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The Carpathian-Pannonian Region (CPR) hosted some of the largest silicic volcanic eruptions in Europe during the Early and Middle Miocene, contemporaneously with major lithospheric thinning of the Pannonian Basin. This was recorded as an ignimbrite flare-up event from approximately 18.1–14.4 Ma. To gain in-depth perspectives on the eruption chronology, tephrostratigraphy, and petrogenesis at the onset of CPR silicic volcanism, we applied a multi-proxy approach to Lower Miocene rhyolitic ignimbrites and pyroclastic fall deposits from the northern CPR to the Dinaride Lake System. High-precision zircon U-Pb geochronology distinguished two Lower Miocene groups of volcaniclastic rocks at ∼ 18.1 Ma and ∼ 17.3 Ma. Based on combined tephrostratigraphic signatures we propose that the ∼ 18.1 Ma Kalnik and ∼ 17.3 Ma Eger eruptions produced widespread (intermediate to) large caldera-forming massive rhyolitic ignimbrites, deposited across northern and southwestern regions of the CPR. Due to easterly winds that carried volcanic ash hundreds of kilometers to the southwest, Eger eruption products also reached distal intra-montane Dinaride lacustrine basins, recorded as pyroclastic fall deposits. Heterogeneous major and trace elemental compositions of ∼ 18.1 Ma volcanic glass shards suggest that the Kalnik eruption was sourced from complex silicic magmatic systems, with simultaneous tapping of two discrete melt bodies during the eruption. The homogeneous geochemical composition of ∼ 17.3 Ma glasses is distinct from the older glasses. Integrated zircon and bulk glass Nd-Hf isotope compositions have a positive correlation, defining a regional mantle array, and are more radiogenic in the younger phase of volcanism. The recorded systematic isotopic change, moving from older more crustal signatures to younger more juvenile compositions, imply that during the period of lithospheric thinning of the Pannonian Basin the region underwent more complex variations in the interaction between metasomatized lithospheric mantle-derived magmas and various crustal components than previously recognized.

In remote sensing of landslide investigation, the interpretation of optical image is the main method at present. However, when a disaster occurs, it is very difficult to obtain images without cloud coverage. For example, Typhoon Lubi in August 2021 and Typhoon Nissa in 2022 caused many landslides and road interruptions. However, due to the cover of clouds and fog, it was impossible to obtain satellite images in time to judge the scale of the disaster. Unmanned vehicles are also affected by weather factors, which greatly increases the risk of flight. Therefore, it is extremely necessary to develop disaster identification methods that are not affected by weather.In this study, the long electromagnetic waves of synthetic aperture radar (SAR) are not affected by cloud and fog to develop a landslide detection model for radar images. The reference range of the location and scale of the landslide can be obtained under bad weather conditions to make up for the weather limitations when evaluating the scope of the disaster with optical images.In this study, the NDSI&RVID method is used as the index for the identification and interpretation of the landslide area, and the analysis and discussion of the landslide area is carried out in combination with multi-time series and different orbital data. The effect of landslide identification is improved by three methods: single-sequence identification and interpretation stacking, multi-time-series index stacking, and multi-time-series image stacking. Among them, better interpretation results can be achieved by stacking multiple time-series images. It is recommended to use the number of 4 images before the disaster and 1 image after the disaster for data interpretation. Although the image pixel classification effect still needs to be improved, the identification rate for landslides of more than 10 hectares can reach more than 90%. In the absence of optical images, it has considerable reference value.

The deep-seated landslides often caused severe hazard due to the large area and landslide mass associated with the landslide movement. Thus, monitoring the landslide movement is an important task for landslide hazard management. The Microelectromechanical Systems (MEMS) technique developed rapidly in recent years provides the ability of low-cost sensors and easy installation for monitoring of the landslide movement in field. Typically, the landslide movement monitoring using MEMS is based on the tilt angle determined from the measured ground acceleration variations in three directions, and being subjected to the signal noise. We adopt Moving Window Fast Fourier Transform and other seismic wave analysis in this study to improve resolution of the seismic signals and achieve a sound detection of deep-seated landslide movement. The MEMS was installed at the Lantai deep-seated landslide study area, which measured the ground accelerations mid-slope of the landslide. The seismic signals recorded for eleven earthquake events and three heavy rainfall events are selected for analysis. It was found that the signal frequency can be separated from the system responses and related to the landslide movement. Validations were conducted by comparing the analysis results to the field monitoring data of in-place inclinometer and borehole extensometer while available. It is suggested that the landslide movement can be identified with seismic signal at approximately 17 Hz, and the results are consistent for both earthquake-induced and rainfall-induced events.

Organic semiconducting polymers exhibited promising photocatalytic behavior for hydrogen (H2) evolution, especially when prepared in the form of polymer dots (Pdots). However, the Pdot structures were formed using common nonconjugated amphiphilic polymers, which have a negative effect on charge transfer between photocatalysts and reactants and are unable to participate in the photocatalytic reaction. This study presents a new strategy for constructing binary Pdot photocatalysts by replacing the nonconjugated amphiphilic polymer typically employed in the preparation of polymer nanoparticles (Pdots) with a low-molecular-weight conjugated polyelectrolyte. The as-prepared polyelectrolyte/hydrophobic polymer-based binary Pdots truly enhance the electron transfer between the Pt cocatalyst and the polymer photocatalyst with good water dispersibility. Moreover, unlike the nonconjugated amphiphilic polymer, the photophysics and mechanism of this photocatalytic system through time-correlated single-photon counting (TCSPC) and transient absorption (TA) measurements confirmed the Forster resonance energy transfer (FRET) between the polyelectrolyte as a donor and the hydrophobic polymer as an acceptor. As a result, the designated binary Pdot photocatalysts significantly enhanced the hydrogen evolution rate (HER) of 43 900 μmol g-1 h-1 (63.5 μmol h-1, at 420 nm) for PTTPA/PFTBTA Pdots under visible-light irradiation.

In this study, new geological, geochronological, geochemical, and Nd–Hf isotopic data are presented for the Melange Zone within the Zavkhan terrane, Mongolia, and the terrane structure, early Neoproterozoic continental crust growth, and microcontinent formation in the north–central part of the Central Asian Orogenic Belt (CAOB) are discussed. The Melange Zone separates high-grade complexes of the northwestern part of the Zavkhan terrane and unmetamorphosed Neoproterozoic Zavkhan Formation covered by Cryogenian–Cambrian shelf deposits of the southwestern part. Zone consist of a lower-grade association of basalts, basaltic andesites, rarely felsic volcanic rocks, trondhjemites of the Kharuul Massif and variably metamorphosed from greenschist- to upper amphibolite-facies, and high-grade metamorphic rocks including quartzite–gneisses, hornblende schists, and amphibolites with relics of eclogite and blueschist-facies metamorphism assemblages. Emplacement of trondhjemites and gabbro dykes of the Kharuul Massif occurred at about 960–930 Ma. Geochemical, Nd whole-rock, and Hf-in-zircon isotopic data indicate an oceanic island arc setting for the lower-grade association. LA-ICP-MS dating and Hf-in-zircon data for detrital zircons from the quartzite–gneisses of the Melange Zone indicate that the sources comprise Palaeoproterozoic (ca. 2.02 and 2.48 Ga), Neoarchean (ca. 2.59 and 2.67 Ga), and Mesoarchean (ca. 2.8 and 3.0 Ga) magmatic and metamorphic crustal rocks as well as 2.6–2.5 Ga juvenile complexes. High-grade amphibolites show geochemical similarity to continental arc and within-plate basalts, and were formed from enriched mantle sources. Obtained combined with published data demonstrate that the Zavkhan terrane represents composite terrane composed of ca. 960–930 Ma island arc complex, and ca. 860–800 Ma active continental margin complexes in the north and reworked at ca. 800–720 Ma early Precambrian continental crust in the south, which are separated by a Melange Zone. We speculate that formation of the latest Mesoproterozoic–early Neoproterozoic island arc and active continental margin complexes in the north–central CAOB could be related to the assembly of the Rodinia supercontinent at ca. 1.1–1.0 Ga, which initiated subduction in Mirovian Ocean and led to the development of accretionary orogens around supercontinent margins.

The climactic Los Chocoyos (LCY) eruption from Atitlán caldera (Guatemala) is a key chronostratigraphic marker for the Quaternary period given the extensive distribution of its deposits that reached both the Pacific and Atlantic Oceans. Despite LCY tephra being an important marker horizon, a radioisotopic age for this eruption has remained elusive. Using zircon (U–Th)/He geochronology, we present the first radioisotopically determined eruption age for the LCY of 75 ± 2 ka. Additionally, the youngest zircon crystallization 238U–230Th rim ages in their respective samples constrain eruption age maxima for two other tephra units that erupted from Atitlán caldera, W‐Fall (130 +16/−14 ka) and I‐Fall eruptions (56 +8.2/−7.7 ka), which under‐ and overlie LCY tephra, respectively. Moreover, rim and interior zircon dating and glass chemistry suggest that before eruption silicic magma was stored for >80 kyr, with magma accumulation peaking within ca. 35 kyr before the LCY eruption during which the system may have developed into a vertically zoned magma chamber. Based on an updated distribution of LCY pyroclastic deposits, a new conservatively estimated volume of ~1220 ± 150 km3 is obtained (volcanic explosivity index VEI > 8), which confirms the LCY eruption as the first‐ever recognized supereruption in Central America., Deutsche Forschungsgemeinschaft SCH 2521/6‐1

This work presents new U–Pb ID-TIMS geochronological data obtained for the rocks of the metagabbro–diorite–tonalite complex of the Olondo fragment of the Tokko–Khani greenstone belt of the Aldan Shield, Siberian Craton. Wide development of ultramafic and mafic volcanics associated with felsic volcanics has been recognized only within this fragment. It was established that the protoliths of metagabbro–diorite and quartz metadiorite intruding metavolcanic and metasedimentary rocks were crystallized at 3002 ± 5 and 3005 ± 7 Ma, respectively. The obtained age estimates determine the upper age boundary of the formation of the Olondo supracrustal rocks (3012–2997 Ma). The Nd model ages of the Olondo metaandesites and metadacites are close to 3.0 Ga, which, to the first approximation, determines the lower age boundary of their formation. Thus, the sedimentary–volcanogenic sequence of the Olondo fragment are about 3.0 Ga old, and their formation, including superimposed structural and metamorphic transformations, occurred within a short period (a few million years).

Mts. Kalnik and Požeška gora volcaniclastic sequences hold valuable information concerning the Miocene syn-rift evolution of the North Croatian Basin, and the evolution of the Carpathian–Pannonian Region and the Central Paratethys. We present volcanological, high-precision geochronological, and compositional data of volcanic glass to constrain their tephrochronology, magmatic provenance, and timing of the initial Central Paratethys flooding of the North Croatian Basin. Based on CA-ID-TIMS U–Pb zircon ages (18.060 ± 0.023 Ma for Mt. Kalnik and 15.345 ± 0.020 Ma for Mt. Požeška gora) and coeval 40Ar/39Ar sanidine ages (18.14 ± 0.38 Ma and 18.25 ± 0.38 Ma for Mt. Kalnik and 15.34 ± 0.32 Ma and 15.43 ± 0.32 Ma for Mt. Požeška gora), Mt. Kalnik rhyolitic massive ignimbrites and Mt. Požeška gora rhyolitic primary volcaniclastic turbidites are coeval with Carpathian–Pannonian Region Miocene post-collisional silicic volcanism, which was caused by lithospheric thinning of the Pannonian Basin. Their affiliation to Carpathian–Pannonian Region magmatic activity is supported by their subduction-related geochemical signatures. Although Mts. Kalnik and Požeška gora volcaniclastics are coeval with the Bükkalja Volcanic Field Csv-2 rhyolitic ignimbrites, North Alpine Foreland Basin, Styrian Basin, Vienna Basin, and Dinaride Lake System bentonites and volcaniclastic deposits, reliable tephrochronological interpretations based on comparison of volcanic glass geochemical composition are not possible due to a lack of data and/or methodological discrepancies. Our new high-precision geochronology data prove that the initial Middle Miocene (Badenian) marine flooding of parts of the North Croatian Basin occurred at least ~ 0.35 Ma (during the NN4 Zone) before the generally accepted ~ 15 Ma maximum flooding age at the basin scale, calibrating the timing of the onset of the widespread “mid-Langhian” Central Paratethys flooding.

We have developed high-performance photorefractive (PR) materials containing ternary composites of 2-ethylhexyl plasticized poly(triarylamine) (PTAA), a chromophore, and a photosensitizer. PTAAs containing carbazole or fluorene in a main chain and 2-ethylhexyl in a side chain are synthesized via palladium-complex catalyzed polyamination. The spectroscopic, thermal, and hole-transport properties of these polymers are analysed. The carbazole-containing polymer shows good compatibility with chromophores, affording the high chromophore loading of polymer/chromophore = 70/30 wt%. This polymer can be utlilised in PR devices as a host material without any additional plasticizer. The PR performance of a polymer/chromophre/sensitizer (69/30/1 wt%) composite was evaluated using an optical four-wave mixing technique (FWM) to determine the change in refractive index Δn and the average-response time constant τ. This composite exhibits results comparable to the inorganic crystals BSO or SPS when the optical sensitivity is maximized at 15.8 cm3 kJ−1, with Δn = 5.3 × 10−4 and τ = 2 milliseconds under a pump-laser intensity of 149 mW cm−2. This is one of the highest values obtained for an organic PR composite with a pump laser operating at 633 nm.

We developed high-performance lithium ion batteries (LIBs) based on submicron-sized recycled silicon and conjugated polymer binders. The polymer binders were synthesized by palladium-catalyzed dire...

Acigol volcanic complex is a bimodal volcanic field located at the western margin of the Neogene–Quaternary Cappadocian volcanic province in Central Anatolia (Turkey). Its most voluminous eruptions are preserved as a pair of widespread tuffs known as Lower Acigol Tuff (LAT) and Upper Acigol Tuff (UAT). Both are nearly aphyric high-silica rhyolites that are compositionally identical; they can be distinguished, however, by the presence of obsidian lithics in UAT and the absence thereof in LAT. Here, we report the discovery of medial deposits of these tuffs at ~ 60–65 km distance from their source, and re-estimate the volume for LAT in the range of 21.4–26.7 km3 (similar constraints are lacking for UAT, but a subequal volume is assumed). Development of paleosol between LAT and UAT provides evidence for a hiatus between both events which is further supported by radiometric dating using combined U–Th and (U–Th)/He zircon geochronology. The revised age for LAT based on sequence modeling of U–Th zircon crystallization and (U–Th)/He zircon eruption ages is 190 ± 11 ka, whereas new and published (U–Th)/He zircon ages indicate eruption of UAT at 164 ± 4 ka (uncertainties generally stated at 1σ). The compositional similarity between both eruptions previously known from whole-rock analyses also extends to glass major, minor, and trace element compositions. Moreover, U–Th zircon crystallization ages are also indistinguishable between LAT and UAT in proximal and medial locations. U–Pb zircon ages for crystals in secular equilibrium indicate a provenance from Cretaceous granitic basement and Miocene volcanic overburden typical for Cappadocia, and such xenocrysts appear to be slightly more common in LAT compared to UAT. The compositional similarity between LAT and UAT along with the apparent recycling of zircon from the non-erupted LAT magma during the UAT event indicates sequential tapping of rhyolite melt from a magma system that maintained thermal and compositional uniformity over a protracted time interval. This can be explained by rhyolite melt extraction from a thermally buffered crystal mush that remained viable to produce voluminous high-silica eruptions for few 10s of ka. The subsequent migration of eruptive activity in the Acigol volcanic complex from east to west also led to a change in magma chemistry and triggered a new pulse of zircon crystallization, indicating abandonment of the previous magmatic focus, and a shift of magma input to a new location. The identification of sizable medial deposits of LAT and UAT implies that both tephra units are potentially useful marker horizons for marine isotope stage (MIS) 6 sedimentary sequences in and around Anatolia. The recent discovery of UAT in a Black Sea sediment core supports this view.

Interactions of hydrous fluid and melt with dry mantle rocks are known to result in metasomatic alteration of the lithospheric mantle. Here we investigate such interactions that occurred beneath the Hangay Dome, Mongolia, in 22 mantle xenoliths, which were recovered from Cenozoic basalts at the Tsagan, Zala, Horgo, and Shavaryn-Tsaram localities near the village of Tariat. The xenoliths are medium- to coarse-grained spinel lherzolites that exhibit variable degrees of reaction with silicate melt and fluid (indicated by their Fe- and LREE-enrichment and the presence of secondary clinopyroxene, amphibole, phlogopite, apatite, and sulfide). According to their normalized REE patterns and microstructures, the spinel lherzolites were divided into three groups. Group 1 lherzolites contain LREE-depleted clinopyroxene and whole-rock compositions, exhibit a greater number of preserved deformation textures, and are the least affected by metasomatism. These lherzolites are interpreted to represent the sub-continental lithosphere before the rejuvenation processes that occurred during the Cenozoic. Group 3 lherzolites are characterized by partial annealing of pre-existing textures, and LREE-enrichment in clinopyroxenes and whole-rock compositions compared to Group 1 lherzolites. Group 3 lherzolites are interpreted to be the result of the interaction of depleted lithospheric mantle with a basaltic melt during the Cenozoic. The lack of correlation between the intensity of metasomatism, the degree of annealing, and the calculated temperatures of the lherzolites suggests that the Cenozoic basaltic melt percolation postdates the static recrystallization. Group 2 lherzolites exhibit characteristics from both Groups 1 and 3. Numerical modelling of the interaction between depleted lherzolites and basaltic melts evidences that: (i) a single initial liquid may fractionate to produce a range of element patterns: the observed spectrum of REE compositions of the Tariat lherzolites cannot have resulted from simple mixing of basaltic melt with a depleted mantle rocks; instead, it can be explained by chromatographic fractionation during reactive porous melt flow; (ii) highly fractionated element patterns are derived from conventional initial melt compositions and do not imply the existence of exotic melts; and (iii) strong element fractionation can be produced along short distances even at the thin section and mineral scale; this opposes the view that long percolation distances are required to produce significant chromatographic effects: the clinopyroxene core-rim disequilibrium demonstrates that REE variations in clinopyroxene rims were acquired in response to interactions with a more evolved REE-rich melt.

The Paleo-Tethyan orogenic record is well preserved in the Sanjiang area of SW China. However, ophiolites are commonly dismembered in orogenic belt, and complete ophiolite sequences are rare in the Sanjiang area. In this manuscript, we present a newly discovered ophiolite in the Yakou-Banpo area of the southern Lancangjiang belt in the Sanjiang area, SW China. The ophiolite displays a complete Penrose-type ophiolite sequence, composed of serpentinized peridotite, isotropic and cumulate gabbros, massive and pillow basalts, and plagiogranite. Whole-rock geochemical data indicate that these rocks were formed in an oceanic ridge setting, and they show depletions in Nb, Ta and Ti, and enrichment in Pb, suggesting a supra-subduction zone affinity. Furthermore, positive Ɛ Nd (t) (+4.5 to +6.7) and zircon Ɛ Hf (t) values (+12.4 to +14.3), as well as mantle-like δ 18 O values (~5.5‰), suggest that these rocks were derived from a long-term depleted mantle source. SHRIMP zircon U Pb dating yield weighted mean ages of 305 ± 3 Ma, 310 ± 2 Ma, and 313 ± 6 Ma. Hence, the Yakou-Banpo ophiolite belt formed during the Late Carboniferous (313–305 Ma) and records the existence of a mature ocean basin. We propose that an arc – back-arc system developed in the Sanjiang Paleo-Tethyan orogenic belt of SW China during the Late Carboniferous.

The eclogites of the North Muya complex (Eastern Siberia) are located within the Early Neoproterozoic metasedimentary and felsic rocks of the Baikal-Muya Fold Belt (BMFB). The eclogites show subduction-related affinity, with large-ion lithophile (LILE) and light rare-earth element (LREE) enrichment and high field-strength element (HFSE) depletion signatures, similar to the exposed plutonic and volcanic rocks of the Early Neoproterozoic (Early Baikalian) subduction setting in the BMFB. Coupled Nd (eNd(T) of +6 to −1.4) and Sr (87Sr/86Sr ratio of 0.705–0.708), along with key trace-element indicators, imply progressive crustal recycling (up to 5–10%) from the Early Precambrian continental rocks to a depleted mantle source or equivalent crustal contribution via intracrustal contamination. Mineral δ18O data (+3.9 − +11.5) indicate that the contaminant or recycled crustal substrate might be represented by rocks altered at both low and high-temperature, or result from variable fluid-rock interaction in the subduction channel. Pseudosection modelling of eclogites, coupled with zircon U Pb geochronology (~630 Ma) suggest that the Ediacarian high-pressure metamorphic event for different rocks shared a maximum depth corresponding to 2.5–2.7 GPa with variable temperature range (560–760 °C), reflecting their potential relation to distinct slices of the subducted crust. The estimated metamorphic conditions for both the burial and exhumation of rocks indicate a continental subduction setting, but with a relatively cold geotherm (~20–25 °C/kbar). These conditions resulted from the continental subduction of the Baikal-Muya composite structure beneath the relatively thin and immature overlying arc lithosphere of southern Siberia. Some carbonate-bearing eclogites and garnet-pyroxene rocks, metamorphosed under T below 700 °C and a minimum P up to 1.4 GPa, exhibit LREE-enriched patterns and low eNd(T) values of −7 to −16. These rocks have Paleoproterozoic to Archean model ages and may support the existence of a Paleoproterozoic or older lithosphere in the Baikal-Muya Fold Belt, but their subduction history and origin remain uncertain due to geochemical and isotopic signatures probably overprinted by carbonate metasomatism.

The results of U–Th–Pb geochronological (LA-ICP-MS) and Hf isotope (LA-MC-ICP-MS) studies of detrital zircons from sandstones and also the results of Nd isotope studies of whole rocks from the tillite-bearing Maikhan-Uul Formation of the Tsagaan-Olom Group of the shelf cover of the southeastern part of the Dzabkhan terrane of the Central Asian Orogenic Belt are considered. The obtained data made it possible to establish that the sources of sandstones of the Maikhan-Uul Formation of the Tsagaan-Olom Group were rocks of the Neoproterozoic and the Early Precambrian complexes with Archean and Paleoproterozoic Hf and Nd model ages, as well as Neoproterozoic igneous rocks formed from both juvenile and crustal sources. The age of the sandstones of the Maikhan-Uul Formation is in the range of ca. 720–660 Ma. It is shown that a large-scale manifestation of convergence processes with the formation of the juvenile crust and the reworking of the ancient continental crust is established in the structures of the central segment of the Central Asian Orogenic Belt in the Early Neoproterozoic (ca. 960–780 Ma). Most likely, these processes reflect the development of the global subduction system in the paleooceanic region of the Rodinia supercontinent margins.

U-Pb-Hf isotopes of zircons from the granitic intrusive rocks in the Iwakuni area of Southwest Japan are determined by LA-ICP-MS analysis. The Gamano Granodiorite belonging to the Older Ryoke Granites of the Ryoke Belt yielded U-Pb mean age of 92.3 ± 2.6 Ma (MSWD = 1.8). The Namera Granite belonging to the Younger Ryoke Granites of the Ryoke Belt yielded U-Pb mean age of 106.3 ± 1.6 Ma (MSWD = 2.3). The Shimokuhara Granite belonging to the Hiroshima Granites of the San-yo Belt yielded U-Pb mean age of 103.8 ± 1.5 Ma (MSWD = 0.32). A granite porphyry sample taken from about 15 m thick dike discordantly intruded into pelitic schist of the Ryoke metamorphic rocks yielded U-Pb mean age of 92.5 ± 1.6 Ma (MSWD = 0.63). Hf isotope data, obtained from the same dated zircon grains, show initial 176Hf/177Hf isotopic ratios referred to as “eHf(t)” generally ranging between–4.8 and +1.1 except an anomalously low value (–15.0) from an inherited core. The eHf(t) values, calculated with average crustal 176Lu/177Hf ratio of 0.015, correspond to Hf isotope crustal model ages between 1474 to 1087 Ma (Mesoproterozoic). The Gamano Graodiorite has long been regarded to be a syn-tectonic intrusion, but the zircon ages and eHf(t) values are similar to those of the post-tectonic granite porphyry dike. The results of this study together with available U-Pb zircon ages of granitic rocks in the Iwakuni area reported elsewhere reveal that the order of emplacement indicated by the U-Pb zircon ages are much discrepant with the traditional classification, the Older Ryoke, the Younger Ryoke. It is better to refrain from the use of “Older” and “Younger” for the collective names of the granitic intrusive bodies.

A comparison of the lithological-geochemical parameters for the deposits of the Dalnetaiga series of the Bodaibo synclinorium (the Buzhuikhta and Khomolkho suites) and the Olokit structural-formation zone (the Itykit and Ondok suites), hosting polymetallic deposits (Kholodnin, Ioko-Rybach’e), along with the obtained geochronological LA-ICP-MS U–Pb age estimates of the Ondok suite (~600 Ma), indicates their similar stratigraphic position in the Neoproterozoic in Southern Siberia. At the first stage of formation of polymetallic and gold-ore objects, the siderochalcophylic trend is considered to have appeared synchronously in the two structural zones, which could have been caused by the hydrothermal activity in the backarc basin of the Olokit structure.

The interaction of hydrous fluids and melts with dry rocks of the lithospheric mantle inevitably modifies their viscoelastic and chemical properties due to the formation of compositionally distinct secondary phases. In addition, melt percolation and the associated metasomatic alteration of mantle rocks may also facilitate modification of the pre–existing rock texture and olivine crystallographic preferred orientation (CPO) and thus seismic properties. Here we explore the relationship between mantle metasomatism, deformation and seismic anisotropy using subduction–related mantle xenoliths from the Penghu Islands, western Taiwan. The investigated xenoliths have equilibrated at upper lithospheric mantle conditions (879 °C to 1127 °C) based on pyroxene geothermometry and show distinct variations in clinopyroxene chemical composition, texture and olivine CPO allowing for the classification of two distinct groups. Group 1 xenoliths contain rare earth element (REE) depleted clinopyroxene, show a porphyroclastic texture and olivine grains are mostly characterized by [100]–axial pattern symmetries. In contrast, REE-enriched clinopyroxene from Group 2 xenoliths occur in a fine–grained equigranular texture and coexisting olivine frequently displays [010]–axial pattern symmetries. The clinopyroxene compositions are indicative of cryptic and modal to stealth metasomatic alteration of Group 1 and Group 2 xenoliths, respectively. Furthermore, the observed olivine [100]–axial pattern of Group 1 xenoliths reflects deformation by dislocation creep at high temperature, low pressure and dry conditions, whereas olivine [010]–axial patterns of Group 2 xenoliths imply activation of olivine [001] glide planes along preferentially wet (010) grain boundaries. This correlation indicates that the variation in olivine CPO symmetry from [100]– to [010]–axial pattern in Penghu xenoliths results from deformation and intra-crystalline recovery by subgrain rotation during metasomatic alteration induced by melt percolation. The microstructural observations and olivine CPO combined with petrological and geochemical data suggest that Group 1 xenoliths preserve microstructural and chemical characteristics of an old, probably Proterozoic lithosphere, while Group 2 xenoliths record localized Miocene deformation associated with wall–rock heating and metasomatism related to melt circulation. Furthermore, the observed transition of olivine CPO from [100]–axial pattern to [010]–axial pattern by deformation in the presence of variable melt fractions and associated metasomatic alteration can be inferred to modify the physical properties of mantle rocks.

Background: Primary tumor resection for patients(pts) with de novo stage IV breast cancer(BC) was controversial among recent clinical trials. Indeed, considerable discrepancy in metastatic pattern between those studies was considered as a potential reason for their inconsistent results. We sought to determine the survival benefit of primary surgery on the basis of metastatic pattern. Methods: A retrospective cohort study based on the SEER database was conducted to identify pts with de novo stage IV BC diagnosed between 2010 and 2015. Pts were divided into a surgery and a non-surgery group, and propensity score weighting was used to balance clinicopathologic factors between groups. Results: Of 8,142 de novo stage IV BC pts with a total of 12,737 sites of distant metastases identified in this study, 1,891(23%) cases were managed with surgery and 6,251(77%) cases were managed without surgery. There were 3,821 all-cause deaths and 3,291 BC specific deaths over a median follow-up of 22 months. The weighted 3-year overall survival(OS) for the surgery group was 54.5%, compared to 47.7%(HR=0.82;0.78 to 0.86,P Hazard ratios comparing survival between surgery group and non-surgery group according to metastatic patterns.Metastatic patternNo. of Patients (Non-surgery group/Surgery group)Weighed* 3-year OS (%) (Non-surgery group/Surgery group)Weighed Multivariable*† HR of OSPWeighed* 3-year BCSS (%) (Non-surgery group/Surgery group)Weighed Multivariable*† HR of BCSSPDistant Lymph nodes-only285/19255/550.960.7164/581.160.2Bone-only2409/70454/640.83 Conclusion: The survival benefit offered by surgery for de novo stage IV BC varies by metastatic patterns. Local surgery for pts with bone-only metastasis or high metastatic burden accompanied by bone metastasis offers a significant survival advantage over non-operative management, whereas the opposite effect is observed among simultaneous liver and lung metastasis pts. Decisions for primary surgery of de novo stage IV BC pts should be tailored according to metastatic pattern, and mechanisms of bone/visceral organs-only/first metastasis BC are needed further understanding. Citation Format: Wang K, Shi Y, Zhang X, Ren G-S, Li H-Y. Metastatic pattern discriminates survival benefit of primary surgery for de novo stage IV breast cancer patients: A longitudinal cohort study [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-14-10.

High-grade metasedimentary rocks of the South Muya block (Baikal-Muya Foldbelt) have been studied with respect to whole-rock elemental and Nd isotopic compositions, as well as the U-Pb and Lu-Hf systematics of detrital zircon and in-situ grown metamorphic grains in order to reveal the initial source provenance for sedimentation and the age of major metamorphic modification. Based predominantly on trace-elemental compositions, the sedimentary protolith is most likely a poorly sorted and immature greywacke, such as those formed in island arc or active continental margin settings. The island arc-related chemical signature coupled with zircon U-Pb age data supports a Neoproterozoic (>760 Ma) sedimentation age, whereas Nd-Hf isotope data of precursor sediments are linked to a relatively immature Tonian (∼940–780 Ma) continental arc involving Paleoproterozoic crustal basement. The limited provenance information and metamorphic history of the Muya block suggests it was exotic to Siberia and originally related to another continent, e.g. – subduction-accretion complexes of South China. The polyphase metasediments experienced high-grade metamorphism in the Tonian during the 764–754 Ma arc accretion to an enigmatic continental block and then in the Ediacaran during the 622–608 Ma accretion of the Baikal-Muya belt to the arc situated at the southern Siberia margin. Metamorphic overprinting during the introduction of supracrustal rocks to deeper-crustal levels led to protracted recrystallization of primary igneous zircon population and growth of new granulite-facies grains that did not involve notable juvenile input. Tonian sedimentary provenance and two metamorphic events suggest a protracted evolution for the Baikal-Muya belt associated with the formation of precursor complexes beyond the southern margin of Siberia and their later accretion to Late Cryogenian – Ediacarian arc complexes of the southern Siberian, which proceeded only after the opening of the Paleoasian Ocean (670–630 Ma).

Palaeoproterozoic amphibole-biotite orthogneisses with a protolith age of ~ 1840 Ma and Neoproterozoic muscovite-chlorite orthogneisses with an estimated protolith age of ~ 790 Ma have been identified in the structure of the Zheltau terrane (Southern Kazakhstan; west Central Asian Orogenic belt). In addition, metasedimentary complexes represented by prevailing garnet-mica schists and subordinate muscovite-chlorite schists with obtained detrital zircon ages in the range of 604 - 2819 Ma (with two peaks at ~ 991 Ma and ~ 1082 Ma) also comprise the Zheltau terrane. In accordance with the Sm-Nd whole-rock isotopic compositions, the protolith of the observed Palaeoproterozoic orthogneisses formed as a result of a mixing of the Neoarchean crustal source with a juvenile source, whereas the formation of the Neoproterozoic orthogneisses protolith may have been related to the melting of Palaeoproterozoic crustal material. In turn, Late Mesoproterozoic – Early Neoproterozoic granitoids or felsic volcanic rocks, which formed as a result of the melting of Palaeoproterozoic continental crust, are considered as possible sources for the studied detrital zircons obtained from the schists. The terrigenous protolith of the schists from the Zheltau terrane accumulated in the range of ~ 600 to ~ 490 Ma, corresponding to the Ediacaran-Cambrian. Subduction processes in the Early Palaeozoic led to the burial of different horizons of the Zheltau terrane continental crust to significant depths; some of the complexes experienced high-pressure metamorphism at P 15 – 18 kbar; T 750 – 850 °C (high-pressure granulites), whereas most of the rocks were evidently metamorphosed at maximum amphibolite facies and avoided high-pressure re-equilibration. The spatial proximity of the studied metamagmatic and metasedimentary crustal complexes and similar metamorphic changes during the latest stages of retrogression imply their possible mutual exhumation from different levels during the period between 490 and 470 Ma and their following juxtaposition as a package of tectonic slices.

A comparison of the lithological–geochemical parameters for the deposits of the Dalnetaiga series of the Bodaibo synclinorium (the Buzhuikhta and Khomolkho formations) and the Olokit structural-formational zone (the Itykit and Ondok formations), hosting polymetallic deposits (Kholodnin, Ioko-Rybach’e), along with the obtained geochronological LA-ICP-MS U–Pb age estimates of the Ondok Formation (~600 Ma), indicates their similar stratigraphic position in the Neoproterozoic in Southern Siberia. At the first stage of formation of polymetallic and gold-ore objects, the siderochalcophylic trend is considered to have appeared synchronously in the two structural zones, which could have been caused by the hydrothermal activity in the back-arc basin of the Olokit structure.

The Tierra Blanca (TB) eruptive suite comprises the last four major eruptions of Ilopango caldera in El Salvador (≤45 ka), including the youngest Tierra Blanca Joven eruption (TBJ; ∼106 km3): the most voluminous event during the Holocene in Central America. Despite the protracted and productive history of explosive silicic eruptions at Ilopango caldera, many aspects regarding the longevity and the prevailing physicochemical conditions of the underlying magmatic system remain unknown. Zircon 238U‐230Th geochronology of the TB suite (TBJ, TB2, TB3, and TB4) reveals a continuous and overlapping crystallization history among individual eruptions, suggesting persistent melt presence in thermally and compositionally distinct magma reservoirs over the last ca. 80 kyr. The longevity of zircon is in contrast to previously determined crystallization timescales of, Plain Language Summary: The collapse of a volcano edifice into its shallow magma chamber can produce one of the most dangerous single events in nature, known as a caldera‐forming eruption. The TBJ eruption in El Salvador is of this kind and occurred around 1,500 years ago, having a profound impact on Maya societies. Because of this, it is crucial to understand the inner workings of caldera‐forming eruptions to assess volcanic risks and their mitigation. Beneath Ilopango caldera, the micrometer‐sized radioisotopically datable mineral zircon grew within different storage levels of a silica‐rich magma reservoir suggesting continuous melt presence for up to ca. 80,000 years prior to eruption. The time information given by zircon contrasts with that extracted from other, more abundant minerals from the same rocks (, Key Points: U‐Th zircon ages for the last four explosive eruptions of Ilopango caldera reveal a long‐lived magma reservoir (>80 kyr). Contrasting residence times for major minerals and zircon suggest extraction of zircon along with evolved melt from crystal residue. Melt extraction from vertically extensive, thermally zoned magma reservoir., Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659

The climactic Los Chocoyos (LCY) rhyolitic eruption from Atitlán caldera (Guatemala) is a key chronostratigraphic marker for the Late Quaternary period that has been widely used for relative dating of paleoenvironmental, paleoclimate, and volcanic events throughout Central America and adjacent marine basins in the Pacific Ocean, the Caribbean Sea, and the Gulf of Mexico. Despite LCY tephra being an important marker horizon, a radioisotopic age for this eruption has remained elusive. LCY tephra has been dated at ca. 84 ka BP based on its occurrence in marine sediments with model δ18O ages, but this inferred age has not been independently confirmed through radioisotopic methods. This is due to the inherent limitations of radiocarbon dating (which is practically limited to ˂50 ka) and a lack of suitable materials for 40Ar/39Ar analysis in LCY tephra. To overcome this limitation, we applied 238U-230Th and (U-Th)/He zircon double-dating (ZDD). Due to zircon being alteration-resistant this method establishes absolute chronologies for and correlations between silicic tephra deposits, which are unaffected by glass alteration or complex compositional signatures within a single eruption. 238U-230Th zircon crystallization rim ages were obtained from LCY proximal tephras (~17 km from Atitlán caldera) including sub-units that may bear distinct glass compositions (e.g., fallout, ignimbrite, surge) as well as ultra-distal fallout tephra samples (~300 km from source) collected from drill cores at Petén Itzá Lake (ICDP) and the Pacific Ocean (IODP). All samples yielded zircon with statistically indistinguishable 238U-230Th zircon rim age spectra. These reveal continuous zircon crystallization from ca. 160 ka to ca. 74 ka, with peaks in zircon crystallization between 90-100 ka. ZDD eruption ages from two LCY fallout and one ignimbrite deposit are indistinguishable with error-weighted averages of 75.1 ± 3.2 ka (1σ; n = 16; MSWD = 4.1), 76.0 ± 2.5 ka (n = 16; MSWD = 2.5), and 72.8 ± 3.5 ka (n = 16; MSWD = 3.7). Considering all individual zircon results as a single population, a weighted average ZDD age of 74.8 ± 1.7 (1σ; n = 48; MSWD = 3.3) is obtained and considered as the best estimate for LCY eruption age. GIS-based reassessment of LCY eruptive volume uses thickness information from new 113 outcrops including 6–10 m thick pyroclastic density currents in Chiapas, Mexico (>130 km from the source) and suggests a minimum estimate volume of ~1200 km3, confirming the LCY eruption as the first‐ever recognized supereruption in Central America. The new ZDD age of 74.8 ± 1.7 ka for the LCY eruption is significantly younger than the commonly cited O-isotope stratigraphic age of 84 ± 5 ka. This age is close to the voluminous (2,800-5,600 km3) Young Toba Tuff (YTT) supereruption at ca. 73.8 ± 0.3 ka from Toba Caldera, Indonesia. Both YTT and LCY eruptions have been previously linked to prominent Quaternary climate excursions. Based on the new LCY eruption age, climate-forcing effects that are usually attributed to YTT may in fact be exacerbated by another supereruption occurring within a short time window of the YTT event.

The Hellenic arc hosts several active volcanic centers, of which the Milos, Santorini-Kolumbo and Kos-Yali-Nisyros volcanic fields present particularly high threats due to recent unrest (2011-2012 and 1996-1997 at Santorini and Nisyros, respectively). These volcanic centers have repeatedly produced highly explosive eruptions (VEI 4 to 7) from ~360 ka into historic times. The marine tephra record provides information not only on the number of events, but also on their magnitudes and intensities inferred from tephra dispersal characteristics, and is thus essential to quantitatively assess future volcanic hazards and risks.Here we complement earlier work on distal to ultra-distal east-Mediterranean sediment cores, which captured the largest eruptions. We present results from a grid of medial to distal sediment cores collected in 2017 during RV Poseidon cruise POS513 with core positions both comparatively close to and between the three volcanic fields, in order to record medium- to large-scale eruptions.During this cruise, 47 gravity cores up to 7.4 m long, and 3 box cores of the uppermost 0.5 m sediment were recovered, which contain more than 220 primary ash layers. The compositions of glass shards from all layers were characterized by major (EMP) and trace-element (LA-ICPMS) analyses.Geochemical fingerprinting supports correlations with 20 eruptions from all three volcanic fields as well as with the 39 ka Campanian ignimbrite eruption from the Campi Flegrei, Italy. Correlations with eleven eruptions from Santorini-Kolumbo (Kameni, Kolumbo 1650, Minoan, Cape Riva, Cape Tripiti, Upper Scoria 1 and 2, Middle Pumice, Cape Thera, Lower Pumice, Cape Therma 3) are established, and we newly identify two widespread tephras from eruptions on Milos (Lower and Upper Firiplaka). We have probably been able to solve some previous chronostratigraphic problems at Kos-Yali-Nisyros by correlating marine tephras with the Kos Plateau Tuff, and with the Yali 2 tephra, whereby we identify a second, less evolved facies produced by that eruption that has not yet been recognized on land. We also find tephras from four eruptions on Nisyros (Nisyros 1 to 4) including the previously established Lower (Nisyros 4) and Upper (Nisyros1) Nisyros Pumice eruptions.These correlations also provide new age constraints for hitherto poorly or non-dated Aegean tephras based on sedimentation rates derived between multiple anchor points of dated terrestrial tephra ages. We deduce ages of ~22 ka and ~36 ka for Upper and Lower Firiplaka tephras from Milos (the latter overlying the Campanian ash) which are significantly younger than other eruption ages known from Milos, ~54 ka, ~62 ka, ~69 ka, and ~76 ka for the Nisyros 1 to 4 tephras, and ~52 ka for the Yali 1 tephra as well as a verified age of 33 ka for the Yali 2 tephra with its two contemporaneous facies.These new tephrostratigraphic results help to improve quantifications of distribution and eruption characteristics for all these eruptions, and provide important pre-site survey data for the Santorini IODP proposal VolTecArc.

The North Croatian Basin (NCB) evolved during the Miocene as a part of the SW margin of the Pannonian Basin (Carpathian-Pannonian Region, CPR). A major transgressive-regressive sedimentary cycle in the NCB is represented by an initial deposition in alluvial and lacustrine environments, followed by Central Paratethyan marine environments, and a subsequent return to lacustrine and alluvial depositional environments (Pavelić & Kovačić, 2018). Indications for these variable depositional conditions that are linked to the marine flooding of the NCB are preserved in sediments on Mt. Medvednica (Pavelić and Kovačić, 2018 ; Avanić, 1997). Due to the intensive and long-lasting CPR magmatic activity, numerous referent volcaniclastic layers are preserved in stratigraphically and environmentally different sedimentary facies. We applied an integrated stratigraphic, compositional and geochronological approach on the three volcaniclastic horizons (ČUČ-1, ČUČ-6, PL) intercalated within the marine sediments on Mt. Medvednica to determine the flooding history and the timing of the initial Miocene Central Paratethys transgression of the western part of NCB, as well as to enable the correlation of the volcaniclastic layers. Volcaniclastic deposits ČUČ-1 and ČUČ-6 are fine to coarse tuffs intercalated with massive marls. The sequence of calcarenite, tuff, and calcisiltites recorded at site PL indicate a gradual deepening of the marine environment. The composition of volcaniclastic samples from all three sites is similar, with dominantly > 50% vitric juvenile particles (pumice and volcanic shards) with subordinate magmatic minerals (feldspar, biotite, quartz, and amphiboles). The samples are well preserved, with rarely visible volcanic glass alteration. Rhyolitic glass compositions (>77% wt. SiO2 ; ranging from rhyolites to high-K rhyolites) from all 3 volcaniclastic horizons suggest an origin from major silicic eruptive events of the CPR. Future trace element measurements of glass shards will provide additional constraints to distinguish primary from secondary volcaniclastics. New high-precision CA-ID-TIMS U-Pb zircon dates indicate that the ČUČ-1 volcaniclastic horizon (up to 15.44 Ma) is older than the PL horizon (14.937 ± 0.012 Ma), as suggested by Avanić (1997). Since ČUČ-1 zircon dates range from 15.44 and 15.9 Ma, it is not possible to interpret a high-precision age, however, the absence of zircons younger than ~15.44 Ma implies the existence of NCB marine deposits older than ~14.8 Ma (Marković, 2017 ; PL this study). This data is also indicating that the initial Middle Miocene Central Paratethys flooding of the western (Mt. Medvednica) and the eastern (Mt. Požeška gora, Brlek et al. 2020) parts of the NCB occurred earlier than the previously accepted ~15 Ma maximum flooding age. References: Avanić, R. (1997): Analiza facijesa srednjeg miocena jugoistočnog dijela Medvednice, Master Thesis, University of Zagreb. Brlek, M. et al. (2020): Miocene syn-rift evolution of the North Croatian Basin (Carpathian-Pannonian Region): new constraints from Mts. Kalnik and Požeška gora volcaniclastic record with regional implications. International Journal of Earth Sciences 109:2775–2800. Marković, F. (2017): Miocene tuffs of the North Croatian Basin, Dissertation, University of Zagreb. Pavelić, D., Kovačić, M. (2018): Sedimentology and stratigraphy of the Neogene rift-type North Croatian Basin (Pannonian Basin System, Croatia): a review. Mar Pet Geol 91:455–469.

It is always tricky to definite deep-seated or massive scale landslide investigation and monitoring. The scars could map from a high-resolution digital elevation model. However, the activity or sliding depth is merely difficult to define before installing a monitoring system. Lantai potential landslide area is selected for testing and demonstrating newly developed scientific investigation and monitoring techniques. Possible landslide scars have mapped from airborne lidar data, which provided a reference area for DInSAR analysis. More than ten years of DInSAR analysis shows an active/fast-moving area. The sliding plane and geological structure defined from customized earthquake stations and UAV LiDAR following with field verification. The background noise detection can define potential sliding planes from various precipitation events or earthquakes. GPS/leveling stations are installed to monitor ground deformation and verification from DInSAR results providing single point information to the whole area. The drilling holes’ depth is determined from earthquake stations analysis result, geological data, and sliding model from preliminary numerical analysis. Resistivity poles are installed at two holes from 100m beneath the ground surface with connected poles between these two holes to form a window shape monitoring system. The window shape Resistivity Image Profiling system can measure continuously providing not only geological structure variance and groundwater passing this window. New developed optical-fiber water pressure gauges are installed at different depths to verified groundwater pressure and water flow. The deformation system including extensometer, MEMS inclinometer, In-Plane Inclinometer, and Shape Acceleration Array are installed to provide direct displacements from the ground surface to underground. The sliding threshold is thus defined with various measurements from different monitoring methods and with different scales.

The geochemistry, geochronology, and isotope geochemical systematics (Nd, Sr, Hf, and Pb) of the granitoids of the Pozdnestanovoy complex of the Dzhugdzhur–Stanovoy superterrane of the Central Asia fold belt were investigated. It was shown that their age is Mesozoic (142–138 Ma) rather than Early Precambrian, as was previously supposed. The main sources of parental melts for these granitoids were the Neoarchean and Paleoproterozoic rocks of the lower continental crust of the Dzhugdzhur–Stanovoy superterrane and the rocks of the Late Paleozoic–Early Mesozoic continental crust of the Amur microplate. They were formed at depths of >40 km and temperatures of 700–800°C, most likely through the melting of mafic feldspar granulites under the conditions of aqueous fluid infiltration without any significant contribution from a juvenile heat source. The granitoids of the Pozdnestanovoy complex were emplaced during the closure of the eastern segment of the Mongolia–Okhotsk Ocean owing to the collision of the Siberian and Sino-Korean continents.

The results of U—Th—Pb (LA-ICP-MS) geochronological studies of detrital zircons from terrigenous rocks of the Dzhida terrane of the Central Asian Fold Belt (CAFB) are presented. The data obtained allow us to distinguish the following age maxima (Ma): 578 and 634 (Vendian); 720, 823, and 919 (Late Riphean); 1922, 2090, 2225, and 2321 (Early Proterozoic). A number of zircons have Late Archean age in the interval of 2670–2980 Ma. Taking into account Late Cambrian age (504–506 Ma) of intrusive rocks that intruded the Dzhida terrane, a possible sedimentation period of sequences of this terrane is estimated to be in the interval of 580–510 Ma (from Vendian to Late Cambrian). The possible provenance areas of terrigenous sediments are proposed and the previously proposed models of geodynamic evolution of the Dzhida terrane are correlated with new geochronological data.

The Sanandaj-Sirjan Zone (SaSiZ) is a magmatic terrane within the Zagros Orogen, western Iran, marking the Tethyan suture zone between the Afro-Arabian Plate and the Central Iran Micro-Continent. Mafic-intermediate dyke swarms with Middle Jurassic (Group-1: hornblende gabbro and diorite) and Late Eocene (Group-2: hornblende-pyroxene gabbro) ages are recognized in the Malayer-Boroujerd Plutonic Complex of the northern SaSiZ. Group-1 dykes have elemental and isotopic signatures consistent with melting of a mantle source modified during Neo-Tethyan subduction. Some Group-1 magmas evolved to intermediate compositions through assimilation and fractional crystallization. Group-2 dykes have within-plate trace element geochemical signatures, modelled as deriving from low-degree melting of asthenospheric mantle without a subduction influence. Published models postulate either a Cretaceous-Eocene Neo-Tethyan flat-slab scenario, or a Latest Cretaceous-Palaeogene Neo-Tethyan break-off event beneath the SaSiZ. Such models do not reconcile with the Late Eocene presence of within-plate magmatism in westernmost Iran, very close to the Zagros Suture. We argue that a period of flat-slab subduction concluded with sub-parallel subduction of a Neo-Tethyan ridge to the trench. The resulting slab break-off event in the Late Eocene is responsible for generation of the distinct Mesopotamia and Zagros slabs in mantle tomography models. Break-off was followed by small volume within-plate type magmatism before short-lived re-establishment of Tethyan subduction prior to the final Arabia-Eurasia collision. Supplementary material: Field photographs, photomicrographs, additional geochemical plots, descriptions of analytical methods and tables of geochemical modelling parameters are available at https://doi.org/10.6084/m9.figshare.c.4126196.

We examine the importance of dispersed volcanic ash as a critical component of the aluminosilicate sediment entering the Nankai Trough, located south of Japan’s island of Honshu, via the subducting Philippine Sea plate. Multivariate statistical analyses of an extensive major, trace, and rare earth element data set from bulk sediment and discrete ash layers at Integrated Ocean Drilling Program (IODP) Sites C0011 and C0012 quantitatively determine the abundance and accumulation of multiple aluminosilicate inputs to the Nankai subduction zone. We identify the eolian input of continental material to both sites, and we further find that there are an additional three ash sources from Kyushu and Honshu, Japan and other regions. Some of these ash sources may themselves represent mixtures of ash inputs, although the final compositions appear statistically distinct. The dispersed ash comprises 38 ± 7 weight percent (wt%) of the bulk sediment at Site C0011, and 34 ± 4 wt% at Site C0012. When considering the entire sediment thickness at Site C0011, the dispersed ash component supplies 38000 ± 7000 g/cm2 of material to the Nankai subduction system, whereas Site C0012 supplies 20000 ± 3000 g/cm2. These values are enormous compared to the ~2500 g/cm2 (C0011) and ~1200 g/cm2 (C0012) of ash in the discrete ash layers. Therefore, the mass of volcanic ash and chemically equivalent alteration products (e.g., smectite) that are dispersed throughout the stratigraphic succession of bulk sediment appears to be up to 15–17 times greater than the mass of discrete ash layers. The composition of the dispersed ash component at Site C0011 appears linked to that of the discrete layers, and the mass accumulation rate for dispersed ash correlates best with discrete ash layer thickness. In contrast, at Site C0012 the mass accumulation rate for dispersed ash correlates better with the number of ash layers. Together, the discrete ash layers, dispersed ash, and clay-mineral assemblages present a complete record of volcanism and erosion of volcanic sources; and indicate that mass balances and subduction factory budgets should include the mass of dispersed ash for a more accurate assessment of volcanic contributions to large-scale geochemical cycling.

The subduction-related volcanic front in Nicaragua consists of the Tertiary “Coyol” member in the eastern highlands and the Quaternary to recent volcanic arc within the Nicaraguan depression. Although the Holocene to recent explosive volcanism has been studied extensively no detailed work has been done on the products of explosive volcanism from Quaternary volcanic complexes comprising also the Malpaisillo and Monte Galan Calderas, the focus of this study. The 11 km-wide Malpaisillo Caldera and ~3.5 km-wide Monte Galan Caldera, located ~50 km northwest of Managua, are surrounded by tens of meters of rhyolitic tephras. These pyroclastic flow and fall deposits extend proximally at least 11 km to the southeast and 23 km to the southwest, with observed depositional thicknesses of >16 m for a single ignimbrite unit (or >25 m for the entire section). Distal deposits are found as far as 350 km offshore in the Pacific. At least twelve highly explosive large-volume eruptive phases with corresponding tephra deposits (LPT = La Paz Centro Tephra, PPT = Punta de Plancha Tephra, LCbT = Lower Chibola Tephra, GT = Guacucal Tephra, UCbT = Upper Chibola Tephra, FeT = La Fuente Tephra, ST = Sabanettas Tephra, MgT = Miralago Tephra, ToT = Tolapa Tephra, LMT, MMT, UMT = Lower, Middle, and Upper Maderas Negras Tephras) are distinguished based on geochemical correlations and similar depositional characteristics. Radiometric 40Ar/39Ar ages indicate that most activity related to the large Malpaisillo Caldera occurred between ~570 and ~420 ka. The large Pleistocene Malpaisillo and Monte Galan Calderas are characterized by a long-lived history and, if evolved, a distinctly alkaline (K2O = 2.3–3.8 wt%; Na2O = 4.0–4.9 wt%) geochemical signature compared to the other Nicaraguan tephra deposits. As a result, the previously defined Malpaisillo Formation has been considerably extended and revised. Our findings contribute to fill a considerable gap in the long-term eruptive history of Nicaraguan volcanoes, with prominent implications for volcanic hazard evaluation for Nicaragua.

This work presents the results of U–Pb geochronological studies of alkaline granites of the Aralaul complex of Northern Kazakhstan, which allow one to substantiate their Late Silurian (420 ± 4 Ma) age. Taking into consideration the previously obtained data, we propose a new development scheme of Paleozoic granitoid magmatism in Northern Kazakhstan, which includes Late Ordovician granite–granodiorite (Zerenda and Krykkuduk), Early Silurian granite–leucogranite (Borovoe and Karabulak), Late Silurian granosyenites–granite (Aralaul), and Early Devonian (Balkashino and Orlinogorsk) complexes.

We report combined U Pb ages, Hf isotopes, and trace-element compositions of 116 mantle zircon megacrysts from the unusual diamond-bearing sedimentary rocks of the northeastern Siberian craton to constrain the age and geochemical affinity of their parental rocks as well as their possible relationship to diamond-rich placers of northern Yakutia. The textures, trace-element systematics, and 206Pb 238U dates of zircon megacrysts are evidence of their formation from kimberlites or related alkaline mantle melts and are similar to those of zircon from most Siberian kimberlites. The exclusively Triassic ages of zircon (247–202 Ma) fit the Triassic kimberlite eruption ages and those of related ultramafic-mafic magmatism in northern Siberia, which has conventionally been considered to sample the diamond-barren Proterozoic subcontinental lithospheric mantle. The chemical compositions of zircon megacrysts largely overlap with those of mantle zircon from both diamondiferous Paleozoic and diamond-barren Late Triassic and Late Jurassic kimberlite fields and indicate kimberlitic parental melts of significantly variable composition. Zircon megacrysts reveal 176Hf/177Hf heterogeneities (eHf(t) of +1.7 to +10.5), which, combined with a range of parental melt compositions, favor a chemically-heterogeneous sublithospheric source, which comprises a mixture of moderately depleted peridotitic and enriched pyroxene-rich (pyroxenitic, lherzolitic, or eclogitic) domains. As favored mechanisms, local incipient melting of variable degrees and carbonate-dominated melt fractionation en route to the surface might produce alkaline melts of contrasting bulk compositions within a spatially-limited mantle section. The zircon observations in this study indicate that the Triassic Bulkur rocks as well as – potentially – all the diamond-rich placers in northeastern Siberian craton may be sourced from one or a few coeval occurrences of unexposed kimberlites, which should have sampled the yet diamondiferous Triassic mantle. Considering the existing data for placer diamonds and specific K-Fe-Ti enriched composition of kimberlites in northeastern Siberian craton, we propose that chemical and Lu Hf isotopic signatures of the Bulkur zircon, bulk kimberlite compositions and diamond growth and storage in northeastern Siberia might be governed by the same processes of Mesozoic interaction between the hot ascending asthenosphere, oceanic slabs and lower cratonic lithosphere.