike–slip tectonics on the genesis of the great orogenic bend called Patagonian orocline.
    Description: In press
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: paleomagnetism ; tectonics ; Patagonian orocline ; Fuegian Andes ; Drake Passage ; Magallanes belt ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 22
    Publication Date: 2017-04-04
    Description: Paleomagnetic and rock magnetic investigation was performed on the 35-m long MD03-2595 CADO (Coring Adélie Diatom Oozes) piston core recovered on the continental rise of the Wilkes Land Basin (East Antarctica). Analysis of the characteristic remanent magnetization (ChRM) inclination record indicates a normal magnetic polarity for the uppermost 34m of the sequence and a distinctive abrupt polarity change at the bottom of the core. This polarity change, which spans a 27 cm thick stratigraphic interval, represents a detailed record of the Matuyama–Brunhes (M–B) transition and it is preceded by a sharp oscillation in paleomagnetic directions that may correlate to the M–B precursor event. Paleomagnetic measurements enable reconstruction of geomagnetic relative paleointensity (RPI) variations, and a high-resolution age model was established by correlating the CADO RPI curve to the available global reference RPI stack, indicating that the studied sequence reaches back to ca. 800 ka with an average sedimentation rate of 4.4 cm/ka. Orbital periodicities (100 ka and 41 ka) were found in the ChRM inclination record, and a significant coherence of ChRM inclination and RPI record around 100 ka suggests that long-term geomagnetic secular variation in inclination is controlled by changes in the relative strength of the geocentric axial dipole and persistent non-dipole components. Moreover, even if the relatively homogeneous rock magnetic parameters and lithofacies throughout the recovered sequence indicates a substantial stability of the East Antarctic Ice Sheet during the middle and late Pleistocene, influence of the 100 ka and 41 ka orbital periodicities has been detected in some rock magnetic parameters, indicating subtle variations in the concentration and grain-size of the magnetic minerals linked to orbital forcing of the global climate.
    Description: In press
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Paleomagnetism ; Relative paleointensity ; Brunhes Chron ; Matuyama–Brunhes precursor ; Antarctica ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 23
    Publication Date: 2017-04-04
    Description: Paleomagnetic and rock magnetic investigation was performed on the 35-m long MD03-2595 CADO (Coring Adélie Diatom Oozes) piston core recovered on the continental rise of the Wilkes Land Basin (East Antarctica). Analysis of the characteristic remanent magnetization (ChRM) inclination record indicates a normal magnetic polarity for the uppermost 34m of the sequence and a distinctive abrupt polarity change at the bottom of the core. This polarity change, which spans a 27 cm thick stratigraphic interval, represents a detailed record of the Matuyama–Brunhes (M–B) transition and it is preceded by a sharp oscillation in paleomagnetic directions that may correlate to the M–B precursor event. Paleomagnetic measurements enable reconstruction of geomagnetic relative paleointensity (RPI) variations, and a highresolution age model was established by correlating the CADO RPI curve to the available global reference RPI stack, indicating that the studied sequence reaches back to ca. 800 ka with an average sedimentation rate of 4.4 cm/ka. Orbital periodicities (100 ka and 41 ka) were found in the ChRM inclination record, and a significant coherence of ChRM inclination and RPI record around 100 ka suggests that long-term geomagnetic secular variation in inclination is controlled by changes in the relative strength of the geocentric axial dipole and persistent non-dipole components. Moreover, even if the relatively homogeneous rock magnetic parameters and lithofacies throughout the recovered sequence indicates a substantial stability of the East Antarctic Ice Sheet during the middle and late Pleistocene, influence of the 100 ka and 41 ka orbital periodicities has been detected in some rock magnetic parameters, indicating subtle variations in the concentration and grain-size of the magnetic minerals linked to orbital forcing of the global climate.
    Description: Published
    Description: 72-86
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Paleomagnetism ; Relative paleointensity ; Brunhes Chron ; Matuyama–Brunhes precursor ; Antarctica ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism
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  • 24
    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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  • 25
    Publication Date: 2017-04-04
    Description: Many volcanic edifices are subject to flank failure, usually produced by a combination of events, rather than any single process. From a dynamic point of view, the cause of collapse can be divided into factors that contribute to an increase in shear stress, and factors that contribute to the reduction in the friction coefficient μ of a potential basal failure plane. We study the potential for flank failure at Mount Etna considering a schematic section of the eastern flank, approximated by a wedge-like block. For such geometry, we perform a (steady state) limit equilibrium analysis: the resolution of the forces parallel to the possible basal failure plane allows us to determine the total force acting on the potentially unstable wedge. An estimate of the relative strength of these forces suggests that, in first approximation, the stability is controlled primarily by the balance between block weight, lithostatic load and magmatic forces. Any other force (sea load, hydrostatic uplift, and the uplift due to mechanical and thermal pore-fluid pressure) may be considered of second order. To study the model sensitivity, we let the inferred slope α of the basal surface failure vary between −10° and 10°, and consider three possible scenarios: no magma loading, magmastatic load, and magmastatic load with magma overpressure. We use error propagation to include in our analysis the uncertainties in the estimates of the mechanics and geometrical parameters controlling the block equilibrium. When there is no magma loading, the ratio between destabilizing and stabilizing forces is usually smaller than the coefficient of friction of the basal failure plane. In the absence of an initiating mechanism, and with the nominal values of the coefficient of friction μ=0.7±0.1 proposed, the representative wedge will remain stable or continue to move at constant speed. In presence of magmastatic forces, the influence of the lateral restraint decreases. If we consider the magmastatic load only, the block will remain stable (or continue to move at constant speed), unless the transient mechanical and thermal pressurization significantly decrease the friction coefficient, increasing the instability of the flank wedge for αN5° (seaward dipping decollement). When the magma overpressure contribution is included in the equilibrium analysis, the ratio between destabilizing and stabilizing forces is of the same order or larger than the coefficient of friction of the basal failure plane, and the block will become unstable (or accelerate), especially in the case of the reduction in friction coefficient. Finally, our work suggests that the major challenge in studying flank instability at Mount Etna is not the lack of an appropriate physical model, but the limited knowledge of the mechanical and geometrical parameters describing the block equilibrium.
    Description: This work was funded by Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the Italian Dipartimento per la Protezione Civile (DPC) (DPC-INGV project V4 “Flank”).
    Description: In press
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; dike intrusion ; flank instability ; poro-elasticity ; analytical modelling ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 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::04.07.99. 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::04.08.03. 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::05.01. Computational geophysics::05.01.99. General or miscellaneous ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous
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  • 26
    Publication Date: 2017-04-04
    Description: The Vrica section in Calabria, southern Italy, was the global stratotype for the Pliocene–Pleistocene boundary until this boundary was redefined in 2009. Several paleomagnetic investigations have been carried out at Vrica to determine the age of the formerly defined Pliocene–Pleistocene boundary, which was a key calibration point for the astronomical polarity timescale(APTS). Each study has documented a complex polarity pattern at and above the top of the Olduvai subchron and in relation to the existence of the so-called Vrica subchron. When constructing the APTS, two alternative interpretations for the Vrica section were proposed,neither of which could be conclusively supported. Authigenic growth of magnetic iron sulphide minerals was proposed to explain the complex magnetic polarity record. Availability of a fresh 50-m sediment core enabled us to test this possibility. Our magnetostratigraphic record is similar to that of previous studies, but it is also complex above the Olduvai subchron. We confirm abundant occurrences of authigenic greigite and pyrrhotite, along with detrital titanomagnetite. Authigenic monoclinic pyrrhotite indicates growth significantly later than deposition, and greigite can grow at any time during diagenesis, depending on the availability of dissolved iron and sulphide. The spatially variable magnetic polarity pattern at Vrica is therefore interpreted to have resulted from post-depositional magnetic iron sulphide formation at variable times. Tectonism along the Calabrian arc provides a plausible mechanism for forcing reducing fluids through the sediments, thereby supplying the dissolved ions needed to produce late diagenetic sulphide growth and remagnetization. The complex magnetostratigraphic record at Vrica was taken into account when the APTS was developed, and alternative interpretations result in a maximum age difference of 50 kyr for the upper Olduvai reversal. Our results therefore do not undermine the APTS. Rather, they explain the complex magnetic polarity pattern at this globally important location and highlight the importance of remagnetization processes in such sediments.
    Description: Published
    Description: 98-111
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Pliocene ; Pleistocene ; Vrica ; magnetostratigraphy ; Olduvai ; remagnetization ; greigite ; pyrrhotite ; methanehydrate ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 27
    Publication Date: 2017-04-04
    Description: Morphologic data for 147 cinder cones in southernGuatemala andwestern El Salvador are comparedwith data from 21 the San Francisco volcanic field, Arizona (USA), Cima volcanic field, California (USA), Michoácan–Guanajuato 22 volcanic field, Mexico, and the Lamongan volcanic field, East Java. The Guatemala cones have an average height of 23 110+/−50m, an average basal diameter of 660+/−230m and an average top diameter of 180+/−150m. The 24 generalmorphology of these cones can be described by their average cone angle of slope (24+/−7), average height- 25 to-radius ratio (0.33+/−0.09) and their flatness (0.24+/−0.18). Although the mean values for the Guatemalan 26 cones are similar to those for other volcanic fields (e.g., San Francisco volcanic field, Arizona; Cima volcanic field, 27 California; Michoácan–Guanajuato volcanic field, Mexico; and Lamongan volcanic field, East Java), the range of 28 morphologies encompasses almost all of those observed worldwide for cinder cones. 29 Three new 40Ar/39Ar age dates are combined with 19 previously published dates for cones in Guatemala and El 30 Salvador. There is no indication that the morphologies of these cones have changed over the last 500–1000 ka. 31 Furthermore, a re-analysis of published data for other volcanic fields suggests that only in the Cima volcanic field (of 32 those studied) is there clear evidence of degradation with age. 33 Preliminary results of a numerical model of cinder cone growth are used to show that the range of morphologies 34 observed in the Guatemalan cinder cones could all be primary, that is, due to processes occurring at the time of 35 eruption.
    Description: Support for Walker was provided by NSF MARGINS grant OCE-0405666.
    Description: In press
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: cinder cones ; morphology ; age dating ; 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::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 28
    Publication Date: 2017-04-04
    Description: The Eocene climatic system experienced an important transition from warm Paleocene greenhouse to icehouse Oligocene conditions.This transition could first appear as a long-term cooling trend but, at an up-close look, this period is a complex combination of climatic events and,for most of them, causes and consequences are still not fully characterized. In this context, a study has been carried out on the middle Eocene sedimentary succession of the Contessa Highway section, central Italy, which is proposed as the Global Stratotype Section and Point(GSSP)for the Lutetian/Bartonian boundary at the top of the Chron 19n, with an astronomically calibrated age of 41.23 Ma. Through a cyclostratigraphic analysis of the rhythmic sedimentary alternations and combination with the results of time series analysis of the proxy record, we provide an orbital tuning of the middle Eocene and astronomical calibration of the bio-magnetostratigraphic events (particularly for the C19n/C18r Chronboundary) recognized at the Contessa Highway section.
    Description: Published
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: environmental magnetism ; middle Eocene epoch ; cyclostratigraphy ; orbital tuning ; Lutetian/Bartonian boundary ; Contessa Highway section ; Italy ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 29
    Publication Date: 2017-04-04
    Description: In the past few years, a wealth of paleomagnetic data gathered from Neogene sediments consistently showed that since ca. 10 Ma the Calabria terrane coherently drifted ~500 km ESE-ward from the Sardinian margin, and rotated 15°–20° clockwise (CW) as a rigid microplate between 2 and 1 Ma. Here we report on a high-resolution paleomagnetic investigation of the Crotone forearc basin of northern Calabria. The integrated calcareous plankton biostratigraphy indicates early Pliocene (Zanclean) to late early Pleistocene (Calabrian) ages for 29 successful paleomagnetic sites and/or sections. Unexpectedly, four domains undergoing distinct rotations are documented. Two blocks have undergone a CW rotation statistically undistinguishable, for both timing and magnitude, from the rigid Calabria rotation documented in the past. Two additional ~10-km-wide blocks yielded a 30.8° ± 22.5° and 32.0° ± 9.2° post–1.2 Ma counterclockwise rotation, likely due to left-lateral shear along two NW-SE fault zones. We infer that since advanced early Pleistocene times, after the end of the uniform CW rotation, left-lateral strike-slip tectonics disrupted the Calabria terrane, overwhelming a widespread extensional regime accompanying the Calabria drift since late Miocene times. Seismological evidence reveals that only the southern part of the Ionian slab subducting below Calabria is continuous, while beneath northern Calabria a slab window between 100 and 200 km depth is apparent. We suggest that the partial breakoff of the Ionian slab after 1 Ma induced the fragmentation of the Calabria wedge, and that strike-slip faults from the Crotone basin decoupled “inactive” northern Calabria from southern Calabria, still drifting towards the trench.
    Description: In press
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Calabria ; Crotone basin ; paleomagnetism ; rotations ; 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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  • 30
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 31
    Publication Date: 2021-11-09
    Description: Rapidly developing methods of digital acquisition, visualization and analysis allow highly detailed outcrop models to be constructed, and used as analogues to provide quantitative information about sedimentological and structural architectures from reservoir to subseismic scales of observation. Terrestrial laser-scanning (lidar) and high precision Real-Time Kinematic GPS are key survey technologies for data acquisition. 3D visualization facilities are used when analysing the outcrop data. Analysis of laser-scan data involves picking of the point-cloud to derive interpolated stratigraphic and structural surfaces. The resultant data can be used as input for object-based models, or can be cellularized and upscaled for use in grid-based reservoir modelling. Outcrop data can also be used to calibrate numerical models of geological processes such as the development and growth of folds, and the initiation and propagation of fractures.
    Description: Published
    Description: 87–98
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: N/A or not JCR
    Description: reserved
    Keywords: Laser-Scanning ; Outcrop analogues ; Reservoirs ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 32
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    Unknown
    Geological Society of America
    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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