ALBERT

Description: The geodynamic significance of continental volcanoes located far from the plate boundaries remains highly controversial as exemplified by contrasting models that favor either a deep mantle plume rooted from the base of the mantle or, alternatively, the shallower subduction or lithospheric-related processes. The Changbaishan (also referred to as Paektusan or Baekdusan) volcanic field (CHVF), located in the interior of eastern Eurasian continent, provides a good opportunity to constrain the magma origin and geodynamic mechanism governing continental intraplate volcanism. Here, we review the volcanic geology, eruptive history, geochemical data on volcanic rocks and released gases and geophysical observations of the Changbaishan volcanoes with the aim to (a) reconstruct temporal and spatial evolution of eruptive activities, (b) identify source of the primary magmas, (c) delineate magma evolution in the crust, (d) highlight geodynamic significance of the CHVF volcanism, (e) characterize crustal magmatic structure, and (f) analyze recent dynamics with a focus on the 2002–2005 unrest episode at Tianchi caldera, the only active volcano in the area (last eruption in 1903 CE). The eruptive activities of the Changbaishan volcanoes can be divided into three main stages: (1) central vent and fissure eruptions of basaltic magmas started approximately in Pliocene and culminated in Early Pleistocene (ca. 5–1 Ma), forming a shield-like lava plateau; (2) multi-stage eruptions of voluminous silicic (and minor intermediate) magmas constructed cones of the polygenetic volcanoes (e.g., Tianchi, Wangtian'e and Namphothe) between Late Pliocene and Pleistocene (3.14–0.01 Ma); and (3) explosive silicic eruptions [e.g., the Millennium eruption (ME) in 946 CE] during Holocene dominated the Tianchi volcano and led to the formation of its summit caldera. Small-scale eruptions of basaltic magmas from monogenetic scoria cones (and minor fissures) were coeval with the Tianchi cone-construction stage (ca. 1–0.01 Ma). The elemental and Sr-Nd-Pb isotopic characteristics of the Changbaishan basalts indicate an enriched, heterogeneous mantle source with components from depleted mantle (DM), enriched mantle 1 (EM1) and subduction-related materials (e.g., recycled oceanic crust and sediments). The interaction between the DM-like peridotite and carbonatite melts released by subducted oceanic slab in the mantle transition zone (MTZ) led to the formation of carbonated peridotite characterized by low δ26Mg values. By contrast, origin of the EM1-like components remains highly debated. The alkaline basalts and intermediate to silicic volcanic rocks from the polygenetic volcanoes constitute an integrated spectrum of magma composition controlled by closed system fractionation according to their element co-variations and uniform Sr-Nd-Pb isotopic compositions. Subordinate mingling between trachyte and comendite has been reported only for the ME at Tianchi caldera. The occurrence of a big mantle wedge (BMW) with a continuous stagnant Pacific slab in the MTZ is responsible for origin of the Changbaishan volcanoes. On the basis of subduction dynamics of the Pacific plate, we present a Late Cenozoic geodynamic framework of NE Asia, which can account for formation of the present-day BMW system via: (a) shallow-angle subduction (55–25 Ma), (b) slab rollback and sinking into the MTZ together with trench retreat (25–15 Ma), and (c) slab bottoming, thickening and flattening in the MTZ (15–0 Ma). Constraints from reconstructed plate motion history, numerical simulation and present-day geophysical observation of the BMW lend support to our geodynamic model, which reconciles well with the Izanagi slab breakoff, development of the Japan Sea and Late Cenozoic continental intraplate volcanism in NE China. In response to the Rayleigh-Taylor instability, a MTZ-derived plume incorporating fragments of carbonated peridotite, EM1- like components and the Pacific slab-derived materials ascended and experienced decompression partial melting at shallow depths to feed the Changbaishan volcanism. From the perspective of magma origin and geodynamic mechanism, the Changbaishan volcanoes can shed light on the potential relationships between origin of continental intraplate volcanism and deep subduction of oceanic lithosphere. The spatial distribution of the Changbaishan volcanoes shows that the magmas ascended along a NW-SE trending, strike-slip fault oriented perpendicularly to the major faults delimiting the Songliao Basin, NE China. This interpretation is consistent with the 2009–2013 epicenters of tectonic earthquakes, also suggesting a NW-SE trending, buried and seismically active deep fault in the crust. Geophysical and petrological constraints indicate the presence of magma reservoirs at crustal depth beneath the active Tianchi volcano, which are likely to have high thermal state and act as the source of heat and material for shallow hydrothermal system. In consideration of magma origin from the MTZ-derived plume, the volatile outgassing from the Tianchi volcano associated with deep subduction of the Pacific plate represents an important mechanism for liberating volatile elements (especially carbon) from Earth's interior to the exosphere. Tianchi caldera suffered an unrest episode between 2002 and 2005, as evidenced by increased shallow seismicity, surface uplift and changes in chemical and isotopic composition of the hydrothermal gases. Such volcanic unrest was triggered by pressurization of a 2–6 km depth magma reservoir, from which magmatic volatiles were released into shallow hydrothermal system. Tianchi caldera shows different types of hazards related to volcanic, tectonic, geomorphological and hydrological processes. Further monitoring and additional volcanological data, especially those on eruptive dynamics of the past eruptions, should be collected to better constrain the potential hazards of future eruptions and to improve early warning management.

Description: Published

Description: 19-52

Description: 1V. Storia eruttiva

Description: JCR Journal

Description: The twentieth century has been described (e.g., Piskorski 2015 ) as a century of displacement. While globally the comparative scale of involuntary population movement may not have diff ered signifi cantly from earlier centuries, its perception has changed radically, leading in the early twenty- fi rst century to the dramatic resurgence of xenophobic populism across Europe and beyond (see Kaya 2017 ; De Cesari and Kaya 2019). Throughout the ‘refugee crisis’ of the 2010s, the German government’s moderate policy towards new migrants was widely criticised. The ideological foundation for that policy was, arguably, the country’s experience of integrating millions of ethnic German expellees and refugees from Central and Eastern Europe in the aftermath of the Second World War.

Description: food supply; environmental aspects; sustainable agriculture; nutrition policy

Description: Strains with a yeast-like appearance were frequently collected in two surveys on the biodiversity of fungi in Germany, either associated with necroses in wood of Prunus trees in orchards in Saxony, Lower Saxony and Baden-Württemberg or captured in spore traps mounted on grapevine shoots in a vineyard in Rhineland-Palatinate. The morphology of the strains was reminiscent of the genus Collophorina: all strains produced aseptate conidia on integrated conidiogenous cells directly on hyphae, on discrete phialides, adelophialides and by microcyclic conidiation, while in some strains additionally endoconidia or conidia in conidiomata were observed. Blastn searches with the ITS region placed the strains in the Leotiomycetes close to Collophorina spp. Analyses based on morphological and multi-locus sequence data (LSU, ITS, EF-1α, GAPDH) revealed that the 152 isolates from wood of Prunus spp. belong to five species including C. paarla, C. africana and three new species. A further ten isolates from spore traps belonged to seven new species, of which one was isolated from Prunus wood as well. However, a comparison with both LSU and ITS sequence data of these collophorina-like species with reference sequences from further Leotiomycetes revealed the genus Collophorina to be polyphyletic and the strains to pertain to several genera within the Phacidiales. Collophorina paarla and C. euphorbiae are transferred to the newly erected genera Pallidophorina and Ramoconidiophora, respectively. The new genera Capturomyces, Variabilispora and Vexillomyces are erected to accommodate five new species isolated from spore traps. In total nine species were recognised as new to science and described as Collophorina badensis, C. germanica, C. neorubra, Capturomyces funiculosus, Ca. luteus, Tympanis inflata, Variabilispora flava, Vexillomyces palatinus and V. verruculosus.

Description: Ambrosia beetles farm specialised fungi in sapwood tunnels and use pocket-like organs called mycangia to carry propagules of the fungal cultivars. Ambrosia fungi selectively grow in mycangia, which is central to the symbiosis, but the history of coevolution between fungal cultivars and mycangia is poorly understood. The fungal family Ceratocystidaceae previously included three ambrosial genera (Ambrosiella, Meredithiella, and Phialophoropsis), each farmed by one of three distantly related tribes of ambrosia beetles with unique and relatively large mycangium types. Studies on the phylogenetic relationships and evolutionary histories of these three genera were expanded with the previously unstudied ambrosia fungi associated with a fourth mycangium type, that of the tribe Scolytoplatypodini. Using ITS rDNA barcoding and a concatenated dataset of six loci (28S rDNA, 18S rDNA, tef1-α, tub, mcm7, and rpl1), a comprehensive phylogeny of the family Ceratocystidaceae was developed, including Inodoromyces interjectus gen. & sp. nov., a non-ambrosial species that is closely related to the family. Three minor morphological variants of the pronotal disk mycangium of the Scolytoplatypodini were associated with ambrosia fungi in three respective clades of Ceratocystidaceae: Wolfgangiella gen. nov., Toshionella gen. nov., and Ambrosiella remansi sp. nov. Closely-related species that are not symbionts of ambrosia beetles are accommodated by Catunica adiposa gen. & comb. nov. and Solaloca norvegica gen. & comb. nov. The divergent morphology of the ambrosial genera and their phylogenetic placement among non-ambrosial genera suggest three domestication events in the Ceratocystidaceae. Estimated divergence dates for the ambrosia fungi and mycangia suggest that Scolytoplatypodini mycangia may have been the first to acquire Ceratocystidaceae symbionts and other ambrosial fungal genera emerged shortly after the evolution of new mycangium types. There is no evidence of reversion to a non-ambrosial lifestyle in the mycangial symbionts.

Description: On April 6, 2009, an Mw 6.3 earthquake struck the town of L’Aquila in the Abruzzo region in central Italy. It was followed by a long seismic crisis with other four events with Mw between 5.1 and 5.6. Seismological and geological data point out an upper crust extensional stress field with an average WSW-ENE tensional axis. In the course of the seismic sequence, two distinct en échelon fault sources were activated: first, the SW-dipping Paganica normal fault, which is associated with the Mw 6.3 event; and, subsequently, the southern part of the WSW-dipping Gorzano normal fault.Co-seismic ground deformation (open fissures, en échelon cracks and shear planes with centimetric downthrows) was surveyed for ~ 13 km along the Paganica fault. The integration of the information from this last Italian earthquake with the previous seismotectonic background has allowed us to further detail the 3-D shape and the size of some of the individual seismogenic sources of the Apennine active extensional belt.

Description: Published

Description: 1-17

Description: 2T. Tettonica attiva

Description: restricted

Description: The Principal Cordillera of Central Chile is characterized by two belts of different ages and lithologies: (i) an eastern Mesozoic belt, consisting of limestone- and gypsum-rich sedimentary rocks at the border between Central Chile and Argentina, where the active volcanic arc occurs; and (ii) a western belt of Cenozoic age containing basaltic to andesitic volcanic and volcanoclastic sequences. This distinctive geological setting controls water chemistry of cold and thermal springs in the region, which are fed by meteoric water that circulates through deep regional structures. In the western sector of Principal Cordillera, water–rock interaction processes produce lowTDS, slightly alkaline HCO3 − dominatedwaters, although dissolution of underlyingMesozoic evaporitic rocks occasionally causes SO4 2− and Cl− enrichments. In this area, few Na+–HCO3 − and Na+–SO4 2− waters occurred, being likely produced by a Ca2+–Na+ exchange during water–rock interactions. Differently, the chemical features of Ca2+–Cl−waterswas likely related to an albitization–chloritization process affecting basaltic to andesitic rocks outcropping in this area. Addition of Na+–Cl− brines uprising from the eastern sector through the westverging thrust faults cannot be excluded, as suggested by the occurrence of mantle He (~19%) in dissolved gases. In contrast, in the eastern sector of the study region, mainly characterized by the occurrence of evaporitic sequences and relatively high heat flow,mature Na+–Cl− waters were recognized, the latter being likely related to promising geothermal reservoirs, as supported by the chemical composition of the associated bubbling and fumarolic gases. Their relatively low3He/4He ratios (up to 3.9 Ra)measured in the fumaroles on this area evidenced a significant crustal contamination by radiogenic 4He. The latter was likely due to (i) degassing from 4He-rich magma batches residing in the crust, and/or (ii) addition of fluids interacting with sedimentary rocks. This interpretation is consistent with the measured δ13C-CO2 values (from−13.2 to−5.72‰vs. V-PDB) and the CO2/3He ratios (up to 14.6 × 1010), which suggest that CO2 mostly originates from the limestone-rich basement and recycling of subducted sediments,with an important addition of sedimentary (organic-derived) carbon,whereas mantle degassing contributes at a minor extent. According to geothermometric estimations based on the Na+, K+, Mg2+ and Ca2+ contents, the mature Na+–Cl− rich waters approached a chemical equilibrium with calcite, dolomite, anhydrite, fluorite, albite, K-feldspar and Ca- andMg-saponites at a broad range of temperatures (up to ~300 °C) In the associated gas phase, equilibria of chemical reactions characterized by slowkinetics (e.g. sabatier reaction) suggested significant contributions from hot and oxidizing magmatic gases. This hypothesis is consistent with the δ13C-CO2, Rc/Ra, CO2/3He values of the fumarolic gases. Accordingly, the isotopic signatures of the fumarolic steam is similar to that of fluids discharged from the summit craters of the two active volcanoes in the study area (Tupungatito and Planchón–Peteroa). These results encourage the development of further geochemical and geophysical surveys aimed to provide an exhaustive evaluation of the geothermal potential of these volcanic–hydrothermal systems.

Description: Published

Description: 97-113

Description: 1V. Storia e struttura dei sistemi vulcanici

Description: JCR Journal

Description: restricted

Description: Historical and recent seismicity records and available source mechanisms in eastern-central Italy (Marche–Adriatic region), in mainland-southern Sicily and in the Tyrrhenian offshore of northern Sicily show com- parable deformation patterns. Seismotectonic consider- ations indicate that each of the three areas represents a broad seismogenic province of relatively homogeneous deformation. On the basis of the historical earthquake catalogue, the parameters of the Gutenberg–Richter dis- tribution have been calculated by means of a Monte Carlo simulation method. The average moment tensors have been computed from focal mechanism data and the strain rate and velocity tensors evaluated by means of Kostrov’s (in Izv Acad Sci USSR Phys Solid Earth 1:23–44, 1974) relation, which also considers the shape and size of the seismogenic volume. The uncertainties have been system- atically incorporated. The results show that the three seis- motectonic provinces are all undergoing shortening at seismic rates (*0.3 mm/year in the WSW–ENE direction in the eastern Marche–Adriatic region, *0.1 mm/year in the N–S direction in mainland-southern Sicily and *0.2 mm/year in the NW–SE direction in the Southern Tyrrhenian zone). The motion pattern in the Marche– Adriatic and in the Sicilian provinces suggests that these areas undergo active crust-scale deformation along reverse shear zones, in agreement with recent horizontal GPS motion model and other independent evidence.

Description: Published

Description: 2T. Tettonica attiva

Description: JCR Journal

Description: restricted

Description: We compare the seismogenic role played by two crustal-scale reverse-type shear zones located at the outer border of the Apennine- Maghrebian fold-and-thrust belt system: the westward-dipping Adriatic Basal Thrust (ABT) in eastern-central Italy and the northward-dipping Sicilian Basal Thrust (SBT) in southern Sicily. The epicentral and hypocentral distributions and, whenever possible, the kinematics of a merged dataset of pre-instrumental (1600 to 1900), early instrumental (1901 to 1980) and instrumental (1981 to 2005) earthquakes with moment magnitude ≥4.5 sited within the surface areas above the ABT and the SBT depth-contour lines (0-30 km) are analysed. They are both first-order crustal-scale seismogenic structures which strongly control reverse, reverse-oblique and strike-slip seismic activity. Relatively deep (10-to-30 km) seismicity occurring in the foothills region and in main- land Sicily may be associated with brittle shearing of the middle and lower crust ABT and SBT thrusts segments, whereas the shallow seis- micity (〈10 km) close to the ABT and SBT surface tip line is associated with reverse, oblique and strike-slip shearing of the two upper crust thrust segments and their frontal and lateral splays. Despite that the seismic activity within the two studied areas, and especially in Sicily, is commonly considered minor, several highly damaging earthquakes have struck both areas. In the last four centuries, there is knowledge of 37 events with magnitude 〉5.0 in the Marche-Coastal Adriatic region, among which are the 1741 Fabrianese (Maw 6.08) and 1799 Camerino (Maw 5.93) events, and of 10 events with magnitude 〉5.0 in southern and mainland Sicily, including the 1818 Catanese (Maw 6.00) and 1968 Valle del Belice (Maw 6.12) events. Based on the integration of tectonic and seismological con- straints, the boundaries of two seismogenic compressional provinces located above the ABT and the SBT are defined and the associated values of yearly energy release per unit area evaluated. Similar val- ues are obtained for the ABT (~8E+14 erg/y/km2) and for the SBT (~4E+14 erg/y/km2). The recognition of close geometric, kinematic and seismotectonic similarities between the two compressional provinces, further supported by a comparable level of long-term seis- mic activity, has evident implications both for regional tectonic reconstructions and for seismic hazard assessment purposes.

Description: Published

Description: 2T. Tettonica attiva

Description: N/A or not JCR

Description: open

Description: This paper proposes a new seismogenic interpretation of mainland and central-southern Sicily, based on an integrated structural–kinematic–seismological approach. Through analysis of available structural and geophysical data, the tectonic setting, the major kinematic units and the crust geometry of the Sicilian southward-verging fold-and-thrust belt system are schematized in sections and in map form. The depth-contour lines of the outermost basal thrust plane, which dates back to Plio-Pleistocene times with some evidence of Holocene activity, are reconstructed. This plane, here named Sicilian Basal Thrust (SBT), emerges along the southward convex Sciacca–Gela–Catania front and reaches the base of the crust at a depth of about 30 km beneath northern Sicily. Additionally, an important regional upper crust splay, with the same arched shape, has been identified some kilometres northward. In order to detect any possible indication of seismogenic activity linked to ongoing deformation of the SBT and its splay, we analyzed the distribution and kinematics of the instrumental seismicity in the period between 1981 and 2006. Particular attention was given to the background seismicity (Ml up to 4.6) located beneath the sedimentary cover at Mt. Etna, as it allows individuating a northward deepening seismogenic volume undergoing an average N–S compression, which corresponds well with the SBT geometry in section view. A merged dataset of all the known major historical and instrumental events (moment magnitude ≥ 4.5) that occurred above the SBT 0-to-30 km depth-contour lines from 217 B.C. to 2006 was compiled and analyzed. Based on information from instrumental data and/or on speculations on the shape and extent of the historical earthquake macroseismic fields, two major ranges of hypocentral depths have been schematically identified within the merged dataset: an upper crust range (in average b~ 10 km) and a mid-to-lower crust range. Focal mechanisms available in the literature show prevailing reverse and reverse-oblique kinematics, compatible with a nearly average N–S shortening and with some field evidence of active fold-and- thrust deformation at the SBT front and along its inner splay. Several moderate earthquakes (nearly 40 in the last 400 years with moment magnitude ranging from 4.5 to 5.5) and a few more energetic events with moment magnitude up to ~ 6.0, such as the Mineo 1624, the Belice 1968 and the Catania 1818 events, can be attributed to an ongoing activity of the SBT. In previous studies, these events had been often attributed to isolated N–S strike-slip sources located within the Hyblean-Pelagian foreland, while all the interposed areas had been considered aseismic, as well as the SBT had been considered inactive. The identification in the SBT of a unique regional-scale seismogenic structure capable to connect the active deformation and the seismic activity of the western, central and eastern areas of mainland Sicily and those of central-southern Sicily evidently has strong implications in terms of seismic hazard assessment. In fact, it allows the definition of a new homogeneous compressional seismotectonic province, which extends between the SBT surface front line and the surface projection of the 25 km SBT depth-contour line. A subdivision in two sub-provinces, a shallow one above the 0–10 km SBT segment and a deep one above the 10-to-25 km SBT segment, is also considered and the energy released of the associate earthquakes evaluated. To conclude, the proposed model is discussed in comparison with other models from the literature and some important open problems are put forwards.

Description: Published

Description: 145 – 167

Description: 2T. Tettonica attiva

Description: JCR Journal

Description: restricted