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When the lightweight quartz fiber-reinforced phenolic (LQFRP) composite is subjected to the combined effect of a local structural heat source and high-speed airflow, its ablation behavior exhibits significant localized characteristics and strong coupled effect. In this study, we have developed a bidirectional loosely coupled numerical model that integrates thermal, fluid, solid and ablation phenomena to solve the ablation-through problem of the LQFRP composite. The model takes into account the mechanisms of pyrolysis, oxidation, sublimation, and thermal mechanical erosion that occur during the ablation process of the LQFRP composite. The results suggest that the local structural heat source plays a crucial role in the erosion and retreat of the LQFRP composite. The morphology of the ablation pit shows a noticeable asymmetry, which is attributed to the aerodynamic heat and force. As a result of the local structural heat source, the fluid temperature downstream of the ablation pit is higher compared to that upstream of the ablation pit. The fluid that flows downstream of the ablation pit undergoes significant compression, leading to the formation of an oblique shock wave. The distribution of resin pyrolysis degree within the LQFRP composite is influenced by internal heat conduction. This study will offer valuable insights and guidance for the practical application of the LQFRP composite in the ultra-high temperature field. [ABSTRACT FROM AUTHOR]

Eruptive dynamics is influenced by gas escape from the ascending magma. Gas pathways form in the magma via bubble coalescence, leading to gas channeling. Magmatic crystals play a key role in gas channel formation. This work constrains experimentally decompression‐induced coalescence in high‐crystallinity silicic magmas without external deformation, focusing on low gas content and bimodal crystal size (microlites and phenocrysts). All percolating samples have permeabilities of 10−14 m2 at bulk porosities of 7–10 vol% and bulk crystallinities up to 75 vol%. Our results demonstrate the possibility of coalescence‐related outgassing at high pressure (120–350 MPa) and without external strain, which corresponds to magma stagnating deep in a volcanic conduit. Channeling at such low gas content implies that bimodal crystallinity favors effusive over explosive volcanic behavior. It may also be the missing physical mechanism explaining gas transfer across magmatic systems despite high melt viscosity and low or absent magma extrusion. Plain Language Summary: The way volcanoes erupt is mainly controlled by the ability of gases to escape from the magma (outgassing). An efficient way to outgas is to connect bubbles together (coalescence) up to the point where channels form in the magma (channeling) in which gas can circulate toward the surface. We investigate experimentally how coalescence and channeling happen in immobile, crystal‐rich viscous magma in conditions (pressure and temperature) similar to those found in deep volcanic conduit, where only a small amount of gas (<10%) is present. Our experiments demonstrate that bubble connections are possible thanks to a large amount of crystals on which bubbles can lean, deform, and join each other. That gas can escape from magma at depth could favor effusive eruption over volcanic explosions and even bring new insights on degassing in immobile magma. Key Points: Gas permeability in silicic magma is possible with gas volumes below 10% thanks to high crystallinityOutgassing at low gas content can happen without external deformation nor fracturation of the magmaVolcanic outgassing in stagnant magmas is explained by deep conduit bubble channeling that may be a key mechanism in eruptive transition [ABSTRACT FROM AUTHOR]

FeO is an important component in both mantle silicates and core iron alloys. Understanding its melting behavior and physical properties is crucial for exploring the chemistry and physics of our planet. Here we report the melting curve of FeO up to 186 GPa from laser‐heating experiments in a diamond‐anvil cell coupled with synchrotron X‐ray diffraction (XRD) techniques. In‐situ observations of both temperature plateau and changes in XRD patterns were used as primary melting criteria. The ex‐situ examination of a recovered sample shows consistent melting temperatures of FeO with in‐situ determinations. Our melting curve of FeO agrees with existing low‐pressure data within uncertainties and is much lower than earlier experimental results above 100 GPa including those extrapolated by Lindemann's law. Our results indicate that FeO‐rich materials could be present as melts coexisting with surrounding solids in the lowermost mantle, providing plausible explanations to the seismically observed ultra‐low velocity zones. Plain Language Summary: As an endmember of mantle silicates, the melting behavior of FeO is critical to understand the early magma ocean crystallization as well as present mantle signatures. However, the question on the high‐pressure melting curve of FeO remains because of the use of different melting criteria in earlier experiments. In this study, we conducted melting experiments on FeO up to 186 GPa in a laser‐heated diamond‐anvil cell using both in‐situ synchrotron X‐ray diffraction techniques and supplementary ex‐situ analyses of a recovered sample. Our results show that the melting temperature of FeO is 3,440 ± 250 K at 135 GPa, the Earth's core‐mantle boundary (CMB) pressure. The MgO‐FeO‐SiO2 melting phase diagram shows that fractional crystallization of mantle silicate melts would end up with a cotectic ternary minimum containing up to 95 mol% FeO, which would have a similar or slightly lower melting temperature than FeO. Considering the temperature at present‐day CMB, we anticipate that FeO‐rich materials, possible products of late‐stage magma ocean crystallization, would still exist as melts with surrounding solids at the bottom of the mantle. Due to its liquid nature and high density, the existence of FeO‐rich melts above the CMB could provide important insights for explaining the seismologically observed ultra‐low velocity zones. Key Points: The melting curve of FeO was determined up to 186 GPa based on in‐situ observations with supplementary ex‐situ examinationsOur determined melting temperature of FeO is much lower than earlier experimental results above 100 GPaAt the late magma ocean crystallization, the residual FeO‐rich materials could exist as melts in the lowermost mantle and explain ultra‐low velocity zones [ABSTRACT FROM AUTHOR]

This paper presents the integration of magnetic susceptibility measurements and whole-rock geochemical compositional and Nd–Sr isotopic ratio analyses for granite samples collected from the Ranong, Lam Pi, Ban Lam Ru, and Phuket granite bodies in the Western Granitoid Belt of Thailand. In addition, U–Pb dating was performed on zircons extracted from the samples. All samples are proper granites based on their mineralogical and geochemical characteristics. Two samples collected from the Lam Pi granite body were classified as magnetite-series and I-type. The remaining granite samples were classified as ilmenite-series and S- or A-type. Furthermore, all granites were classified as syn-collision granites. Excluding the magnetite-series samples from the Lam Pi granite body, the other samples exhibit enrichment in incompatible elements, such as Nb, Sn, Ta, Pb, Bi, Th, U, Ce, Rb, and Cs. Zircon U–Pb dating yielded ages of ca. 60 Ma for the magnetite-series granites from the Lam Pi granite body, whereas ages of 88–84 Ma were obtained for the other granite bodies. Initial Nd–Sr isotopic ratios indicate a higher contribution of mantle material in the Lam Pi magnetite-series granites and a higher contribution of continental crust material in the other granites. Based on these compositional and zircon U–Pb age data, it is inferred that the 88–84 Ma granites formed as a result of the thickening of the continental crust owing to the collision between the Sibumasu and the West Burma blocks. In contrast, the ca. 60 Ma Lam Pi magnetite-series granites are thought to have been generated via partial melting of the mantle wedge associated with the subduction of the Neo-Tethyan oceanic crust beneath the West Burma Block. [ABSTRACT FROM AUTHOR]

Recently, a large-scale gas reservoir was discovered in granitic buried hills of the Songnan Low Uplift in the Qiongdongnan Basin. However, the strong heterogeneity of granite reservoirs limits further exploration and evaluation. Based on observations of sixty core samples and sixty thin sections, mineral composition, zircon dating, apatite fission tracks, physical properties, image logs, outcrop surveys and seismic interpretations, the characteristics of granite weathering crust of the Songnan Low Uplift are analyzed, and its controlling factors and evolution process are evaluated. The results show that weathered granite in the study area can be divided into several zones, from top to bottom: eluvium–slope zone, sandy zone, weathered fracture zone and horizontal undercurrent vuggy zone. The reservoirs in the eluvium–slope zone are dominated by microfissures and intergranular dissolution pores and have an average porosity of 4.68% and permeability of 2.34 md; the reservoirs in the sandy zone are composed of intergranular and intragranular dissolution pores and have an average porosity of 11.46% and permeability of 4.99 md; the reservoirs in the weathered fracture zone consist of various fractures and have an average porosity of 3.91% and permeability of 2.5 md; the reservoirs in the horizontal undercurrent vuggy zone are subhorizontal fractures and vugs and have an average porosity of 2.7% and permeability of 0.23 md. The development of granite reservoirs is jointly influenced by petrology and minerals, long-term exposure in a warm humid paleoclimate, faults, diverse topographies and shallow buried depth. Based on the above, our study establishes a development model of weathering crust and suggests that only the gentle slope and platform remain strongly weathered zones. After undergoing a complex evolution process of formation–destruction/denudation–regeneration–preservation, the current weathering crust of the Songnan Low Uplift is finally established. The results of this study have important theoretical and application value for the hydrocarbon exploration of buried hills in the Qiongdongnan Basin and provide a reference example for other granite reservoirs worldwide. [ABSTRACT FROM AUTHOR]

Madagascar is globally recognized as an important producer of high-quality flaky graphite. However, current research on graphite deposits in Madagascar remains insufficient. Previous studies have linked the genesis of Madagascan graphite deposits to the metamorphism of sedimentary organic matter. Here, we provide a case study of graphite deposits in Madagascar, combining new data from the Ambahita graphite deposit (AMG) in southern Madagascar with data from the Antanisoa graphite deposit (ANG) in central Madagascar and the Vohitasara graphite deposit (VOG) on the east coast of Madagascar. We note that the mineral assemblages of graphite-bearing rocks in the AMG, ANG, and VOG are not typical of metamorphic mineral assemblages but rather the results of filling and metasomatism by mantle-derived fluids that occurred after peak metamorphism. Electron microprobe analysis indicates that the graphite of the AMG, VOG, and ANG is usually associated with phlogopite or Mg-biotite; the phlogopite shares a common genesis with other widespread phlogopite deposits across Madagascar. We reveal that the distribution of graphite deposits in Madagascar is primarily controlled by ductile shear zones between blocks. Ductile shear zones that extend deep into the mantle can provide an ideal migration channel and architecture for the emplacement of mantle-derived fluids. The graphite mineralization formed no earlier than the peak metamorphism (490 Ma) and no later than the intrusion of pegmatite veins (389 ± 5 Ma). The distribution of graphite deposits, graphite orebody morphologies, mineral associations, and geochemical data suggest that the genesis of graphite deposits in Madagascar is linked to mantle-derived fluid filling rather than the metamorphism of sediments, as previously suggested. These findings have important implications for similar deposits in Madagascar and potentially globally. [ABSTRACT FROM AUTHOR]

The Kangjiawan Pb-Zn deposit, situated within the Shuikoushan polymetallic ore field in Changning, Hunan Province, China, is a large-scale Pb-Zn deposit unearthed in 1976. Based on detailed geological field investigations, this study presents the results of the Rb-Sr isotopic dating, electron probe microanalyses (EPMAs), and LA-ICP-MS analyses of the Kangjiawan Pb-Zn deposit in order to determine the ore-forming age and the occurrence of trace elements in sphalerite and thereby constrain the genesis of the deposit. The Rb-Sr dating of quartz-hosted fluid inclusions yielded an Rb-Sr isochron age of 150 ± 4 Ma, with an initial 87Sr/86Sr ratio of 0.71101 ± 0.00008 (MSWD = 1.1), suggesting that the Pb-Zn mineralization of the Kangjiawan deposit took place during the Late Jurassic, coeval with the magmatic activities within the ore field. EPMA and LA-ICP-MS analyses showed that Fe, Mn, and Cd were primarily incorporated into the sphalerite lattice through isomorphous substitution. Specifically, Fe and Mn substituted for Zn, whereas Cd replaced both Fe and Zn. Other elements such as Cu, Sb, and Sn occurred within the sphalerite lattice through mineral micro-inclusions or isomorphic substitution. EPMAs and LA-ICP-MS results showed that the FeS contents in sphalerite were less than 14.33%, with corresponding ore-forming temperatures below 259 °C. The LA-ICP-MS results showed that sphalerites from the Kangjiawan Pb-Zn deposit had relatively high Ga/In ratios ranging from 0.01 to 144, providing further support for medium-to-low-temperature mineralization. The trace element compositions of sphalerites from the Kangjiawan Pb-Zn deposit exhibit skarn-type characteristics, suggesting a potential association with contemporary magmatic activities within the Shuikoushan ore field. During the Late Jurassic, extensive granitic magmatic activities occurred in the study area. At the late stage of magma crystallization, hydrothermal fluid containing Pb and Zn precipitated at medium-to-low temperatures and generated the Kangjiawan Pb-Zn deposit. [ABSTRACT FROM AUTHOR]

The late Paleozoic tectonic setting of the Zongwulong Belt (ZWLB), a significant unit located in the northern Qaidam margin, Qinghai province, remains uncertain. Diabase dykes in the western part of the Zongwulong Belt offer insights into this issue. Field investigations reveal that the dips of the dykes are almost vertical, and they have sharp boundaries with the host rocks. These dykes consist of plagioclase, clinopyroxene, and opaque minerals exhibiting a characteristic porphyritic texture and massive structure. Zircon U-Pb dating of the dykes yields a weighted 206Pb/238U age of 289 ± 1 Ma. The dykes exhibit relatively high concentrations of TFeO, K2O + Na2O, and TiO2, while the SiO2 and MgO concentrations are relatively low. They display relative light-over-heavy REE enrichment, and lack negative Nb-Ta and Eu anomalies. The dykes underwent negligible crustal contamination, and experienced extensive fractional crystallization of olivine, clinopyroxene, and Fe-Ti oxides. Originating from the spinel–garnet transition zone at depths of approximately 75 km, the dykes result from garnet facies low-degree melting (5%–10%) in a continental rift setting. Combining these findings with regional geological data, we propose that the ZWLB likely experienced a continental rift in the west and exhibited a narrow oceanic environment in the east in the late Paleozoic period, potentially representing the most distant north branch of the East Paleo-Tethys Ocean. [ABSTRACT FROM AUTHOR]

The kinematics and deformation pattern along the Altyn Tagh fault (ATF), one of the largest strike‐slip faults on Earth is of great significance for understanding the growth of the Tibetan Plateau. However, the initial rupture along the ATF remains debated given the limited constraints on the depositional age of associated Cenozoic syntectonic strata. Here we investigated the syntectonic Cenozoic strata in the Xorkol Basin, associated with the strike‐slip faulting along the ATF. New uranium‐lead analyses of the carbonate deposits in the Paleogene strata yield dates of 58.9 ± 1.29 Ma, representing the initial rupture of the ATF. This first documented radioisotopic age coincides with the ca. 60 Ma onset timing of India‐Asia collision, highlighting its far‐field effect at the northern edge of the Tibetan Plateau. We infer that the deformation of the entire Tibetan Plateau started synchronously with the India‐Asia collision. Plain Language Summary: Carbonate U‐Pb dating techniques applied to rocks associated with the Altyn Tagh fault, a major fault in North Tibet, reveal that the fault started slipping about 58.9 million years ago, coinciding with the time when India collided with Asia. This finding provides new constraints on when and where this fault formed and suggests that the northern Tibetan Plateau started deformation earlier than previously thought. This result emphasizes that the entire Tibetan Plateau deformed simultaneously in the early Cenozoic. Key Points: Calcite U‐Pb dating yields ca. 59 Ma age for carbonate strata in the East Xorkol BasinXorkol Basin was a pull‐apart basin during the Paleocene due to the left‐lateral strike‐slip faulting along the Altyn Tagh faultWidespread Paleocene‐Eocene tectonism in Northern Tibet highlights the far‐field effect of the India‐Asia collision [ABSTRACT FROM AUTHOR]

The chemical and pore structures of coal play a crucial role in determining the content of free gas in coal reservoirs. This study focuses on investigating the impact of acidification transformation on the micro-physical and chemical structure characteristics of coal samples collected from Wenjiaba No. 1 Mine in Guizhou. The research involves a semi-quantitative analysis of the chemical structure parameters and crystal structure of coal samples before and after acidification using Fourier Transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) experiments. Additionally, the evolution characteristics of the pore structure are characterized through high-pressure mercury injection (HP-MIP), low-temperature nitrogen adsorption (LT-N2A), and scanning electron microscopy (SEM). The experimental findings reveal that the acid solution modifies the structural features of coal samples, weakening certain vibrational structures and altering the chemical composition. Specifically, the asymmetric vibration structure of aliphatic CH2, the asymmetric vibration of aliphatic CH3, and the symmetric vibration of CH2 are affected. This leads to a decrease in the contents of -OH and -NH functional groups while increasing aromatic structures. The crystal structure of coal samples primarily dissolves transversely after acidification, affecting intergranular spacing and average height. Acid treatment corrodes mineral particles within coal sample cracks, augmenting porosity, average pore diameter, and the ratio of macro-pores to transitional pores. Moreover, acidification increases fracture width and texture, enhancing the connectivity of the fracture structure in coal samples. These findings provide theoretical insights for optimizing coalbed methane (CBM) extraction and gas control strategies. [ABSTRACT FROM AUTHOR]

During the Late Palaeozoic to Early Mesozoic, the eastern segment of the Palaeo–Tethys Ocean closed, resulting in the collision and amalgamation of the South and North Hainan Islands. However, the exact location of the collision and amalgamation remains controversial. The main collision locations are the Baisha, Jiusuo–Lingshui and Changjiang–Qionghai faults. The U–Pb age of detrital zircons was used to determine the main source area of the Middle Triassic basin in the eastern part of Hainan Island and the closed position of the eastern section of the Palaeo‐Tethys Ocean. The U–Pb dating of detrital zircons revealed that the Middle Triassic Lingwen Formation contains four age groups: 235–258, 335–446, 766–986 and >1000 Ma. Notably, rock masses aged 248–252 Ma that were formed in a post‐orogenic tension setting have been identified in the western region of Hainan Island, whereas no igneous rocks from this period have been discovered in the eastern region. The detrital zircon samples from the Lingwen Formation revealed a peak at 249 ± 2 Ma U–Pb age, which is important evidence indicating that the Changjiang–Qionghai Fault is the product of collision between the southern and northern Hainan terranes. Affected by the bipolar subduction of the eastern segment of the Palaeo‐Tethys Ocean, the collision and amalgamation of the South and North Hainan terranes occurred, and experienced a post‐collision (extensional) process at ca. 249 ± 2 Ma. [ABSTRACT FROM AUTHOR]

The Bengal Basin is a well‐known foreland basin that archives the tectonic evolution of the Himalayan and Indo‐Burman Ranges (IBR). The Dupi Tila Formation is the youngest among the stratigraphic successions of the Bengal Basin, which witnessed the last phase of the Himalayan uplift. However, there is still controversy regarding sediment provenances since the Himalayan and IBR are in the late Neogene exhumation stage. In this study, the petrographical and geochemical compositions of the Dupi Tila sandstones from the Lalmai Anticline of the Bengal Basin are examined to infer the source rocks, tectonic settings, palaeoclimate and weathering intensity in provenance areas. The detrital modes and geochemical discriminations, as well as Chondrite‐normalized rare earth elements patterns with enrichment in light rare earth elements and nearly flat heavy rare earth elements and negative Eu anomalies (average Eu/Eu* = 0.77) indicate dominantly felsic source rocks. The geochemical data also suggest that these source rocks in provenance areas were influenced by weak to moderate chemical weathering (chemical index of alteration: 65.64–75.62) and multiple recycling under warm and humid to semi‐humid climatic conditions. The detrital zircon ages show three dominant peaks at ca. 100, 500 and 1000 Ma with minor 1700 Ma. The amount of young zircon grains (<120 Ma) is noticeably higher (~18%) in this Lalmai outcrop compared to the Dupi Tila samples from the Sylhet Trough and Chittagong‐Tripura Fold Belt. Results from integrated zircon geochronology and geochemistry indicate that the detritus are likely derived from a recycled orogen provenance related mainly to active continental margin setting with subordinate influence from passive setting. Therefore, the regionally extensive Himalayan Orogen appears to be the primary sediment source, with additional mixing from the IBR and recycled sediments originating from the Gangdese batholith of the Trans‐Himalaya. [ABSTRACT FROM AUTHOR]

The spatiotemporal coupling relationship between deep hydrocarbon fluid and sandstone uranium mineralization within the shallow buried red‐variegated clastic rocks in the Qianjiadian area of the Songliao Basin remains a topic of controversy. This paper aims to provide a comprehensive understanding of the source, nature and exudative age of deep exotic hydrocarbon, as well as the interaction mechanism and alteration process between hydrocarbon fluid and clastic rock. To achieve this, various methods were employed, including acidolysis hydrocarbon test (AHT), clay x‐ray diffraction (XRF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), carbon isotope analysis (CIA) and LA‐ICP‐MS U–Pb isotopic dating. The results indicate that some tight sandstones from the Qingshankou Formation in Dalin uranium deposit exhibit high acidolysis hydrocarbon content (AHC), reaching n × 104 μL/kg, and predominantly consisting of low mature oil‐type gas. Local microscopic observations reveal pore fluorescence and hydrocarbon‐bearing inclusions with nattier blue tone. Furthermore, the kaolinites present in the ore area's sand‐bodies show a significantly higher content anomaly, commonly exceeding >50%, compared to the same layer in peripheral regions. Extensive dissolutions of lithic grains and feldspars are observed, along with the widespread occurrence of ferro‐dolomites and colloidal pyrites. Additionally, exotic asphaltenes are sporadically developed in localized areas. These findings provide evidence that the sand‐bodies experienced a significant exfiltration event of external gaseous fluids. The light carbon isotopes (δ13CV‐PDB ranging from −33.26‰ to −30.06‰) of group components and n‐Alkane suggest that the hydrocarbon originates from the source rock of the Lower Cretaceous Jiufotang Formation. A detailed two‐stage alteration sequence caused by acidic and reducing hydrocarbon is clarified, encompassing acidic corrosion, kaolinization, pyritization, silification and asphaltization during the exudation stage, followed by ferro‐dolomitization in the later cessation stage. Notably, vermicular secondary kaolinites, formed through the interaction between acidic hydrocarbon fluid and low‐temperature meteoric groundwater, serve as significant markers for the exfiltration of deep hydrocarbon fluid. In‐situ U–Pb dating of hydrocarbon‐bearing ferro‐dolomite yielded absolute exfiltration ages of 63.54 ± 4.13 and 65.93 ± 3.35 Ma. By integrating the tectonic–sedimentary–fluid evolution history and uranium mineralization characteristics in the study area, a three‐stage superimposed metallogenic model is proposed for the Upper Cretaceous red‐variegated layers: (1) the sedimentary and diagenetic stage of the target layer during the Late Cretaceous, (2) the predominant hydrocarbon exudation stage at the end of the Late Cretaceous, and (3) the main uranium mineralization stage since the Paleogene. This study enhances our understanding of coupled‐genetic sandstone‐type uranium deposit in a sedimentary basin and provides valuable guidance for prospecting similar red‐variegated beds in the Songliao Basin and other sedimentary basins worldwide. [ABSTRACT FROM AUTHOR]

The unexpected discovery of felsic magma by the Iceland Deep Drilling Project-1 (IDDP-1) in the Krafla volcanic system (KVS) presents a unique opportunity to investigate pre-eruptive lithium (Li) dynamics and establish a more direct connection between magma reservoirs and volcanic deposits. Our study provides new insights into Li abundances and isotope compositions in bulk-rock, minerals, and groundmass glass from rhyolitic lavas at KVS, encompassing various stages of groundmass crystallisation. Additionally, we examined felsic cuttings retrieved from the IDDP-1 well, comprising crystal-poor obsidian and crystal-bearing to -rich 'felsite' particles. Groundmass glasses from surface lavas show limited variability in K/Na, indicating limited secondary hydration of the glasses and that their Li contents seem to not be affected by this post-eruptive process. Lithium inventories in groundmass glasses and minerals within lavas exhibit variations consistent with the cooling history of the deposit, resembling patterns seen in Snake River Plain ignimbrites. Lithium contents of glassy rhyolitic lavas, whether bulk-rock (avg. 27.2 ± 3.1 μg/g) or groundmass glass (average 28.4 ± 4.7 μg/g), and their bulk isotopic compositions (avg. δ7Li =+ 4.4 ± 0.2‰) overlap with those observed in IDDP-1 obsidian cuts (avg. 24.9 μg/g Li in bulk, 28.6 ± 1.5 μg/g in groundmass glass, and δ7Li = 4.5 ± 0.2‰). Glassy lavas lacking spherulites may potentially preserve pristine magmatic Li element and isotope compositions, while areas with extensive groundmass crystallisation reveal Li enrichments in phenocrysts. Plagioclases in slowly cooled parts of the deposit record a two-fold increase in Li contents compared to plagioclase found in glassy counterparts, along with evidence of open-system degassing marked by heavier bulk Li isotope compositions and lower bulk Li contents of the crystallised lava portions (avg. δ7Li = +7.2 ± 0.1‰ and 7 ± 0.8 μg/g Li) relative to bulk glassy lithologies (avg. δ7Li = +4.1 ± 0.1‰ and 28 ± 2 μg/g Li). Partition coefficients derived from IDDP-1 cuts successfully predict Li inventories in vitrophyres of rhyolites on the surface of the KVS. Lithium isotope compositions of the crystal-rich IDDP-1 cuts are significantly heavier (avg. δ7Li = +7.2 ± 0.2‰) than lavas and IDDP-1 obsidian cuts, casting doubt on the notion that the IDDP-1 rhyolitic magma could result from the melting of felsite lenses in the KVS. Lithium contents in groundmass glasses within IDDP-1 crystal-rich cuts show higher Li contents (avg. 55.1–60.7 μg/g), correlating with the higher crystal content and an increase in other incompatible elements (avg. 250 μg/g Rb) relative to obsidian cuttings (avg. 75 μg/g Rb). [ABSTRACT FROM AUTHOR]

The Komsomolsk tin-ore district is located along the Miao-Chan Ridge in the Middle Amur River area (Khabarovsk krai) within the Badzhal accretionary terrane of the Sikhote-Alin orogenic belt. This work presents new results of U–Pb zircon dating of tonalite from the Miao-Chan complex of the Silinka granite pluton (99.7 ± 1.1 Ma) and rhyolites of the lower part of the Kholdami Formation (98.4 ± 1.0 and 98.7 ± 1.2 Ma) from the northeastern part of the Komsomolsk district. The geochemical characteristics of the rocks studied show that granitoids of the Miao-Chan complex are I-type rocks and that synchronous rhyolites of the Kholdami Formation are highly aluminous and correspond to S-type rocks. New data on the composition and early Cenomanian age of the rocks make it possible to consider the ore-magmatic system of the Komsomolsk ore district as part of the previously identified Albian–Cenomanian igneous province of Pacific Asia. [ABSTRACT FROM AUTHOR]

While thermochronological studies have constrained the landscape evolution of several of the crustal blocks of West and East Antarctica, the tectono-thermal evolution of the Ellsworth Mountains remains relatively poorly constrained. These mountains are among the crustal blocks that comprise West Antarctica and exhibit an exceptionally well-preserved Palaeozoic sedimentary sequence. Despite the seminal contribution of Fitzgerald and Stump (1991), who suggested an Early Cretaceous uplift event for the Ellsworth Mountains, further thermochronological studies are required to improve the current understanding of the landscape evolution of this mountain chain. We present new zircon (U–Th) / He (ZHe) ages, which provide insights into the landscape evolution of the Ellsworth Mountains. The ZHe ages collected from near the base and the top of the sequence suggest that these rocks underwent burial reheating after deposition. A cooling event is recorded during the Jurassic–Early Cretaceous, which we interpret as representing exhumation in response to rock uplift of the Ellsworth Mountains. Moreover, our results show that while ZHe ages at the base of the sequence are fully reset, towards the top ZHe ages are partially reset. Uplift and exhumation of the Ellsworth Mountains during the Jurassic–Early Cretaceous was contemporaneous with the rotation and translation of this crustal block with respect to East Antarctica and possibly the Antarctic Peninsula. Furthermore, this period is characterized by widespread extension associated with the disassembly and breakup of Gondwana, with the Ellsworth Mountains playing a key role in the opening of the far southern Atlantic. Based on these results, we suggest that uplift of the Ellsworth Mountains during the disassembly of Gondwana provides additional evidence for major rearrangement of the crustal blocks between the South American, African, Australian and Antarctic plates. Finally, uplift of the Ellsworth Mountains commenced during the Jurassic, which predates the Early Cretaceous uplift of the Transantarctic Mountains. We suggest that the rift-related exhumation of the Ellsworth Mountains occurred throughout two events: (i) a Jurassic uplift associated with the disassembly of southwestern Gondwana and (ii) an Early Cretaceous uplift related with the separation between Antarctica and Australia, which is also recorded in the Transantarctic Mountains. [ABSTRACT FROM AUTHOR]

Simultaneous U–Pb and U–Th dating using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was performed on the ca. 0.1 Ma Toya tephra and the ca. 0.08 Ma SS14-28 U–Th zircon reference material. In U–Pb dating, both Th/U and Pa/U partitioning between magma and minerals were considered. In U–Th dating, both abundance sensitivity and molecular interferences on 230Th were reevaluated. As a result, the Toya tephra yielded an accurate weighted mean U–Pb age of 0.103 ± 0.029 Ma (2σ) using zircon and monazite. Conversely, the SS14-28 zircon yielded an inaccurate U–Pb age (0.25 ± 0.10 Ma), which was attributed to low 206Pb signal intensity. Both the Toya tephra zircon and the SS14-28 zircon yielded accurate U–Th model ages of 0.108 ± 0.014 Ma and 0.078 ± 0.007 Ma, respectively. The agreement of U–Pb and U–Th ages for Toya indicates that simultaneous U–Pb and U–Th dating is possible and viable. The inappropriate age of SS14-28 U–Pb age and appropriate U–Th model age also indicates it is preferable to apply both U–Pb and U–Th dating simultaneously for young (<0.4 Ma) zircons to check internal consistency. The proposed double dating approach may be especially useful for small grains when it otherwise would be impossible to obtain multiple ages from a single grain. By adopting simultaneous U–Pb and U–Th dating using LA-ICP-MS, zircon crystallization ages as old as 4.5 Ga to as young as 0.1 Ma (or even younger) can be obtained in a quick and cost-effective manner with a reasonable (~5% at 1σ) uncertainty. [ABSTRACT FROM AUTHOR]

The large-sized Tarangaole uranium deposit and its neighboring Daying and Nalinggou deposits, located in the northeastern margin of the Ordos Basin, constitutes a major uranium resource base in northern China. In order to further clarify the sedimentary material source, uranium source and regional sediment–tectonic setting of the uranium-fed clastic rocks (i.e., Zhiluo Formation(J2z)) in the district, this paper carried out whole-rock geochemistry, heavy minerals composition and in situ U-Pb dating of detrital zircons for sandstones from the lower section of the Zhiluo Formation. The results have shown that the average chemical differentiation index (CIA) for the host rocks is 73.16 and the chemical weathering degree is moderate. Heavy minerals are mainly composed of ilmenite, garnet, chlorpyrite, zircon, pyrite, apatite, hematite, etc. The U-Pb dating of detrital zircon generally indicates three age peaks, i.e., 260~Ma, 1850~Ma and 2450~Ma, respectively. In conclusion, the source rocks may have been formed at active continental margins, e.g., in a continental margin arc environment. The sedimentary materials mainly come from khondalite series, TTGs, granulite, and mafic–ultramafic intrusive rocks distributed among the Daqing–Ula Mountains and adjacent areas, etc. The Late Paleozoic U-rich intermediate and acidic magmatic rocks spreading over the eastern part of the Ula–Daqing and Wolf mountains have provided the main uranium sources for the formation of major U deposits in the northern Ordos Basin. [ABSTRACT FROM AUTHOR]

The thermoelastic properties and thermal expansion of natural single-crystal zircon without detectable radiation damage were determined in the temperature range between 100 and 1650 K on five samples from Cambodia, Sri Lanka, and Tanzania. Up to about 1500 K, the results are in excellent agreement and fully reversible. The average adiabatic elastic stiffness coefficients at room temperature in GPa are c11 = 426.8(6), c12 = 68.1(4), c13 = 152.0(4), c33 = 490.8(9), c44 = 113.1(2), and c66 = 49.0(1). Polycrystalline averaging for the aggregate bulk and shear modulus (Voigt-Reuss-Hill average) yields K = 229.3(4) GPa and G = 109.3(1) GPa. From 293 to 1573 K, the elastic stiffnesses soften almost linearly with the temperature coefficients in MPa/K: dc11/dT = –45.36(7), dc12/dT = –2.03(7), dc13/dT= –9.59(7), dc33/dT = –42.85(12), dc44/dT = –9.60(3), and dc66/dT = –2.19(1). Below room temperature, the behavior of the cij is nonlinear, with decreasing absolute values of the temperature coefficients. Above about 1500 K, a temperature- and time-dependent irreversible elastic stiffening accompanied by an increasing ultrasound dissipation was observed in all samples. These anomalies are interpreted to be the consequence of increased dislocation densities. [ABSTRACT FROM AUTHOR]

Arc-arc amalgamation occurs during the evolution of composite orogens at convergent plate margins and plays a critical role in controlling accretionary patterns and processes. The eastern Junggar terrane in the southern Central Asian Orogenic Belt underwent a long-lived subduction-accretion process in the Paleozoic, but whether and how the Yemaquan and Dananhu-Harlik arcs were amalgamated remain debatable. A systematic U-Pb-Hf-O isotopic study was conducted on zircons from Silurian granitic rocks in the Yemaquan arc. The U-Pb dating results suggest that these rocks were emplaced at 433-422 Ma and inherited abundant 536-435 Ma zircons representing a predominant magmatic episode in the Yemaquan arc. Their positive εHf(t) values and young Hf model ages indicate that the Yemaquan arc is dominated by juvenile basement with significant crustal growth during the Neoproterozoic to early Paleozoic. The variations in zircon Eu/Eu*, εHf(t), and δ18O values reveal that the Yemaquan arc experienced remarkable crustal thickening and remobilization at ca. 450 Ma, similar to the northern Dananhu-Harlik arc, and this was followed by extension that initiated at ca. 420 Ma. These features support the amalgamation of these two arcs occurring ca. 450-420 Ma. Integrated with regional data, we correlated this amalgamation event in the eastern Junggar terrane with the orogenic event in the Chinese Altai terrane, and we propose a middle Paleozoic tectonic evolution model in the eastern Junggar-Altai area from arc assembly to dispersal in association with a transition in accretionary mode. This scenario probably took place as a response to plate reorganization during the breakup of the northern margin of Gondwana. [ABSTRACT FROM AUTHOR]

Unraveling the Paleo-Kuril Arc's origins is key to understanding northwest Pacific tectonics. The Paleo-Kuril Arc is viewed as an intraoceanic arc from trench subduction between the Izanagi and Pacific Plates. Alternatively, several studies suggest the Paleo-Kuril Arc as a continental magmatic arc, hypothesizing the existence of a mid-oceanic ridge and Paleogene subduction, placing the Paleo-Kuril Arc near the Okhotsk Block's southern edge. This study clarifies these hypotheses, previously clouded by limited geochronological data on deposits in the Paleo-Kuril Arc. We conducted U–Pb dating to examine the origins of detrital zircons from the Cretaceous–Paleogene Tokoro and Nemuro Belts of the Paleo-Kuril Arc. Cluster analysis, merging new and existing data, identified two unique detrital zircon age clusters. The abundance of Precambrian zircons in Cretaceous–Paleocene Paleo-Kuril Arc sandstones (Type 1 Cluster) suggests a continental magmatic origin, supporting the ridge subduction model. However, an early Eocene shift to a consistent local volcanic source (Type 2 Cluster) highlights a significant provenance change. This geochronological evidence, indicating a separation from continental sources, calls for further research to decode the simultaneous development of sediment sources in different geological belts, potentially tied to the ridge subduction event. [ABSTRACT FROM AUTHOR]

Late Triassic–Jurassic orogenic and Early Cretaceous epithermal Au deposits are significant producers of Au, Ag, and potentially critical elements (e.g., Te, Se and Sb) in the North Heilongjiang Belt in the Xing'an Block, NE China. However, the preservation mechanism of these Au deposits associated with tectonic evolution is unclear. Here, we conducted zircon U–Pb, sericite Ar–Ar, zircon and apatite (U–Th)/He dating as well as whole‐rock geochemistry in the Xing'an Block. Zircon U–Pb dating shows the ages of 174.1 ± 2.4 Ma for the granodiorite, 169.9 ± 1.6 Ma for the tonalite, 154.0 ± 2.0 Ma for the monzogranite and ca.122 Ma for the diorite. Sericite Ar–Ar dating presents plateau and isochron ages of 163.2 ± 1.8 Ma and 163.4 ± 2.8 Ma. The average apatite (U–Th)/He (AHe) and zircon (U–Th)/He (ZHe) ages from the Jurassic rocks have the ranges of ca. 146–89 Ma and ca. 150–116 Ma and from the Cretaceous are ca. 109–76 Ma and ca. 117–111 Ma, respectively. The Early‐Middle Jurassic intrusions are featured by the tonalite‐trondhjemite‐granodiorite (TTG) rock type. Late Jurassic monzogranite has the geochemical signature of adakitic rocks. The Early Cretaceous granitoids are classified as volcanic arc granites with a part of the Early Cretaceous granodiorite featured by adakitic. These new results reveal five group ages associated with tectonic evolution, Au mineralization and the preservation of the Au deposits. (i) Magmatic events were related to the subduction of the Mongolia‐Okhotsk Ocean during the Early Jurassic (ca. 177–170 Ma) and then the compressional settings with regional deformation (ca. 167–163 Ma). (ii) Thickening crust and orogenic Au mineralization were related to the closure of the Mongolia‐Okhotsk Ocean (ca. 154–145 Ma). (iii) The transformation was from compressional to extensional settings followed by exhumation during the Early Cretaceous (ca. 145–120 Ma), which is the factor of the exhumation of the orogenic Au deposits formed from the Late Triassic to Late Jurassic. (iv) Epithermal Au–Ag mineralization was associated with an extension related to the subduction of the Palaeo‐Pacific Plate (ca. 120–100 Ma). (v) Thermal history shows one thermal event during the Late Cretaceous (ca. 89–76 Ma). The Au deposits have been preserved since the Late Cretaceous. [ABSTRACT FROM AUTHOR]

Direct dating of vertebrate fossils is difficult due to complex postburial diagenetic processes and the often low and heterogeneous concentration of radioisotopes (e.g., U) in fossilized bone material. Here, we demonstrate a novel approach to dating vertebrate fossils via laser ablation–inductively coupled plasma–mass spectrometry U-Pb dating of early diagenetic calcite cements precipitated within bone cavities of a Jurassic sauropod from the Sichuan Basin, South China. Early diagenetic calcite yielded a U-Pb age of 165.3 ± 3.6/5.6 Ma, in agreement with a maximum depositional age of 165.8 ± 1.0 Ma from detrital zircon ages of the surrounding rocks, suggesting that diagenesis occurred shortly after the death of the sauropod. This new age demonstrates that the best-known Jurassic large sauropod faunas in South China are much older than those in North America and Africa, suggesting the geographical isolation of South China. Authigenic apatite U-Pb dating on the fibrolamellar bones from the same sauropod gave a distinctly younger age, indicating more complex U-Pb system behavior, possibly due to U uptake by residual organic matter and recrystallization of apatite after early diagenesis. Our findings demonstrate that U-Pb dating of calcite cements within bone cavities has significant potential for constraining the burial age of vertebrate fossils, which could aid in constructing a more robust temporal framework for the radiation and evolution of vertebrates. [ABSTRACT FROM AUTHOR]

Arc magmas are produced from the mantle wedge, with possible addition of fluids and melts derived from serpentinites and sediments in the subducting slab. Identification of various sources and their relevant contributions to such magmas is challenging; in particular, at continental arcs where crustal assimilation may overprint initial geochemical signatures. This study presents oxygen isotopic compositions of zoned olivine grains from post-caldera basalts and boron contents and isotopes of these basalts and glassy melt inclusions hosted in quartz and clinopyroxene of silicic tuffs in the Toba volcanic system, Indonesia. High-magnesian (≥87 mol% Fo [forsterite]) cores of olivine in the basalts have δ18O values ranging from 5.12‰ to 6.14‰, indicating that the mantle source underneath Toba is variably enriched in 18O. Olivine with <87 mol% Fo has highly variable (4.8-7.2‰), but overall increased, δ18O values, interpreted to reflect assimilation of high δ18O crustal materials during fractional crystallization. Mass balance calculations constrain the overall volume of crustal assimilation for the basalts as ≤13%. The processes responsible for the 18O-enriched basaltic melts are further constrained by boron data that indicate the addition of <0.1 wt% fluids to the mantle, >40% of the fluids being derived from serpentinites and others from altered oceanic crust and sediments. This amount of fluids can increase δ18O of the magma by only ∼0.02‰. Approximately 6-9% sediment-derived melt hybridization in the mantle wedge is further needed to yield basaltic melts with δ18O values in equilibrium with those of the high-Fo olivine cores. The cogenetic silicic tuffs, on the other hand, seem to record a higher proportion of fluid addition dominated by sediment-derived fluids to the mantle source, in addition to crustal assimilation. Our reconnaissance study therefore demonstrates the application of combined B and O isotopes to differentiate between melts and fluids derived from serpentinites and sediments in the subducted slab-an application that can be applied to arc magmas worldwide. [ABSTRACT FROM AUTHOR]

The Wunugetu deposit, a large-scale porphyry copper–molybdenum deposit, is located in the southern Erguna block. Its ore bodies are primarily found within monzogranites, granite porphyries, and biotite monzogranites. Additionally, the deposit contains late-stage intrusive dykes of rhyolitic porphyries. This study examined the deposit's monzogranites and rhyolitic porphyries using lithogeochemistry, zircon U-Pb dating, and Hf isotopic analysis. The main findings include: (1) Zircon U-Pb dating showed that the monzogranites formed around 209.0 ± 1.0 Ma, whereas the rhyolitic porphyries in the northern portion formed around 170.49 ± 0.81 Ma, suggesting magmatic activity in the deposit spanned from the Late Triassic to the Middle Jurassic. (2) The monzogranites exhibited high silicon content (73.16–80.47 wt.%) and relatively low aluminum content (10.98–14.37 wt.%). They are enriched in alkalis (content: 3.42–10.10 wt.%) and deficient in magnesium and sodium, with aluminum saturation indices (A/CNK) ranging from 1.1 to 2.9. In addition, the monzogranites are enriched in large-ion lithophile elements (LILEs) such as Rb, K, and Ba and deficient in high-field-strength elements (HFSEs) like Nb, P, and Ti. (3) The monzogranites have low Zr + Nb + Ce + Y contents of (151.3–298.6 ppm) × 10−6 and 10,000 × Ga/Al ratios varying between 1.20 and 2.33, suggesting that they are characteristic of I-type granites. (4) Positive zircon εHf(t) values ranging from +0.3 to +7.6 in both rhyolitic porphyry and monzogranite samples, increasing with younger emplacement ages, imply that the deposit's rocks originated from magmatic mixing between mantle-derived mafic magmas and remelts of the juvenile crust. Considering these results and the regional geological evolution, this study proposes that the Wunugetu deposit was formed in an active continental margin setting and was influenced by the Late Triassic–Middle Jurassic southeastward subduction of the Mongol-Okhotsk Ocean. [ABSTRACT FROM AUTHOR]

It has been accepted that granitoids of the Irizar unit in the Central Victoria Land (Antarctica), as an important part of the Granite Harbour Intrusives, were formed in a post-collisional setting during the Ross orogeny along the margin of east Gondwana. However, the emplacement ages of the Irizar unit remain poorly constrained, making it difficult to form a more complete picture of the geodynamic evolution of the Ross orogen and its counterpart (Delamerian orogen) in southeast Australia. In this work, four syenogranite samples from the Irizar unit were chosen for SHRIMP zircon U-Pb dating, which yielded ages of 507.8–489.7 Ma. The new geochronological data indicate that the post-collisional extension in the Central Victoria Land had begun by ~508 Ma, much earlier than previously thought (i.e., 490–480 Ma). Integrated with U-Pb ages for Early Paleozoic granitoids from the literature, the Ross–Delamerian orogen shows that the post-collisional granitic magmatism initiated at ~515 Ma in the Central Transantarctic Mountains and northward systematically decreased to ~508 Ma in the Victoria Land, and then to ~487 Ma in southeast Australia. This can be explained well by the propagating northward transition from pre- and syn-collisional compression to post-collisional extension. [ABSTRACT FROM AUTHOR]

The intensive variables, geochemical, mineralogical, and petrogenetic constraints of the Iberian peraluminous rare metal granites (RMGs), many of them unknown, are presented. The mineral chemistry of ore and gangue minerals, whole rock analyses, geothermobarometry, melt water and phosphorus contents, mass balance, and Rayleigh modeling were performed to achieve these objectives. These procedures allow us to distinguish two main contrasting granitic types: Nb-Ta-rich and Nb-Ta-poor granites. The former have lower crystallization temperatures, higher water contents, and lower emplacement pressures than Nb-Ta-poor granites. Nb-Ta-rich granites also have higher fluoride contents, strong fractionation into geochemical twins, higher Na contents, and different evolutionary trends. At the deposit scale, the fractional crystallization of micas properly explains the variation in the Ta/Nb ratio in both Nb-Ta-poor and Nb-Ta-rich RMGs, although in higher-grade granites, the variation is not as clear due to the action of fluids. Fluid phase separation processes especially occurred in the Nb-Ta rich granites, thus transporting halogens and metals that increased the grades in the top and sometimes in the core of granites. Gas-driven filter pressing processes facilitated the migration of fluid and melt near solidus melt in Nb-Ta-rich granites. The geochemical signature of the Iberian rare metal granites mainly follows the trends of two-mica granites and P-rich cordierite granites, but also of granodiorites. [ABSTRACT FROM AUTHOR]

The Bilong Co oil shale is one of the most significant source rocks in the Mesozoic Qiangtang Basin (Northern Tibet); however, its absolute chronology remains controversial. In this study, in situ carbonate U–Pb isotope dating analysis was carried out for the first time. Detailed field geological investigations yielded some age-diagnostic ammonites, enabling a re-evaluation of the stratigraphic age of the Bilong Co oil shale. A total of 61 spots of U–Pb isotope dating from the middle part of the Bilong Co oil shale section suggests an average age of 181 ± 13 Ma. Elemental geochemistry and diagenetic analysis indicate that the proposed age represents the early deposition of the calcite, and the oil shale was deposited during the Early Jurassic time. This estimated age is further supported by the newly discovered ammonite assemblage of Hildoceratidae–Tiltoniceras sp. at the top part of the oil shale section, which confirms the deposition of the oil shale during the Toarcian age of the late Early Jurassic. Consequently, the Bilong Co oil shale can be assigned to the Quse Formation, which is attributed to the Lower Jurassic rather than the Middle Jurassic. The re-assessment of the stratigraphic age of the Bilong Co oil shale is of great significance for regional evaluation and exploration activities of hydrocarbon source rock layers in the Qiangtang Basin as well as for global stratigraphic correlation of the late Early Jurassic Toarcian oceanic anoxic event. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries represent a promising class of next-generation rechargeable energy storage technologies, primarily because of their high-capacity sulfur cathode, reversible battery chemistry, low toxicity, and cost-effectiveness. However, they lack a tailored cell material and configuration for enhancing their high electrochemical utilization and stability. This study introduces a cross-disciplinary concept involving cost-efficient cement and sulfur to prepare a cement/sulfur energy storage material. Although cement has low conductivity and porosity, our findings demonstrate that its robust polysulfide adsorption capability is beneficial in the design of a cathode composite. The cathode composite attains enhanced cell fabrication parameters, featuring a high sulfur content and loading of 80 wt% and 6.4 mg cm−2, respectively. The resulting cell with the cement/sulfur cathode composite exhibits high active-material retention and utilization, resulting in a high charge storage capacity of 1189 mA∙h g−1, high rate performance across C/20 to C/3 rates, and an extended lifespan of 200 cycles. These attributes contribute to excellent cell performance values, demonstrating areal capacities ranging from 4.59 to 7.61 mA∙h cm−2, an energy density spanning 9.63 to 15.98 mW∙h cm−2, and gravimetric capacities between 573 and 951 mA∙h g−1 per electrode. Therefore, this study pioneers a new approach in lithium–sulfur battery research, opting for a nonporous material with robust polysulfide adsorption capabilities, namely cement. It effectively showcases the potential of the resulting cement/sulfur cathode composite to enhance fabrication feasibility, cell fabrication parameters, and cell performance values. [ABSTRACT FROM AUTHOR]

A large amount of distal skarn Pb–Zn deposits without any causative intrusions exposed have been discovered along the eastern Nyainqêntanglha metallogenic belt (NMB) in the Gangdese region, Tibet, China. As a typical distal skarn Pb–Zn deposit in the east of NMB, the Mengya'a deposit is adjacent to the Longmala Pb–Zn ± Cu ± Fe deposit. However, the linkage between these two deposits is not unclear due to the chaotic dating results. In situ Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA‐ICP‐MS) U–Pb dating of reddish‐brown and yellow‐green garnet from Mengya'a yielded lower intersect ages of 53.6 ± 3.1 and 52.4 ± 4.4 Ma, respectively, indicating that Pb–Zn mineralization took place during the main collision stage of the India–Asia plates. The δDSMOW values of garnet, quartz and calcite vary from −148.4‰ to −140.4‰, −123.5‰ to −115.3‰ and −127.9‰ to −121.3‰, with the δ18OH2O values ranging from 5.8‰ to 6.6‰, 0.4‰ to 3.7‰ and 1.0‰ to 1.7‰, respectively. The δ13CV‐PDB and δ18OSMOW values of calcite range from −8.2‰ to −4.7‰ and 9.8‰ to 18.6‰, respectively. These C–H–O isotopic compositions of hydrothermal minerals indicate that the ore‐forming fluids were initially derived from the magmatic water with progressive input of meteoric water from the prograde stage to the retrograde stage. The 87Sr/86Sr(53 Ma) ratios of sphalerite (0.72321–0.73474) are consistent with those of Ando gneiss in the Lhasa‐Golmud area, indicating that the basement gneiss makes a great contribution for the source of ore‐forming materials. The newly obtained garnet U–Pb ages at Mengya'a are consistent with those of mineralization and causative intrusion in the Longmala Pb–Zn ± Fe ± Cu deposit, suggesting that the Mengya'a and Longmala deposits constitute an integrated distal skarn‐type system. This proposed hypothesis suggests that the Fe–Cu ± Pb ± Zn mineralization within the contact zone should focus on the locations beneath the identified Pb–Zn orebodies at Longmala and Pb‐21 orebody at Mengya'a. [ABSTRACT FROM AUTHOR]

The Lamasu deposit is the first large copper (Cu) deposit with ~0.6 Mt Cu reserve in the Chinese Western Tianshan Orogen (NW China). The Cu orebodies are mainly hosted in the exoskarn of the Proterozoic Kusongmuqieke Group. Now, the metallogenic mechanism of newly discovered skarn Cu orebodies (0.5 Mt Cu) remains poorly constrained. In this study, we conducted LA‐ICP‐MS U–Pb isotope dating, EPMA and LA‐ICP‐MS geochemical analyses on different generations of garnet from Lamasu to elucidate the magmatic hydrothermal evolution and its timing. Garnets from the Lamasu exoskarn can be divided into three types: reddish‐brown coarse‐grained Grt‐I, light brown fine‐grained Grt‐II and yellowish‐green heterogranular Grt‐III, with U–Pb age of 389.1 ± 2.0 Ma, 387.1 ± 1.8 Ma and 387.0 ± 2.3 Ma, respectively. These dates represent the oldest Cu mineralization age in the Chinese Western Tianshan, coeval with the Middle Devonian subduction of the North Tianshan oceanic plate. Grt‐I to Grt‐III particles are mainly andradite with minor grossularite, and they have different REE compositions. The Grt‐I has total REE contents (∑REE) of 101.47 to 262.87 ppm, with steeply right‐inclining REE distribution patterns (LREE/HREE of 3.81 to 68.50) and positive Eu anomaly. The Grt‐II core has ∑REE of 163.49–249.52 ppm, LREE/HREE of 2.00–4.71, and negative Eu anomaly. The Grt‐II rim has ∑REE of 46.34–99.99 ppm, with LREE/HREE of 18.06–177.23, and positive Eu anomaly. The ∑REE of Grt‐III range from 31.71 to 219.02 ppm, with flat REE distribution pattern and positive Eu anomaly, and the LREE/HREE ranges from 2.16 to 9.07. These garnets have similar trace element compositions, featured by LILE‐depletions (e.g., Rb, Ba and Sr) and HFSE enrichments (e.g., Th, U, Nb and Ce). Micro‐texture and geochemical composition of garnets indicate that the Lamasu magmatic hydrothermal system could have changed from an open to a closed environment, and from infiltration metasomatism to diffusive metasomatism, which formed Grt‐I, Grt‐II and Grt‐III successively. These garnets generally formed in a relatively oxidized fluid environment, which inhibited early sulphide precipitation and favoured for Cu enrichment during the ore fluid evolution. [ABSTRACT FROM AUTHOR]

Silicic magma reservoirs are responsible for producing the largest explosive eruptions in the geologic record. Petrologic and geochronological data provide evidence for these systems spending substantial periods of time (104–105 yrs) within the upper crust prior to eruption; however, the long-term thermochemical evolution of these systems is not fully understood, as existing petrologic data make it challenging to quantify the time interval a magmatic system has spent at certain temperatures, or its "thermal history". Here, we investigate the 74 ka Youngest Toba Tuff (YTT), one of the largest explosive eruptions in the geologic record, to better constrain the long-term thermal evolution of its magmatic system. We combine forward models of Sr diffusion in plagioclase and hornblende, mineral thermometry, and pre-existing trace-element evolution models to quantify the thermochemical evolution of the YTT magmatic system. We find that plagioclase crystals record decades to centuries of storage at temperatures > ∼ 750 ∘ C, while hornblende records up to 6200 years at the same temperatures. Hornblende crystallizes at temperatures around 820 ∘ C and adjusting our diffusion modeling to this temperature results in no more than 900 years at initial crystallization conditions. Combined with previous trace-element modeling work, these results indicate that although there was chemical diversity for long durations in the YTT magma system sufficient to produce unique composition eruptive products, the entire system was experiencing a relatively similar thermal history that did not allow for large bodies of eruptible magma to be present for long periods ( > > 102–103 years). Rather, we suggest that magmas within the YTT magmatic system were stored for long durations at thermal conditions where they were uneruptible and only remobilized within a few centuries prior to eruption. [ABSTRACT FROM AUTHOR]

Scheelite, one kind of common REE-rich and U-bearing hydrothermal mineral, is extensively developed in various types of gold deposits, which can be used to record nature and timing of metallogenesis. The Zhaishang Carlin-like gold deposit in the Qinling Orogen is a giant Au deposit, hosting 127t of Au @ 2.67 g/t with economic concentrations of tungsten and antimony. The study reports two types of scheelite based on the characteristics of petrography and geochemistry. Sch A shows significant oscillatory zoning with dark gray cathodoluminescence (CL) response, whereas Sch B displays patchy textures with brighter CL response. Systematic LA-ICP-MS U–Pb dating of Sch A and Sch B yields ages of 227.1 ± 3.2 Ma and 226.2 ± 6.9 Ma, respectively. The new dates, constraining the Zhaishang Au–W mineralization to ~ 227Ma, coincide well with the western Qinling magmatism, metallogenic and tectonic events. There are significant variations in concentration, the Sch A has low REE content (mean = 41.3 ppm), negative Eu-anomaly with slightly positive Ce-anomaly, whereas Sch B, with small negative or positive Eu-anomaly, has higher REE content (mean = 247 ppm) and higher positive Ce-anomaly. The positive correlation of EuN and EuN* records oxidizing condition during the whole W mineralization event. Additionally, Sch B intergrown with selenides with an increase in the Ce-anomaly supports that the latter has higher oxygen fugacity environment. The Sr isotope signature for scheelite supports that ore-forming metals mostly inherited the host rock component, while the proportion of magma-derived Sr increased in the Sch B. Fluid–rock interactions co-precipitated Au and W caused by the release of Fe and Ca cations and the increase of pH. The study highlights that scheelite as a recorder can help in deciphering the nature and timing of metallogenesis of the studied Au–Sb–W deposit, and thus other similar Au–W deposits. [ABSTRACT FROM AUTHOR]

The results of U‒Pb (ID-TIMS) geochronological studies of garnet from iron-bearing skarns of the Shalym deposit (Kondoma ore field, Gornaya Shoriya) are presented. Our data are the first direct estimation of the age of the formation of the iron deposit of the Kondoma ore field (499 ± 1 Ma). The formation of this deposit is related to the Middle to Late Cambrian subalkaline magmatism, which hasn't previously been recognized within the Gornaya Shoriya fold areas (the western part of the Altai–Sayan fold area). [ABSTRACT FROM AUTHOR]

By pyrolyzing phosphomolybdic acid-modified Fe-doped ZIF-8 precursor, Fe nanoparticles with Mo and N co-doped carbon frameworks (Fe-NP/MNCF) was created, and the catalysts were intended to be bifunctional ORR and CO 2 RR catalysts. [Display omitted] Metal-organic frameworks (MOF) derived carbon materials are considered to be excellent conductive mass transfer substrates, and the large specific surface area provides a favorable platform for loading metal nanoparticles. Tuning the coordination of metals through polyacid doping to change the MOF structure and specific surface area is an advanced strategy for designing catalysts. Modification of Fe-doped ZIF-8 pre-curing by pyrolysis of phosphomolybdic acid hydrate (PMo), Fe nanoparticles confined by Mo and N co-doped carbon frameworks (Fe-NP/MNCF) were fabricated, and the impact of PMo doping on the shape and functionality of the catalysts was investigated. The Zn-air battery (ZAB) driven CO 2 electrolysis was realized by using Fe-NP/MNCF, which was used as bifunctional oxygen reduction reaction (ORR) and carbon dioxide reduction reaction (CO 2 RR) catalysts. The results show that the half-wave potential (E 1/2) of Fe-NP/MNCF is 0.89 V, and the limiting diffused current density (j L) is 6.4 mA cm−2. The ZAB constructed by Fe-NP/MNCF shows a high specific capacity of 794.8 mAh g Zn −1, a high open-circuit voltage (OCV) of 1.475 V, and a high power density of 111.6 mW cm−2. Fe-NP/MNCF exhibited efficient CO 2 RR performance with high CO Faraday efficiency (FE CO) of 87.5 % and current density for the generation of carbon dioxide (j CO) of 10 mA cm−2 at −0.9 V vs RHE. ZAB-driven CO 2 RR had strong catalytic stability. These findings provide new methods and techniques for the preparation of advanced carbon-based catalysts from MOFs. [ABSTRACT FROM AUTHOR]

Cenozoic dolomitization of reefal carbonates has been widely found on many tropical islands worldwide. However, most ages and geochemical data obtained from bulk samples prevent a clear understanding of the previous complex diagenetic processes of these island dolostones due to a lack of in situ age and fluid composition. In this study, one deep borehole penetrated Cenozoic carbonates on Meiji Island in the southern South China Sea and massive dolostones with thicknesses over 400 m were uncovered. The in situ U–Pb geochronology and elemental analysis were conducted on the lower Nanwan Formation (upper Miocene) comprising undolomitized calcite (bioclast), replacive dolomite, and dolomite cement. Strontium isotope ages and U–Pb dates show that the penecontemporaneous replacive dolomitization occurred at 11.0–8.5 Ma, close to the deposition of precursor limestone. The dolomite cement precipitated at 8.5–6.0 Ma. In situ elemental analyses indicate that the formation of replacive dolomite and dolomite cement in the Nanwan Formation was probably controlled by seawater. The higher Mg/Ca ratio and lower Mn and Sr contents in dolomite cements show that their fluid underwent more evaporation. The dolomite content is positively related to the porosity of reefal limestones in the Nanwan Formation, suggesting that primary voids play an important role in fluid transportation during following dolomitization. Coralline algae and lime mud with algal fragments are beneficial for the rapid nucleation of dolomite. This study demonstrates that in situ elemental analysis using laser ablation has great potential for identifying the source of multistage dolomitizing fluids and can help refine the existing dolomitization model of isolated atolls. [ABSTRACT FROM AUTHOR]

Granulite facies rocks provide important keys to evaluating collisional metamorphism in orogenic belts. The mafic granulites of Baoding in the Fuping Complex of the North China Craton occur within the Trans-North China Orogen (TNCO), a major Paleoproterozoic collisional orogen. Here, we present results from detailed investigations on newly discovered garnet pyroxenite, garnet two-pyroxene granulite, and garnet-bearing-plagioclase amphibolite using petrographic, mineralogical, geochemical, and zircon U-Pb dating methods. Our results show that the Fuping Complex metamorphic evolution in this study evolved in four stages: prograde (M1), high-pressure granulite facies (M2), granulite facies (M3), and retrograde (M4) stages. The mineral assemblage of the prograde stage (M1) consists of Amp + Pl + Q within garnet cores. The mineral assemblage of high-pressure granulite facies at the peak stage (M2) consists of Gt + Cpx + Pl + Q ± Amp, forming the garnet pyroxenite. The granulite facies stage M3 is characterized by the occurrence of orthopyroxene, with a mineral assemblage of Gt + Cpx + Opx + Amp+ Pl + Q. The early retrograde stage M4-1 includes clinopyroxenes scattered inside amphiboles, following the breakdown of garnet and clinopyroxene. The mineral assemblage of this stage comprises Amp + Pl + Q + Ilm ± Cpx. Later, in the late retrograde stage M4-2, the composition of amphiboles changed to actinolite, and epidote and chlorite started to appear in the matrix. Traditional geothermobarometry yielded P-T conditions of 700~706 °C and 6.0~6.2 kbar for prograde stage M1, 854~920 °C and 13.0~13.8 kbar for high-pressure granulite facies stage M2, 912~939 °C and 8.1~9.9 kbar for M3, 661~784 °C and 3.1~4.4 kbar for M4-1, and 637~638 °C, 1.1~1.3 kbar for M4-2, along a clockwise P-T path with a nearly isothermal decompression (ITD) and slight heating. Zircon LA-ICP-MS U-Pb dating constrains the timing of the high-pressure granulite facies metamorphic event to be between 1.83 and 1.86 Ga. Geochemical features suggest that the protoliths of the high-pressure granulites may have formed in an island arc environment within a convergent margin setting. Together with results from previous studies, our data suggest that the ~1.85 Ga metamorphic age recorded in the Fuping Complex represents a regional metamorphism in the TNCO, associated with the subduction–collision and assembly of the Eastern and Western Blocks of the NCC. [ABSTRACT FROM AUTHOR]

Modified magnetite and hydrothermal apatite in banded iron formations (BIFs) are ideal minerals for studying hydrothermal and metamorphic processes and are applied to linking with high-grade Fe mineralization and metamorphism in iron deposits hosted by BIFs. In this study, we have investigated the geochemical composition of modified magnetite and hydrothermal apatite and in situ U-Pb geochronology on apatite from the Huogezhuang BIF-hosted Fe deposit in northeastern China. The magnetite in metamorphosed BIF is modified, locally fragmented, and forms millimeter- to micrometer-scale bands. The apatite is present surrounding or intergrowing with magnetite, has corroded surfaces, and contains irregular impurities and fluid inclusions, indicating that it has been partly hydrothermally altered. Original element compositions (e.g., Fe, Al, Ti, K, Mg, and Mn) of magnetite in BIFs have been modified during high-grade Fe mineralization and retrogressive metamorphism with temperature reduction and addition of acids. The hydrothermally altered apatite has been relatively reduced in the contents of Ca, P, F, La, Ce, Nd, δCe, δEu, and total REEs compared to non-altered apatite. The magnetite and apatite in low-grade BIFs are poorer in FeOT than those from the high-grade Fe ores, indicating that Fe is remobilized during the transition from BIFs to high-grade Fe ores. The magnetite and apatite in high-grade Fe ores are overgrown by greenschist-facies minerals formed during retrograde metamorphism, suggesting that the high-grade Fe mineralization may be related to retrogressive metamorphism. In situ U-Pb geochronology of apatite intergrown with magnetite and zircon LA-ICP-MS U-Pb dating at Huogezhuang deposit reveals that the BIF-hosted magnetite was altered and remobilized at ca. 1950–1900 Ma, and deposition of the BIF began during the Late Neoarchean. The changes of elements in the modified magnetite and diferent geochemical compositions of the altered and unaltered apatite confirm that the modified magnetite and hydrothermal apatite can be efective in tracing high-grade Fe mineralization and retrogressive metamorphism in BIFs. [ABSTRACT FROM AUTHOR]

This study focuses on the hydrothermal synthesis of Bi(Ti x Mn (1-x))O 3 (x = 0.3–0.9) perovskite nanorods on fluorine-doped tin oxide glass substrates and investigates the influence of Ti4+ on their morphological, structural, optical properties, and photocatalytic behavior. The high-resolution XPS spectra results have proved that Ti has been properly substituted into the Bi(Ti x Mn (1-x))O 3 nanorods. The characterization of morphology reveals a decrease in average diameter from 222 to 115 nm as the Ti concentration increases, while the band-gap energy experiences a slight reduction from 3.158 to 3.132 eV. X-ray and Raman spectroscopy analyses of the Bi(Ti x Mn (1-x))O 3 nanorods indicate that Ti ions substitute not only Mn3+ but also Bi3+ ions, leading to structural distortions in the crystal lattice. Moreover, the Bi(Ti x Mn (1-x))O 3 systems demonstrate enhanced photocurrent densities at 1.5 V potential, ranging from 3.19 to 5.54 mA/cm2, as the Ti concentration increases. This enhancement can be attributed to the combined effects of increased surface area, accelerating electron transfer at the interface of the electrode, and decreased optical band-gap energy. It is anticipated that this novel system will pave the way for further advancements in the field of photocatalytic water splitting and solar energy conversion applications. [ABSTRACT FROM AUTHOR]

In this study, the plasma torch is utilized for the preparation of highly pure ZrO 2 from zircon (ZrSiO 4). The incorporation of H 2 into the discharge gas Ar improves the plasma physical parameters and serves as a reducing agent to promote the irreversibility of the pyrolysis reaction of ZrSiO 4. ZrSiO 4 powder is fed internally into a DC arc plasma torch through a powder feeder device. The DC torch generates thermal plasma that can fully heat all the ZrSiO 4 within a short period for pyrolysis, extraction, and separation, eventually producing high-purity ZrO 2. According to the results, the addition of H 2 to the working gas increases the material temperature in the flame by increasing the plasma temperature, thereby promoting the pyrolysis of ZrSiO 4. The temperature of the material is 2500–2600 °C, which is higher than the boiling point of the pyrolysis product SiO 2 while maintaining the high melting points of ZrSiO 4 and ZrO 2. Furthermore, H 2 plasma acts as a reducing agent in the pyrolysis reaction, where it combines with the O of the product to prevent the reversibility of the pyrolysis reaction of ZrSiO 4 and retains only ZrO 2. [ABSTRACT FROM AUTHOR]

Large-scale rock formations, referred to as "rockmasses", consist of intact rock separated by pre-existing discontinuities (i.e., joints). The mechanical behavior of rockmasses is difficult to directly test in the laboratory due to the required specimen scale. Instead, Synthetic Rockmass Modeling (SRM) is often used to simulate field-scale rockmass behavior. SRM requires a calibrated discrete element model (DEM) of intact rock combined with a Discrete Fracture Network (DFN). While the SRM concept has been informally determined to provide reasonable results based on practitioner experience, detailed and peer-reviewed validation is lacking. The goal of this study was to evaluate the predictive capabilities of the SRM method. Previously available data on intact and rockmass analog laboratory specimens of Blanco Mera granite containing DFNs with two joint sets were used as a basis for the SRM created in this study. Specifically, the intact DEM was a Bonded Block Model (BBM), generated to match the grain structure and composition of Blanco Mera granite and the model's input parameters were calibrated so that the behavior of the BBM matched that of the intact laboratory specimens. The predictive capabilities of the model were evaluated by recreating the DFN from the jointed laboratory specimens within the intact BBM and comparing the behavior of the jointed models back to the jointed laboratory specimens, which has not been previously studied in the literature. The BBM was found capable of approximately predicting the behavior of rockmass analog specimens containing a pre-existing DFN without further calibration, which shows potential for the use of SRM in both industry and academia. Specifically, the BBM predicted the strength, dilatancy, and microfracturing behavior of the jointed laboratory specimens. [ABSTRACT FROM AUTHOR]

The Ilkurlka structure is an ~12 km diameter buried circular aeromagnetic anomaly within the Officer Basin in Western Australia. Prior studies postulated a range of origins, including meteorite impact. We report the presence of pervasive deformation in the first drill cores from the structure. Brecciated sandstone and siltstone contain arrays of quartz grains with concussion fractures and rare shocked quartz grains with planar deformation features (PDF). Universal stage measurements of two quartz grains reveal one grain with PDF parallel to (0001) orientation and three PDF sets parallel to 101¯3. A second grain contains three PDF sets parallel to 101¯3 and one set parallel to 101¯4. The shocked grains are interpreted to have formed in situ, rather than representing transported detrital shocked grains. These results suggest local shock compression of at least 10 GPa; however, preservation of primary porosity and overall paucity of shocked grains may indicate lower mean shock pressures. (U‐Th)/He dating of 58 apatite grains from four samples across both cores shows a dominant age population at ~265 Ma and a minor age population at ~135 Ma. These dates overlap with regional events and thus do not provide an unambiguous impact age. An upper Carboniferous to lower Permian maximum impact age is provisionally proposed based on inferred missing target rock stratigraphy. [ABSTRACT FROM AUTHOR]

This study focuses on the hydrothermal synthesis of Bi(Ti x Mn (1-x))O 3 (x = 0.3–0.9) perovskite nanorods on fluorine-doped tin oxide glass substrates and investigates the influence of Ti4+ on their morphological, structural, optical properties, and photocatalytic behavior. The high-resolution XPS spectra results have proved that Ti has been properly substituted into the Bi(Ti x Mn (1-x))O 3 nanorods. The characterization of morphology reveals a decrease in average diameter from 222 to 115 nm as the Ti concentration increases, while the band-gap energy experiences a slight reduction from 3.158 to 3.132 eV. X-ray and Raman spectroscopy analyses of the Bi(Ti x Mn (1-x))O 3 nanorods indicate that Ti ions substitute not only Mn3+ but also Bi3+ ions, leading to structural distortions in the crystal lattice. Moreover, the Bi(Ti x Mn (1-x))O 3 systems demonstrate enhanced photocurrent densities at 1.5 V potential, ranging from 3.19 to 5.54 mA/cm2, as the Ti concentration increases. This enhancement can be attributed to the combined effects of increased surface area, accelerating electron transfer at the interface of the electrode, and decreased optical band-gap energy. It is anticipated that this novel system will pave the way for further advancements in the field of photocatalytic water splitting and solar energy conversion applications. [ABSTRACT FROM AUTHOR]

In this study, the plasma torch is utilized for the preparation of highly pure ZrO 2 from zircon (ZrSiO 4). The incorporation of H 2 into the discharge gas Ar improves the plasma physical parameters and serves as a reducing agent to promote the irreversibility of the pyrolysis reaction of ZrSiO 4. ZrSiO 4 powder is fed internally into a DC arc plasma torch through a powder feeder device. The DC torch generates thermal plasma that can fully heat all the ZrSiO 4 within a short period for pyrolysis, extraction, and separation, eventually producing high-purity ZrO 2. According to the results, the addition of H 2 to the working gas increases the material temperature in the flame by increasing the plasma temperature, thereby promoting the pyrolysis of ZrSiO 4. The temperature of the material is 2500–2600 °C, which is higher than the boiling point of the pyrolysis product SiO 2 while maintaining the high melting points of ZrSiO 4 and ZrO 2. Furthermore, H 2 plasma acts as a reducing agent in the pyrolysis reaction, where it combines with the O of the product to prevent the reversibility of the pyrolysis reaction of ZrSiO 4 and retains only ZrO 2. [ABSTRACT FROM AUTHOR]

The Kuznetsk Basin (Kuzbass) is one of the largest coal basins in Siberia and a reference area for the ancient Angaraland continent. The proximity of the Kuzbass and Siberian Platform caused their biotic similarities in the Late Palaeozoic. However, due to biota endemism, the Kuzbass Upper Palaeozoic does not correlate directly with the International Chronostratigraphic Chart (ICC). This paper discusses radioisotopic (CA-ID-TIMS) dating of zircons from a volcanic tuff located in the Starokuznetsk Formation (Fm). This level matches the interval of the Balakhonka/Kolchugino (B/K) floral change in Kuzbass, i.e., the gradual replacement of cordaitoid-dominated wet forests (Balakhonka flora) with more arid fern–pteridosperm–cordaitoid assemblages (Kolchugino flora). New age (276.9 ± 0.4 Ma) directly correlates the Starokuznetsk Fm with the Upper Kungurian of the ICC. We compared the Kuzbass data with data of the Western Verkhoyanie, where Middle Permian ammonoids (Sverdrupites assemblage) occur in strata recording the B/K floral change. The available (ICC) and new datings indicate the lag between the B/K floral change in low (Kuzbass) and high (Verkhoyanie) latitudes of Angaraland. The B/K floral change in the Kuzbass began in the early Late Kungurian and was completed by the end of this age. In contrast, the B/K floral change in Verkhoyanie began at the end of the Late Kungurian and was completed in the Late Wordian. The delay in the floral changes at different latitudes of Angaraland suggests that existing interregional correlations need further improvement. [ABSTRACT FROM AUTHOR]

Permian intermediate–felsic igneous rocks, widely distributed in the southern Beishan orogen, provide crucial constraints on the geodynamic process of the late Paleozoic Paleo-Asian Ocean. New zircon U–Pb dating using LA–ICP–MS determines the age of the northern Qingshan diorites, the Heishantou quartz diorites, and the southern Qingshan biotite granodiorites at 300 Ma, 294 Ma, and 291–286 Ma, respectively. Their whole-rock compositions exhibit arc-like geochemical features. Moreover, their zircon trace elements show the characteristics of continental arc zircons. The diorites, characterized by low SiO2, high MgO with Mg# (50–52), and low Cr, Co, and Ni, display enrichment in Sr-Nd-Hf isotopes (87Sr/86Sr = 0.7060 to 0.7061; ℇNd(t) = −1.4 to −1.7; ℇHf(t) = −4.7 to −0.6), originating from the fractionation process of magma derived from the enriched mantle. The quartz diorites show moderate SiO2 and variable MgO (2.75–3.84 wt%) and exhibit enrichment in Sr-Nd (87Sr/86Sr = 0.7048–0.7050; ℇNd(t) = −1.5–+0.9) and depletion in zircon Hf isotopes (ℇHf(t) = 3.8 to 7.8). Combined with their high Y (20.0–21.0 ppm) and low (La/Yb)N (6.0 to 17.2), we conclude that they originated from the juvenile lower crust previously influenced by oceanic sediments, with the input of enriched mantle-derived materials. The biotite granodiorites display low A/CNK (0.91–0.97), 10000*Ga/Al (1.8–1.9), and Ti-in-zircon temperatures (average 711 °C), indicating that they are I-type granitoids. These rocks show enrichment in Sr-Nd isotopes (87Sr/86Sr = 0.7054 to 0.7061; ℇNd(t) = −2.0 to −1.6) and many variable zircon Hf isotopes (ℇHf(t) = −2.3 to +4.5). Geochemical studies indicate that they originate from the mixing of magmas derived from the enriched mantle and preexisting juvenile lower crust. All these data imply the existence of oceanic subduction in southern Beishan during the early Permian. Integrating these results with previous studies, it is inferred that the retreating subduction of the Liuyuan Ocean contributed to early Permian intermediate–felsic rocks becoming widespread in the Shibanshan unit, the southernmost part of the Beishan orogen, and also why the Paleo-Asian Ocean in southern Beishan did not close during the early Permian. [ABSTRACT FROM AUTHOR]

The influence of the paleo-Tethys or paleo-Pacific oceanic plate subduction on Early Triassic South China has long been debated. We have studied the zircon U-Th-Hf isotopes, trace elements, and whole-rock geochemistry of Early Triassic peraluminous granitoids in the Qinzhou Bay area, South China Block. LA–ICP–MS zircon U–Pb dating has revealed the Jiuzhou granodiorites and Dasi-Taima granite porphyries formed between 248.32 ± 0.98 and 246.6 ± 1.1 Ma. These rocks are characterized by high K2O and Al2O3, and low MgO, CaO, and P2O5 contents with A/CNK = 1.06–1.17, showing high-K calc-alkaline S-type affinities. The Early Triassic intrusive rocks and adjacent silicic volcanic rocks in the Qinzhou Bay area were found to be comagmatic and derived from a common magma pool, detached in an undifferentiated melt instead of indicating remarkable crystal—melt separation. Although the analyzed granitoids have highly enriched zircon Hf isotopic compositions (εHf(t) = −23.9 to −7.8), they cannot originate solely from metasedimentary protoliths. Source discrimination indicators have revealed enriched lithospheric mantle-derived magma was also an endmember component of the S-type silicic magma, which provided a heat source for the crustal anatectic melting as well. We inferred the studied Early Triassic granitoids formed under the paleo-Tethys tectonic regime before the collision of South China and Indochina blocks, as the oceanic plate subduction would have created an extensional setting which further caused the mantle-derived upwelling and volcanic eruption. [ABSTRACT FROM AUTHOR]

The Early Cretaceous Weideshan granites are associated with large-scale Au and polymetallic Cu-Mo-Pb-Zn mineralization. To investigate the petrogenesis of the Weideshan granite and constrain its tectonic setting during the Early Cretaceous, we conducted a zircon U-Pb-Hf isotope and whole-rock geochemical and Sr-Nd isotopic study of the granite. In situ zircon U-Pb dating of three granite samples yielded Early Cretaceous ages of 112.83 ± 0.80, 112.64 ± 0.91, and 111.82 ± 0.78 Ma. The samples had high-K calc-alkaline compositions and were enriched in the light rare earth and large-ion lithophile elements (e.g., K, Rb, Ba, Th, and U) and depleted in high-field-strength elements (e.g., Nb, Ti, and P). The samples had small negative Eu anomalies and initial 87Sr/86Sr and εNd(t) values of 0.70853–0.71029 and –18 to –14, respectively. The zircon εHf(t) values varied between −16 and −12, with corresponding two-stage model ages (tDM2) of 2180–2000 Ma. These characteristics indicated that the Weideshan pluton was formed in a back-arc extensional environment caused by subduction of the Paleo-Pacific Plate toward the Asian continent during the early Cretaceous. The magma was generated by crust–mantle interaction during lithospheric thinning. The diagenetic age of the Weideshan granites was the same as the formation age of gold and polymetallic ores in the Jiaodong area. The extensive fluid circulation induced by the magma emplacement may be the main source of ore-forming materials for the gold and polymetallic Cu-Mo-Pb-Zn deposits. [ABSTRACT FROM AUTHOR]

In this study, we design and test a current controller for a source of thermionic electron emission operating in an ionization vacuum gauge. We use a precise and controlled source of current to transfer the emission current from the anode, which has a high potential in the circuit, to the cathode with a low potential. This eliminates the need for galvanic isolation or sources of floating voltage, which introduce noise to the system, for supplying the cathode and the anode. We show that this has a limited effect in terms of changes in the residual gas pressure on the emission current in the range from 10−4 to 10−2 Pa. The temporal stability of the emission current was determined for reference values ranging from 1 to 4 mA for both 10-min and 2-h periods, and it was found to be lower than 6 ppm. The proposed controller can be used in apparatus to measure electron impact-induced gas ionization. [ABSTRACT FROM AUTHOR]

A rostrum fragment of a representative of the Toarcian–Early Aalenian (the latest Early Jurassic–the earliest Middle Jurassic) belemnites Arcobelus cf. krimholzi (Sachs, 1970) was found for the first time in kimberlites of the Obnazhennaya pipe of the Kuoika kimberlite field (northeastern Siberian Platform, Olenek Uplift). It was shown that the belemnite records previously known here and dated to the Late Jurassic or Early Cretaceous may be of Bajocian–Bathonian (Middle Jurassic) age. The stage of kimberlite magmatism of 177 ± 1.5 Ma, recently established in the northeastern part of the Siberian craton according to U–Pb geochronological data, falls on the time of the existence of belemnites of the genus Arcobelus. The estimated Late Bajocian–Early Bathonian age of the representative of the genus Pachyteuthis, previously found in kimberlites of the Obnazhennaya pipe, is consistent with the 40Ar/39Ar age (167 Ma), as well as with the age based on some paleomagnetic data (168 ± 11 Ma) reported for the pipe. Taking into consideration the new data on belemnites, the internal part of the shelf should be extended to the territory of the Kuoika kimberlite field in the paleogeographic schemes of the northeastern part of the Siberian Platform during the Toarcian–Early Bathonian. [ABSTRACT FROM AUTHOR]