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The South China Block, a region renowned for its extensive granite distribution and rich metal deposits, serves as a natural laboratory for the study of granite-related mineralization. This research focuses on the Tongtianmiao granite pluton, which is located at the intersection of the Qin-Hang and Nanling metallogenic belts and has been confirmed as a significant lithium mineral resource. Despite its discovery and ongoing development, the lithium-rich Tongtianmiao pluton has been understudied, particularly concerning its petrogenesis, which has only recently come to the forefront of scientific inquiry. By integrating an array of petrogeochemical data with geochronological studies derived from zircon and monazite dating, this study provides insights into the magmatic processes related to lithium enrichment in the Tongtianmiao granites. The Tongtianmiao granites are classified as A-type granites characterized by high SiO2 contents (69.18–78.20 wt.%, average = 74.08 wt.%), K2O + Na2O contents (4.59–8.34 wt.%, average = 6.86 wt.%), A/CNK > 1.2, and low concentrations of Ca, Mg, and Fe. These granites are enriched in alkali metals such as Li, Rb, and Cs but are significantly depleted in Ba, Sr, and Eu. They show no significant fractionation of light or heavy rare-earth elements but present characteristic tetrad effects. A finding of this study is the identification of multiple ages from in situ zircon U–Pb dating, which implies a prolonged history of magmatic activity. However, given the high uranium content in zircons, which could render U–Pb ages unreliable, emphasis is placed on the monazite U–Pb ages. These ages cluster at approximately 172.1 ± 1.1 Ma and 167.9 ± 1.6 Ma, indicating a Middle Jurassic period of granite formation. This timing correlates with the retreat of the Pacific subduction plate and the associated NE-trending extensional fault activity, which likely provided favorable conditions for lithium enrichment. The study concluded that the Tongtianmiao granites were formed through partial melting of crustal materials and subsequent underplating by mantle-derived materials, and were contaminated by strata materials. This process resulted in the formation of highly differentiated granite through magmatic differentiation and external forces. These findings have significant implications for understanding the petrogenesis of lithium-rich granites and are expected to inform future exploration endeavors in the Tongtianmiao pluton. [ABSTRACT FROM AUTHOR]

The eastern part of the northern margin of the North China Craton is a key metal metallogenic province in China, hosting many important rare metal and rare earth element (REE) deposits and having great resource potential. This study investigated the Saima deposit, a niobium (Nb) and tantalum (Ta) deposit and the Baerzhe deposit hosting zirconium (Zr), Nb and REEs. Based on previous LA-ICP-MS zircon U–Pb dating results obtained by the authors' team, this study compared the whole-rock geochemistry and whole-rock Sr–Nd–Pb isotopes of an orebody with its surrounding rocks. The geochemical characteristics of both deposits are used to systematically review the evolution of the alkaline magma and the differences in the physical and chemical conditions for enrichment and mineralisation of late-stage rare elements and REEs such as Nb, Ta and Zr. Comparing the mineralisation of the Saima and Baerzhe deposits, the alkaline magmatic evolution plays a crucial role in the enrichment of rare-earth elements, which are generally formed in the late stage of alkaline magmatic evolution. The Saima deposit, which has a metallogenic age of 224.40 ± 6.10 Ma, formed in nepheline syenites with high alkali (Na2O + K2O) and low MgO and CaO contents, with high TFeO/MgO ratios. The A-type granites formed in an extensional tectonic setting after the closure of the Paleo-Asian Ocean. The Baerzhe deposit, which has a metallogenic age of 125.2–122.15 Ma, formed in A-type alkali granites (orebody and surrounding rocks) that have high alkali (Na2O + K2O) and low MgO and CaO contents with high TFeO/MgO ratios, strong uranium (U) depletion and typical V-shaped distribution of REE. The mineralisation is controlled by melt–fluid interactions in the later stage of highly evolved magmas. The enrichment and mineralisation of rare elements and REEs in the eastern part of the north margin of the North China Craton are mainly associated with the high degree of evolution of alkaline magmas. [ABSTRACT FROM AUTHOR]

The paleoenvironment of shales can be reconstructed to some extent using the combinations or concentrations of elements that correlate strongly with environmental conditions. In this study, we analyzed rare earth elements (REEs), major elements, and trace elements in the marine-continental transitional shales (transitional shales for short) of the Shan 2³ submember of the Shanxi Formation in the southeastern Ordos Basin. The purpose is to deduce the paleoenvironmental conditions of the shales, encompassing paleoredox, paleoclimate, paleoproductivity, and paleo-provenance. The Shan 2³ submember comprises four sections, namely Shan 2³-1, Shan 2³-2, Shan 2³-3, and Shan 2³-4. The Ba/Al, P/Al, and Cu/Al ratios, along with biogenic barium (Babio), indicate that the paleoproductivity of the submember peaked during the Shan 2³-1 deposition and exhibited a downtrend upward in other sections. Trends in the Uau and the Ni/Co, V/Cr, U/Th, and V/Sc ratios suggest that suboxic conditions prevailed during the Shan 2³-1 deposition, with the oxidation level gradually increasing from Shan 2³-1 to Shan 2³- 4. C-value and the Sr/Cu vs. Ga/Rb cross-plot indicate a warm and arid paleoclimate during the Shan 2³-1 deposition, which transitioned to cooler, drier conditions during the deposition of other sections. Indicators sensitive to paleoclimate, such as the K/Rb and Th/U ratios, along with the ICV, PIA, and Chemical Index of Alteration (CIA), highlight elevated weathering from Shan 2³-2 to Shan 2³-4, with Shan 2³-1 exhibiting the weakest weathering during its deposition. As suggested by the REE data, the Zr/Sc vs. Th/Sr cross-plot, provenance discriminant functions, and the cross-plots of Hf vs. La/Th, Th vs. HfeCo, and PREE vs. La/Yb, the sedimentary provenance for the transitional shales of the Shan 2³ submember is of multiple origins, with significant contributions from the Upper Continental Crust (UCC). Discriminant diagrams, including those of TheCoeZr/10, TheSceZr/10, LaeTheSc, and K2O/Na2O vs. SiO2, suggest that the transitional shales of the Shan 2³ submember were primarily deposited under tectonic settings such as continental island arcs (CIAs) and passive continental margins (PCMs). [ABSTRACT FROM AUTHOR]

Understanding the origins of potential source rocks and unraveling the intricate connections between reservoir oils and their source formations in the Siwa Basin (Western Desert, Egypt) necessitate a thorough oil-source correlation investigation. This objective is achieved through a meticulous analysis of well-log responses, Rock-Eval pyrolysis, and biomarker data. The analysis of Total Organic Carbon across 31 samples representing Paleozoic formations in the Siwa A-1X well reveals a spectrum of organic richness ranging from 0.17 wt% to 2.04 wt%, thereby highlighting diverse levels of organic content and the presence of both Type II and Type III kerogen. Examination of the fingerprint characteristics of eight samples from the well suggests that the Dhiffah Formation comprises a blend of terrestrial and marine organic matter. Notably, a significant contribution from more oxidized residual organic matter and gasprone Type III kerogen is observed. Contrarily, the Desouky and Zeitoun formations exhibit mixed organic matter indicative of a transitional environment, and thus featuring a pronounced marine influence within a more reducing setting, which is associated with Type II kerogen. Through analysis of five oil samples from different wellsdSIWA L-1X, SIWA R-3X, SIWA D-1X, PTAH 5X, and PTAH 6X, it is evident that terrestrial organic matter, augmented by considerable marine input, was deposited in an oxidizing environment, and contains Type III kerogen. Geochemical scrutiny confirms the coexistence of mixed terrestrial organic matter within varying redox environments. Noteworthy is the uniformity of identified kerogen Types II and III across all samples, known to have potential for hydrocarbon generation. The discovery presented in this paper unveils captivating prospects concerning the genesis of oil in the Jurassic Safa reservoir, suggesting potential links to Paleozoic sources or even originating from the Safa Member itself. These revelations mark a substantial advancement in understanding source rock dynamics and their intricate relationship with reservoir oils within the Siwa Basin. By illuminating the processes of hydrocarbon genesis in the region, this study significantly enriches our knowledge base. [ABSTRACT FROM AUTHOR]

The presence of the olive tree in Tuscany, Italy, in its forms that have survived to the present day as an essential component of the landscape dates back many centuries. Global change is now threatening it. Therefore, it is important to find markers to enhance the olive tree environment in terms of its resilience. The aim of the research was to investigate the composition of soil bacteriomes in contrasting geochemical environments using a geochemistry approach based on the behavior of the REEs, inherited from parent rock material. Bacteriome assemblages and REE content were analyzed in 48 topsoils developed in six geochemical Tuscan environments. Combined geochemical, geoinformatic, and bioinformatic techniques highlighted the existence of four bacteriome assemblages depending on Light-REEs. Further results showed that the soil bioavailable fraction of REEs was related to parent rock materials, pH, and bacteriome composition. The most abundant bacteria were Microlunatus in graded fluvio-lacustrine soils, Gaiella in graded arenaceous soils, Bradyrizhobium in pyroclastic soils, and Rubrobacter in soils on gentle slopes of calcareous and carbonatic lithologies. This research represents a starting point to define new indicators able to assess the resilience of the olive trees in the Mediterranean landscape and characterize the territory of extra virgin olive oils. [ABSTRACT FROM AUTHOR]

The Game of Life (GoL) cellular automaton is modified to inject order during execution of the state transition algorithm by making selected stable structures permanently active while interacting with normal active sites to create novel structures. A survey of the modified automaton's phenomenology and an analysis of its dynamics are presented in the context of the physics of the self-organization of matter by viewing the GoL as an artificial chemistry. These new structures become seeds for additional phases of structure building, analogous to nature's gravitational and thermodynamic churning of the geosphere that created material structures in phases, beginning the transition from geochemistry to prebiotic chemistry and laying foundational substrates for life-enabling organizational processes in an emerging biosphere. Evidence of selective self-assembly during phase transitions is reported where several GoL still life structures, configured as permanently active seeds evolving with random collections of active sites, resulted in geometrically identical structures as the GoL reached an equilibrium state of static density. [ABSTRACT FROM AUTHOR]

The present paper addresses petrography, geochemistry and Ar‐Ar geochronology of a significant number of mafic dykes from the Paleo‐ to Neoarchean Bundelkhand Craton in central India. The majority of the dykes are NW‐SE oriented (with a few NE‐SW and ENE‐WSW) with tholeiitic, sub‐alkaline and basalt to basaltic andesite composition. The trace element geochemistry of these dykes indicates an island arc setting during emplacement. The Ar‐Ar mineral dating (plagioclase) of three representative dykes reveals an emplacement age between 1.53 and 1.46 Ga. This finding and earlier reports (2.1–1.73 Ga) point to sustained mafic magmatism throughout the Bundelkhand Craton in a preferred structural orientation between 2.1 and 1.46 Ga. Mafic magmatism was episodic and can be linked to the perpetual subduction accretion processes between the central Indian Archean continents during the development of the Columbia supercontinent. The mafic dykes were emplaced at 45° to the maximum compression direction (E‐W), that is, along the line of no finite longitudinal strain. This time equivalent widespread NW‐SE and NE‐SW trending mafic dyke system is also relatable along the adjacent continents (Singhbhum, Bastar) and thus opened up a new paradigm for the dyke's emplacement across the Indian cratons. [ABSTRACT FROM AUTHOR]

The felsic volcanogenic tuff known as 'green bean rock' (GBR) and its carbonates are widely dispersed across the western Yangtze Block. This study investigates the origin, tectonic setting and genesis of GBR, as well as the environmental disruptions evident in carbonates from the western edge of the Yangtze Block. The analyses include mineralogy, whole‐rock geochemistry and the isotopic composition of zircon Hf, carbon and oxygen in GBR samples from the western edge of the Yangtze Block. The geochemical profile of GBR shows enriched LREE, Th and U content, depleted levels of Nb, Ta, Sr, Ba, K, Rb and Ti, and strong‐to‐moderate negative Eu anomalies (δEu = 0.15–0.18). Zircon Hf isotopes exhibit S‐type geochemical affinities with low negative εHf(t) values (−13.3 to −5.7) and TDM2 ages of 1684–2110 Ma. This suggests that the volcanic ashes originate from the magma of an intermediate to felsic composition. X‐ray directionality data show that the most prevalent clay minerals are illite and illite/smectite. Lithium fixed in these minerals is likely to have leached from brine. Early Triassic variances in δ13C profiles are reliable indicators of environmental disturbances, pointing to cycles of devastation and restoration in marine ecosystems, interspersed with extraneous events including volcanic activity. The study posits that volcano eruptions may have prolonged biotic recovery after the end‐Permian mass extinction. [ABSTRACT FROM AUTHOR]

Voluminous Neoproterozoic intermediate to felsic rocks intruded the Neoarchean Douling Complex in the South Qinling Belt of Central China, which may provide new constraints on the controversial issue about the nature of the continental margin of the Yangtze Block during the Neoproterozoic. This study presents zircon U–Pb geochronology, whole‐rock geochemistry and Sr–Nd isotope of the Douling dioritic–granodioritic–granitic intrusion, aiming to clarify its petrogenesis and tectonic significance. The dioritic–granodioritic–granitic rocks yield similar zircon U–Pb ages ranging from 735 to 705 Ma. The enrichment of light rare earth elements (LREEs) and large‐ion lithophile elements (LILEs), and depletion of high‐ field‐strength elements (HFSEs) (e.g., Nb, Ta) are typical features of arc magmatic rocks. The whole‐rock Sr–Nd isotopic compositions show initial 87Sr/86Sr ratios ranging from 0.7034 to 0.7059, and εNd(t) values from −7.3 to −1.4. Elemental and isotopic data suggest that the Neoproterozoic dioritic–granodioritic–granitic rocks were co‐genetic and were generated by partial melting of lower crust materials combined with mantle‐derived melts. The granites were the derivative product of dioritic rocks by fractional crystallization of amphibolite, plagioclase, mica and zircon. Combined with literature data, we infer a subduction‐related setting for the northern margin of the Yangtze Block during the Middle Neoproterozoic, and a tectonic model of accretion along an Andean‐type active continental margin after the collision of the Douling micro‐block with the northern Yangtze Block is further proposed. [ABSTRACT FROM AUTHOR]

Organic matter and metal elements are commonly co-enriched in marine black shales. However, the element types vary among different shales and the relevant mechanisms of organo-metal co-enrichment are still unclear. The super-enrichment of organic matter and nickel in the ore bed of Early Cambrian marine black shale of southern China provides an ideal opportunity to investigate this mechanism. Herein, to clarify the coenrichment mechanism of organic matter and, the laminated structure of this ore bed was characterized and the geochemical and mineralogical proxies of different laminae were analyzed. The results indicated that there are four types of laminae in this ore bed, namely, siliceous laminae, calcareous laminae, clay minerals laminae, and organic-rich laminae. Clay minerals laminae and organic-rich laminae were deposited under anoxic environments, while siliceous laminae were deposited under strong oxidizing to anoxic environments. Neither organic matter nor are distributed homogeneously in the ore bed; organic matter is mainly concentrated in organic-rich laminae, while is largely enriched in clay minerals laminae. Clay minerals and organic matter have strong adsorption capacity for, and the adsorption capacity of clay minerals (such as illite) for is stronger than that of organic matter. Hydrothermal events and terrestrial input are key factors affecting the paleoenvironment and laminated structure during the deposition of the ore bed. Although organic matter and are co-enriched in the ore bed, their enrichment stages and conditions vary according to the geochemical differences among laminae. [ABSTRACT FROM AUTHOR]

Salinity is a crucial property of water body and is essential for the restoration of paleoecology and paleoenvironment. However, the theoretical method of application of elemental geochemical proxies to paleosalinity reconstruction is still underdeveloped. Moreover, accurate determination and reconstruction of paleosalinity and its variation in an offshore lacustrine basin have been extremely challenging thus far. This study presents detailed elemental geochemical investigations from the Zhanhua Sag in the southern Bohai Bay Basin to reconstruct the salinity variation in the Paleogene Eocene Shahejie Formation (50.8–33.9 Ma). Based on the variation of strontium barium ratio (Sr/Ba) and boron gallium ratio (B/Ga), we determined three typical salinity types of water body: salty water (Sr/Ba>0.5, B/Ga>6), brackish water (0.2

The subtropical to subpolar planktic foraminifera Globigerina bulloides is a calcifying marine protist, and one of the dominant foraminiferal species of the Nordic Seas. Previously, the relative abundance and shell geochemistry of fossil G. bulloides have been studied for palaeoceanographic reconstructions. There is however a lack of biological observations on the species and a poor understanding of its ecological tolerances, especially for high latitude genotypes. Here, we present observations from the first extensive culturing of G. bulloides under subpolar conditions, including the first low temperature (6–13°C) and variable salinity (30–38) experiments. Carbonate chemistry (pH and [CO32−]) was also manipulated. Experimental conditions were chosen to reflect a range of plausible past and future scenarios for the Nordic Seas. We found G. bulloides to be tolerant of environmental conditions well outside their optimal range (<10°C, salinity <33, pH <8). Observed life span was up to three months, which was attributed to a microalgal diet. Two alternative life strategies were employed, whereby individuals either experienced rapid growth and death, or a prolonged lifespan with minimal growth and death via slow decay. We posit this could help explain differences in geochemical signals recorded from different size fractions of fossil specimens used for palaeoceanographic reconstructions. [ABSTRACT FROM AUTHOR]

This study examines the potential for aquifer storage and recovery (ASR) in the brackish portion of the Edwards aquifer in New Braunfels, Texas. Successful ASR relies on understanding hydraulic properties, aquifer heterogeneity, water geochemistry, and geochemical processes during operations. The research aims to investigate the chemistries of native groundwater and injectant during ASR operation, estimate the hydraulic properties of the aquifer layers, and assess the recovery rate for the recovered groundwater meeting the total dissolved solids (TDS) threshold. The study found that native groundwater is of Na‐Cl facies due to halite dissolution and a possible basinal brine migration associated with the zone of greatest fault displacement. High sulfate ions in background native groundwater result from sulfate‐bearing minerals' dissolution in the Kainer and Person Formations. The injectant water is of Ca‐Mg‐HCO3 facies due to the carbonate‐rich composition of the aquifer host matrix and interaction with the Guadalupe River riverbed. During ASR operations, mixing controlled the shift in hydrochemical facies from Na‐Cl to Ca‐Mg‐HCO3.The study also suggests a possible connection between Kainer and Person Formations and preferential pathways in the targeted storage zone aquifer. The estimated conductivity values also indicate dominant horizontal flow via possible fracture pathways in both the Person and Kainer Formation storage zones. Recovery of groundwater meeting the TDS of 1000 mg/L requires a recovery rate of 0.03 m3/s for 60 days after 40‐day storage. This research emphasizes that understanding the hydrogeological conditions and geochemical processes is critical to ASR feasibility in brackish carbonate multi‐aquifer fractured systems. [ABSTRACT FROM AUTHOR]

The timing of extensional events in northern Gondwana remains elusive. In relations to this event, a new zircon U-Pb age and Hf isotopic compositions, and whole-rock geochemistry provided here for the amphibolites in the basement unit of the Menderes Massif (MM) within the Anatolide-Tauride Block (ATB). LA-ICP-MS U-Pb zircon dating of one sample yielded a crystallization age of 367.0 ± 2.5 Ma, providing the first record of Late Devonian (Famennian) mafic magmatism in the Menderes Massif. This sample contains inherited zircon grains with ages spanning from 588 Ma to 541 Ma, likely sourced from late Neoproterozoic country rocks. Chondrite-normalized rare earth element patterns exhibit enrichment in light rare earth elements and flat patterns for heavy rare earth elements, suggesting affinities with tholeiitic EMORB and ocean island basalt. The geochemical data, coupled with the positive εHf(t) values ranging from 0.5 to 7.8, indicate that the amphibolite likely originated from juvenile melts generated by partial melting of the asthenospheric mantle. This melt was subsequently modified by crustal contamination and fractional crystallization. Contemporaneous EMORB- and OIB-like mafic rocks are identified in the eastern Taurides and Iran, respectively. Both regional geological and geochemical evidence proposes that Late Devonian magmatism in the Anatolide-Tauride Block occurred in a within-plate tectonic setting. This magmatic activity might have been triggered by the northward subduction of the Paleotethys beneath the Pontides during the Devonian, a process that would produce a slab-pull force, creating an extensional tectonic regime along the northern margin of Gondwana. [ABSTRACT FROM AUTHOR]

The post-collisional evolution of the Tibetan lithosphere is of paramount significance to our understanding of collisional orogeny. It is generally postulated that the Lhasa lithospheric mantle was horizontally shortened and thickened coherently with the overlying crust to form a physical barrier, preventing Indian subduction beneath Tibet until the thickened mantle root was foundered during the Miocene. This study first identifies post-collisional oceanic-island basalt (OIB)-type magmatism in the Lhasa Block (LB), as attested by zircon U-Pb age (ca. 58 Ma) and geochemistry--positive Nb-Ta anomalies, high La/Yb, and depleted bulkrock Sr-Nd and zircon Hf isotopes, of diabase in the northern (inboard relative to Indus Suture) part of this block. Coupled with extensive early Paleogene arc-type magmatism in the southern-central LB and thermodynamic modeling, we suggest that these diabases were formed by partially molten upwelling asthenosphere near the base of continental crust, where much of the underlying lithospheric mantle had been removed due to Neo-Tethyan slab rollback and lithospheric delamination. Compared to OIB-type magmatism worldwide, the diabases investigated here were emplaced peculiarly in a region where the continental crust was under horizontal compression and shortening by coeval thrusting. Our study thus implies a decoupled deformation between the crust and mantle of the LB during the early Indian-Asian collision. [ABSTRACT FROM AUTHOR]

The northern margin of the North China Craton experienced prolonged tectono-magmatic evolution during the late Paleozoic-early Mesozoic in response to the southward subduction and closure of the Paleo-Asian Ocean. However, details about the subduction process and the timing of the tectonic transition from subduction to post-collision are still poorly constrained. Here, we identify two-stage crust-mantle interactions in the Wulashan area and report new geochronology, geochemistry, and Sr-Nd-Pb-Hf isotopic data for magmatic rocks that record such processes following the subduction and closure of the Paleo-Asian Ocean. The early Carboniferous Xiguanjing pluton features a bimodal suite of gabbro (ca. 333 Ma) and syenogranite (ca. 331 Ma). The gabbros have arc-like geochemical affinities, with low Nb/La (0.31-0.40) and La/Ba (0.04-0.09) ratios, and variable Rb/Y (1.22-2.94) ratios, as well as enriched, mantle-like Sr-Nd-Pb (87Sr/86Sri = 0.7046-0.7047; eNd(t) = -3.8 to -3.5; 206Pb/204Pbi = 17.078-17.141) and enriched to depleted Hf (eHf(t) = -4.5 to +6.2) isotopic values. Such geochemical signatures indicate that they were derived from partial melting of the subcontinental lithospheric mantle that was metasomatized by slabderived fluids, with minor involvement of asthenospheric components. In contrast, the contemporaneous syenogranites are characterized by lower negative eNd(t) (-13.5 to -12.1) and eHf(t) values (-16.3 to -8.2), which suggests that they were formed by partial melting of the lower crust. Late Triassic Shadegai and Xishadegai plutons are mainly composed of enclave-bearing syenogranite, and both mafic microgranular enclaves and syenogranites crystallized at ca. 233-231 Ma. The mafic microgranular enclaves have geochemical features similar to those of the early Carboniferous gabbros, and also have moderately enriched isotopic compositions (eNd(t) = -9.7 to -8.4; eHf(t) = -9.2 to -0.3), which suggests that they originated from interaction between mantle-derived magma and overlying crust-derived magma, with minor additions of asthenospheric melts in their sources. Field and petrological observations, coupled with the similar ages of the host granites and mafic microgranular enclaves, suggest a magmatic mingling process. Isotopic mixing models suggest that minor amounts (~10%-20%) of lower crustal materials were mixed during the formation of the mafic microgranular enclaves. The host syenogranites display calc-alkaline to alkalic and metaluminous to weakly peraluminous compositions, and negative eNd(t) (-15.0 to -12.1) and eHf(t) values (-16.4 to -9.8), which indicates that they were mainly derived from partial melting of the lower crust and experienced the injection of deep mantle-derived magmas. Our new data, along with previously published data for magmatic rocks in the northern margin of the North China Craton, suggest that the early Carboniferous bimodal intrusive rocks formed in a localized back-arc extensional regime that was probably triggered by slab rollback of the Paleo-Asian Ocean. However, the Late Triassic plutons formed in a postcollisional extensional regime in response to slab breakoff or lithospheric delamination. Temporal variations of Nd-Hf isotopes for the magmatism in the northern margin of the North China Craton suggest that tectonic switching from advancing to retreating subduction to post-collisional extension occurred during the late Paleozoic to early Mesozoic. We propose that a tectonic transition from subduction to post-collisional extension may have occurred during the Early-Middle Triassic, marking the final closure of the Paleo-Asian Ocean, which most likely took place at ca. 250-235 Ma. [ABSTRACT FROM AUTHOR]

The article discusses the role of polymorphic transformations of titanium oxides in contributing to economic uranium mineralization in sandstone. The authors conducted a study on sandstone samples from the Yaojia Formations in China and found that titanium oxides, specifically anatase and rutile, play a significant role in concentrating uranium. The study utilized various analytical techniques such as scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and electron microprobe analysis to characterize the titanium oxides and determine their trace element concentrations. The findings provide valuable insights into the mineralization processes of uranium in sandstone formations. [Extracted from the article]

Reservoir modeling consists of two key components: the reproduction of the historical performance and the prediction of the future reservoir performance. Industry-standard reservoir simulators must run fast on enormous and possibly unstructured grids while yet guaranteeing a reasonable representation of physical and chemical processes. However, computational demands limit simulators in capturing involved physical and geochemical mechanisms, especially when chemical reactions interfere with reservoir flow. This paper presents a mathematical workflow, implemented in IORSim, that makes it possible to add geochemical calculations to porous media flow simulators without access to the source code of the original host simulator. An industry-standard reservoir simulator calculates velocity fields of the fluid phases (e.g., water, oil, and gas), while IORSim calculates the transport and reaction of geochemical components. Depending on the simulation mode, the geochemical solver estimates updated relative and/or capillary pressure curves to modify the global fluid flow. As one of the key innovations of the coupling mechanism, IORSim uses a sorting algorithm to permute the grid cells along flow directions. Instead of solving an over-dimensionalized global matrix calling a Newton–Raphson solver, the geochemical software tool treats the species balance as a set of local nonlinear problems. Moreover, IORSim applies basis swapping and splay tree techniques to accelerate geochemical computations in complex full-field reservoir models. The presented work introduces the mathematical IORSim concept, verifies the chemical species advection, and demonstrates the IORSim computation efficiency. After validating the geochemical solver against reference software, IORSim is used to investigate the impact of seawater injection on the NCS Ekofisk reservoir chemistry. Article Highlights: The IORSim sorting algorithm decouples the nonlinear geochemical reaction calculations into recurring one-dimensional problems to assure numerical stability and computation efficiency. To the best of our knowledge, this work presents the mathematical concept, implementation, and application of topological sorting for the first time on (industry) field-scale problems. IORSim combines topological sorting with basis swapping and splay trees to significantly reduce computation times. Moreover, a high-speed forward simulation mode was developed to allow the post-advection of chemical components to visualize species distribution, water chemistry, and mineral interactions. If the geochemical reactions interfere with the fluid flow, the IORSim backward mode uses relative permeability curves to update the global fluid flow at each time step. We validate the implemented topological scheme on a reservoir grid, show the computation efficiency, and compare the impact of explicit, implicit, and grid refinement on numerical dispersion. The decoupled flow simulator and geochemical reaction calculations allow seamless integration of full-field reservoir models that contain complex geological structures, a large number of wells, and long production histories. The computation capabilities of IORSim are demonstrated by simulating and reproducing the impact of seawater injection in the southern segment of the giant Ekofisk field (more than 50 years of injection and production history). IORSim shows that seawater injection changed the Ekofisk mineralogy and impacted the produced water chemistry. In the investigated Ekofisk case, seawater promoted calcite dissolution and led to the precipitation of magnesite and anhydrite. Moreover, surface complexation modeling revealed that sulfate is adsorbed on the calcite surface. [ABSTRACT FROM AUTHOR]

In the summer of 2021, Greece experienced significant forest fires and mega-fires across multiple regions, leading to human casualties and damage to the natural environment, infrastructure, livestock, and agriculture. The current study aims to assess the ecosystem condition in terms of the natural regeneration and soil conditions of an area burnt by a forest fire (2021), specifically in the Ancient Olympia region situated in West Peloponnese (Ilia Prefecture), Greece. A standardized field sampling methodology was applied to record natural regeneration at chosen sites where a forest fire had also previously occurred (in 2007), resulting in the natural re-growth of the Pinus halepensis forest. Furthermore, an analysis was conducted on the geochemical, mineralogical, and sedimentological properties of soils obtained from this location. The findings of the research demonstrate the decline in the established natural regeneration of the Pinus halepensis forest and the overall tree layer. Species characteristic of post-fire ecological succession were observed in the shrub and herb layers, displaying varying coverage. The examination of soil mineralogy, sedimentology, and geochemistry indicated that the soil characteristics in the area are conducive to either natural or artificial regeneration. Ultimately, recommendations for landscape rehabilitation strategies are provided to inform decision-making processes, considering future climate conditions. [ABSTRACT FROM AUTHOR]

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Copyright of Geology & Exploration is the property of Geology & Exploration Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Coastal aquifers play an important role in marine ecosystems by providing high fluxes of nutrients and solutes via submarine groundwater discharge pathways. The physical and chemical characterization of these dynamic systems is foundational to understanding the extent and magnitude of hydrogeologic processes and their subsequent contributions to the marine environment. We describe a km‐scale experimental field site located in a glaciofluvial delta entering Kachemak Bay, Alaska. Our characterization applies geophysical (ERT and HVSR), hydrogeologic (grain size analyses, slug tests and tidal response analyses) and geochemical (major ions and stable water isotopes) methods to describe the complexity of coastal aquifers in proglacial environments currently experiencing rapid transformations. The hydrogeologic and geophysical techniques revealed thick (20–84 m) sediments dominated by sands and gravels and delineated zones of freshwater, brackish water and saltwater at both high and low tides within the subterranean estuary. Estimates of hydraulic conductivities via multiple approaches ranged from 2 to 250 m d−1, with means across the four methods within the same order of magnitude. Tidal response analyses highlighted a coastal aquifer in strong connection with the sea as evidenced by clear spring‐ and neap‐tidal signals within a proximal piezometric hydrograph. Geochemical sampling revealed coastal groundwaters as substantially enriched in solutes compared to proximal river samples with limited variability across seasons. A clear connection between the Wosnesenski River and the adjacent aquifer was also observed, with concentrated recharge from the river corridor during the meltwater season. This combination of approaches provides the basis for a conceptual model for coastal aquifer systems within the Gulf of Alaska and an upscaled mean daily yield of freshwater and solutes from the delta subsurface. Our findings are critical for subsequent numerical simulations of groundwater flow, tidal pumping and chemical reactions and transport in these understudied environments. This approach may be applied for low‐cost, large‐scale hydrogeologic investigations in coastal areas and may be particularly useful for remote sites where access and mobility are challenging. [ABSTRACT FROM AUTHOR]

Research of the depositional environment using geological mapping, petrography, gamma-ray (GR) log, palynology, and foraminifera fossils of the Bojongmanik Formation has led to the formation of several different conclusions about the transition to the marine environment, which are attractive to revisit. The expected results of this research are to determine the paleoenvironment of the Bojongmanik and Serpong Formations based on elemental geochemistry, the development of paleoenvironment proxies based on portable X-ray fluorescence (pXRF) in fluvial to transitional environments studies, and the contribution of paleoenvironment analysis to GR-log facies interpretation. The research methodology starts with GR-log facies analysis, Pearson's correlation, paleoenvironment analysis based on elemental affinity and elemental ratio, and comparing the paleoenvironment with GR-log-based facies. The paleoenvironment analysis based on elemental geochemistry resulted in the Bojongmanik Formation in the research area deposited at the tidal point bar, lagoon, and shoreface, while the Serpong Formation was deposited at the fluvial point bar and floodplain. Compared to previous research, the Bojongmanik Formation in the research area could be stratigraphically related to the upper Bojongmanik Formation. Proxies based on elemental geochemical affinities of carbonate-associated, carbonate-productivity, terrigenous-associated elements, and redox-sensitive trace elements show contrast changes between facies. Proxies based on the specific ratio show a detailed paleoenvironment for paleoclimate (Sr/Cu), paleosalinity (Sr/Ba), paleoredox (Cu/Zn), paleo-hydrodynamics and water depth (Zr/Rb and Fe/Mn), sediment provenance (Cr/Zr), and siliciclastic-dominated (Zr + Rb)/Sr. Adding a geochemistry element-based paleoenvironment analysis benefits from a more specific justification for GR-log facies interpretation. [ABSTRACT FROM AUTHOR]

Copyright of Uranium Geology is the property of Uranium Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Exploration in the mining sector results in the accumulation of extensive databases encompassing diverse geochemical datasets. The efficient processing of this multivariate data necessitates the application of advanced Python data analysis tools. Such an approach is essential for the extraction of criteria that will inform and optimize future exploration and mining operations. In this study, we utilize the Python language to explore the database of Aura Energy Company established within the uranium exploration project in the regions of Oued El Foula and Aïn Sder, where a total of 1065 drilling wells have been executed. The uranium deposit in Oued El Foula and Aïn Sder is of a surficial type and results from alteration and erosion of granites. Overall, economic concentrations of uranium are near the surface (with a depth of less than 10 m) and hosted in unconsolidated rock (mainly in colluviums) and igneous rocks (mainly granites). The uranium deposit exhibits an economic association with vanadium and thorium. The granites in the regions of Oued El Foula and Aïn Sder form from the melt at the upper continental crust. In addition, these granites show enrichment in LILE and depletion in HFSE which is a characteristic of alkaline granites resulting from wet melting and evolved melt. [ABSTRACT FROM AUTHOR]

Gold mineralisation in Goz-Beida within the southern Ouaddai massif in eastern Chad is hosted by quartz veins oriented NW-SE to NE-SW in Abilelaï and ENE-WSW to NE-SW in Kalaka. Quartz in the veins from both sites is brecciated with foliated wall-rock selvages and cut across Neoproterozoic metasedimentary rock. Alteration minerals include quartz, pyrite, chalcopyrite, galena, covellite, telluride, hematite, magnetite, sericite and chlorite, with the quartz and pyrite assemblage closely associated with gold mineralisation. The phases of hydrothermal alteration include silicification, sulphidation, ferruginisation, sericitisation and chloritisation. Parameters that consistently define alteration in the wall-rock include silicification, sulphidation, carbonitisation and K-feldspar alterations. Paragenetic and micro-structural characterisation of the vein minerals reveals that the gold-bearing veins might have been emplaced during brittle/ductile deformation events within a shear zones. The gold grains are alloyed with Ag. Gold grains that occur as inclusions in pyrite from Abilelaï show fineness values that vary between 438 and 860 and are characterised by inclusions of galena and telluride. The occurrence of galena as inclusions in gold and pyrite reflects a hydrothermal quartz vein sulphide system possibly related to a fluid system with inputs from the granitoids in the area. Free gold grains from Kalaka show fineness values that range from 903 to 922. The primary Ag content of the gold is typical of granitoid-related vein systems. Such high fineness values can be attributed to sulphidation as the dominant mechanism for ore deposition. Electron microprobe analysis on sulphide phases in the vein and wall-rock in Abilelaï depicts a Au-Ag-Pb assemblage. Analysis on sulphides and telluride phases in quartz veins from Kalaka reveals a characteristic Au-Ag-Pb-Te assemblage. Thus, brecciated stockwork sulphide and telluride-bearing veins and the wall-rock within an arc setting in prospective mining sites are the main target for gold in Goz- Beida. [ABSTRACT FROM AUTHOR]

The Eridania Basin system, located in the martian southern highlands, may have hosted long‐lived lacustrine hydrothermalism. Despite its multi‐basin scale and suggested longevity that should pervasively alter the landscape, evidence for consistent compositional signatures of lacustrine hydrothermalism across varying spatial scales is poorly known. Here we synthesize orbital data sets (derived from the Gamma Ray Spectrometer, GRS; Thermal Emission Spectrometer, TES; and Compact Reconnaissance Imaging Spectrometer for Mars, CRISM) to characterize the composition of Eridania's landscape from regional to outcrop scales. The bulk geochemistry representing decimeter depths is broadly on par with mafic igneous compositions seen elsewhere on Mars. The landscape‐scale mineralogy of Eridania suggests a compositional distinction between Eridania's northernmost basin and the remaining basins. Meanwhile, chloride mapping and analyses of amorphous silica and acid‐altered clay phases at the outcrop scale both show that mineralogical evidence for hydrothermal alteration and putative lacustrine activity is broadly limited to the northernmost basin, and that most other amorphous silica in Eridania is consistent with low‐to‐minimal water/rock weathering. This suggests either limited regional hydrothermalism or extensive mafic resurfacing occurred in Eridania, the latter of which is consistent with previous studies. Our findings collectively suggest that Eridania underwent local crystal hydrothermal alteration, perhaps confined to the northernmost basin, while much of the remainder of the Eridania's basins either experienced low‐temperature weathering or extensive resurfacing to at least meter scale depths by later volcanism. This supports prior inferences of spatially and temporally limited surface hydrology on Mars and extensive volcanic resurfacing of basins, as in the Gusev Crater. Plain Language Summary: Eridania Basin is a system of semi‐circular depressions in the Southern Highlands of Mars that is suggested to have once held a vast lake. This lake is inferred to have hosted hydrothermal activity for hundreds of millions of years. Such a long‐lived system should have led to mineralogical and geochemical signatures on large regional scales. Analysis of regional, local, and outcrop‐scale data—using orbital gamma ray, thermal, and near infrared spectra, respectively—indicates that the geochemistry of Eridania is consistent with relatively unaltered volcanic material, while mineralogical data suggest that aqueous activity and weathering may have been confined to a smaller region than previously thought. Materials indicating hydrothermal activities, such as chlorides and altered clays, are confined to the northernmost part of the basin system, while silica formed under low temperatures is found in the southern regions of Eridania. We propose that any hydrothermal activity in a lake setting was limited to the northernmost basin of Eridania, and that it may have been less long‐lived than previously anticipated. Evidence for ancient lakes may have also been obscured by volcanism. Key Points: Across regional to outcrop scales, Eridania Basin landscapes present compositions consistent with mafic resurfacingEridania's northern basin experienced a distinct, possibly longer‐lived aqueous alteration than the southern basinsA smaller watershed for Eridania, or a volcaniclastic cap, may help explain the limited evidence for lacustrine alteration in the Gusev Crater [ABSTRACT FROM AUTHOR]

Copyright of Acta Petrologica et Mineralogica / Yanshi Kuangwuxue Zazhi is the property of Acta Petrologica et Mineralogica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Petrologica et Mineralogica / Yanshi Kuangwuxue Zazhi is the property of Acta Petrologica et Mineralogica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We document an apparent downward displacement of the Matuyama‐Brunhes magnetic reversal by ∼20 m at Scotia Sea International Ocean Discovery Program Site U1538 (Pirie Basin) by comparison with the well‐defined paleomagnetic record at nearby Site U1537 (Dove Basin). Detailed stratigraphic correlation between the two sites is possible due to similar lithologic variations. However, the two sites have distinctly different porewater geochemistry. Notably, Site U1538 indicates a greater demand for electron acceptors to oxidize organic carbon and Fe2+ enrichment below the depth of SO42− depletion. Magnetic parameters indicate enrichment of an authigenic magnetic mineral with strong remanence properties around the depth of SO42− depletion (∼46 m at Site U1538) relative to magnetic parameters at correlative depths at Site U1537. Fe2+ enrichment below the depth of SO42− depletion is not predicted based on the energetically favorable order of electron acceptors for microbial respiration but is documented here and in other depositional settings. This indicates Fe2+ production exceeds the production of H2S by SO42− reduction, providing a geochemical environment that favors the production and preservation of ferrimagnetic remanence‐bearing iron sulfides over paramagnetic pyrite and, thus, a mechanism for deep chemical remanent magnetization acquisition at depths of tens of meters. The influence of authigenic ferrimagnetic iron sulfides on paleomagnetic signals can be difficult to demonstrate with magnetic properties alone; therefore, this finding has implications for evaluating the fidelity of magnetostratigraphic records with complementary geochemical data. Such situations should be considered in other depositional environments with similar porewater Fe2+ accumulation below the SO42− reduction depth. Plain Language Summary: Sediment on the seafloor is an archive of Earth history, including past climate variations, ice sheet dynamics, and geomagnetic field variations. The lattermost include a history of when the Earth's magnetic field flipped upside down in the past so that compass needles would have pointed to the South Pole instead of the North Pole. Scientists have a good understanding of when these flips happened and, once identified in sedimentary layers, the flips can be used to identify time horizons—which are useful for dating other events recorded by the sediment. In this study, we present two magnetic reconstructions from nearby locations that initially recorded the same geomagnetic signals. After deposition, one of the magnetic records changed as a result of chemical reactions that modified the magnetic minerals in the sediment, making it difficult to correlate to the geomagnetic time scale. We have a nearby record with minimal chemical modifications so we could identify the chemical reactions were likely responsible for the changes. This observation will provide additional insights into what signals to look for when studying similar complications from other locations in the world. Key Points: The last magnetic reversal at Scotia Sea Site U1538 is offset downward by ∼20 m compared to the more reliable Site U1537 recordFerrous iron enrichment below the sulfate reduction depth is observed at Site U1538Anomalous magnetic minerals and porewater differences reveal a geochemical setting conducive to chemical remanent magnetization acquisition [ABSTRACT FROM AUTHOR]

New whole‐rock major and trace element geochemistry from the Leka Ophiolite Complex in Norway is presented and compared to the geochemical evolution and proposed tectonomagmatic processes recorded in the Izu‐Bonin‐Mariana system. These data demonstrate that the Leka Ophiolite Complex formed as forearc lithosphere during subduction initiation. A new high‐precision zircon U‐Pb date on forearc basalt constrains the timing of subduction initiation in the "Leka sector" of the Iapetus Ocean to 491.36 ± 0.17 Ma. The tectonomagmatic record of the Leka Ophiolite Complex captures only the earliest stages of subduction initiation and is thereby distinct from some other Appalachian–Caledonian ophiolites of similar age. The diversity of Appalachian–Caledonian ophiolite records may represent differing preservation and exposure of a variable forearc lithosphere. Plain Language Summary: The Leka Ophiolite Complex (LOC) represents a preserved fragment of oceanic crust that formed during subduction in the Iapetus Ocean. Geochemical information recorded in the LOC rocks shows that it formed during the initial phase of subduction. The age of subduction initiation in the Iapetus Ocean is estimated at 491.36 million years ago based on isotopic dating of minerals within the LOC rocks. Other fragments of preserved oceanic crust with similar ages are found in the Appalachian–Caledonian mountains; however, their geochemical information suggests that they may have formed during different stages of the subduction zone development. We consider the variations in the oceanic crustal record to reflect selective preservation of different parts of the variable oceanic crust formed during the development of a subduction zone in the Iapetus Ocean. Key Points: The Leka Ophiolite Complex (LOC) preserves a record of geochemical variation from forearc basaltic to boninitic magmatism, reflecting formation during initiation and early evolution of a subduction zoneA 491.36 ± 0.17 Ma U–Pb zircon date for an LOC forearc basalt is considered to date subduction initiation in the "Leka sector" of the Iapetus OceanDifferences between the LOC pseudostratigraphy and the model Izu‐Bonin‐Mariana forearc may result from selective preservation of the spatially variable forearc lithosphere in addition to the specific history of formation, obduction, deformation, and uplift/erosion records [ABSTRACT FROM AUTHOR]

Source‐to‐sink systems respond to and therefore potentially record topographic and tectonic changes. North of the Tian Shan Belt, the Sikeshu subbasin of the SW Junggar Basin transitioned from active extension in the Triassic to post‐extensional subsidence in the Jurassic‐Cretaceous. Sediment in the Sikeshu subbasin has been shown to be derived from the Tianshan. However, the details of the source‐to‐sink system remain unclear and discrepancies exist between proxy records. The heavy minerals in the Middle Triassic in the Sikeshu subbasin are dominated by garnets. To investigate the garnet sources and decipher the Mesozoic source‐to‐sink evolution, we conducted petrological and sedimentary analysis and detrital garnet and tourmaline geochemistry. We found that the geochemistry of garnets in the Middle Triassic sandstone is most consistent with that of the skarns in the Yili Block (YB) in Tianshan, while the geochemistry of 55%–84% of garnets in other Mesozoic sandstones is consistent with that of garnets in amphibolites in the YB. The geochemistry of the tourmalines since the Upper Triassic is consistent with that of the meta‐sedimentary rocks in the YB and Central Tianshan Block. The dominance of garnets sourced from skarns in the Middle Triassic probably indicates a near‐source point provenance and the broader range of garnet compositions from the Upper Triassic–Lower Cretaceous suggests multiple sources. We infer that the point source changed to multiple sources, which is consistent with the zircon spectra changing from unimodal to multimodal. This change reflects the expansion of the drainage that accompanies a change from active rifting to a post‐rift stage. Key Points: Provenance changed from a point source from skarns during the syn‐rift stage to multiple sources during the post‐rift stageHigher relief in the Tianshan in the Triassic was reduced during the Jurassic‐CretaceousSediment recycling took place in the Early Cretaceous [ABSTRACT FROM AUTHOR]

We perform a set of reactive transport simulations in three‐dimensional fracture networks to characterize the impact of geochemical reactions on flow channelization. Flow channelization, a frequently observed phenomenon in porous and fractured subsurface rock formations, results from the spatially variable hydraulic resistance offered by a geological structure. In addition to geo‐structural features such as network connectivity, geometry, and hydraulic resistance, geochemical reactions, for example, dissolution and precipitation, can dynamically inhibit or enhance flow channelization. These geochemical processes can change the fracture permeability leading to increased flow channelization, which are localized connected regions of high volumetric flow rates that are seemingly ubiquitous in the subsurface. In our simulations, fractures partially filled with quartz are gradually dissolved until quasi‐steady state conditions are obtained. We compare the flow field's initial unreacted and final dissolved states in terms of flow and transport observations. We observe that the dissolved fracture networks provide less resistance to flow and exhibit increased flow channelization when compared to their unreacted counterparts. However, there is substantial variability in the magnitude of these changes which implies that the channelization strongly depends on the network structure. In turn, we identify the interplay between the particular network structure and the impact of geochemical dissolution on flow channelization. The presented results indicate that geological systems that have been weathering or reactive for longer times in older landscapes are likely to have increased flow channelization compared to their equivalent but younger counterparts, which implies a time dependence on flow channelization in fractured media. Plain Language Summary: Fractures are the primary pathways for fluid flow and solute transport in Earth's subsurface. In many of these systems, fluids passing through the fractures are out of equilibrium with the resident minerals, and various geochemical reactions occur. These geochemical processes can change the resistance to flow offered by the fractures, leading to increased flow channelization, which are localized connected regions of high flow rates. However, quantification of these impacts has been limited to the computational burden of performing requisite simulations. Through a series of reactive transport simulations in fractured media, we characterize the influence of dissolution on flow channelization using observations of flow and transport properties. We compare flow and transport in the initial unreacted state and in the final dissolved state to better understand how geochemical reactions influences the flow properties of the network medium. We observe that the unreacted fracture networks provide lower resistance to flow and exhibit increased flow channelization. The results suggest that older geological systems ought to have increased flow channelization when compared to their younger counterparts. Key Points: We characterize the impact of geochemical dissolution on flow channelization in fractured media using reactive transport simulationsWe observe that the dissolved fracture networks provide less resistance to flow and exhibit increased flow channelizationThere is a dissolution feedback loop between primary sub‐networks and geochemical reactions on flow channelization [ABSTRACT FROM AUTHOR]

The Pleiades Volcanic Field is made up of some 20 monogenetic, partly overlapping scoria and spatter cones, erupted in the last 900 ka, cropping out from the ice close to the head of the Mariner Glacier in northern Victoria Land, Antarctica. Erupted products vary from hawaiite to trachyte, defining a complete mild Na‐alkaline differentiation trend. Mafic samples are characterized by multi‐elemental patterns typical of OIB magmas, moderately low 87Sr/86Sr (0.7037) and high 143Nd/144Nd (0.51284), with a clear within‐plate affinity, indicating a subcontinental lithospheric source. With increasing SiO2, 87Sr/86Sr ratios increase up to 0.7052 and 143Nd/144Nd decrease to 0.51277, supporting the hypothesis of open‐system evolution, with significant crustal assimilation during fractional crystallization. The erupted volume of most evolved products (∼7 km3), according to fractionation models, suggests that primitive magmas should have been more than 10 times larger, indicating the occurrence of a large magma plumbing system, unexpected for a volcanic field of monogenetic scoria cones. The occurrence of a complete fractionation trend with large magma chambers and large assimilation rate is unusual, if not unique, among the alkali basaltic volcanic fields and it is matched by a climax of activity during the last glacial maximum (30 ka), as indicated by new 40Ar‐39Ar ages (30 ± 3 ka and 25 ± 2 ka) for samples from the two most prominent edifices. Therefore, we hypothesize a role of a thick ice cap in suppressing eruptions and ultimately leading to prolonged magma residence time in the subsurface, favoring significant fractionation coupled with unusual high rates of crustal assimilation. Plain Language Summary: The Pleiades volcanic field is made up of some 20 monogenetic scoria and spatter cones, which erupted in the last 900 ka close to the head of the Mariner Glacier in northern Victoria Land, Antarctica. The erupted products are very unusual for alkali basaltic volcanism: indeed, whereas few samples show clear within‐plate subcontinental lithospheric characteristics and were directly derived from the mantle source, most of the products formed after extensive fractional crystallization matched by significant crustal assimilation, implying that primitive magma volumes are 10 times larger than outcropping products in an unusually large magma plumbing system. These peculiar features coincided with a climax of activity during the last glacial maximum (30–25 ka). Therefore, we speculate that a thick ice cap favored high rates of crystal fractionation coupled with crustal assimilation and was responsible for increasing magma residence times in chambers at crustal depths and suppressing the eruptive potential of magmas. Key Points: The Pleiades complex (NVL, Antarctica) is made up of some 20 monogenetic cones aged 900–0 ka, defining a complete Na‐alkaline trendFractionation models show much larger volumes of primitive magmas, indicating the occurrence of an unusually large magma plumbing systemA climax of activity occurred during the last glacial maximum (30 ka). Thickness variation of the ice cap may have influenced volcanic activity [ABSTRACT FROM AUTHOR]

Copyright of Acta Geoscientica Sinica is the property of Acta Geoscientica Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ImportanceThe ability to detect extracellular environmental conditions is a fundamental property of all life forms. Because microbial two-component sensor systems convert information about extracellular conditions into biochemical information that controls their behaviors, we evaluated how two-component sensor systems evolved within the deep Earth across multiple sites where abiotic and biotic properties vary. We show that these sensor systems remain abundant in microbial consortia at all subterranean sampling sites and observe correlations between sensor system abundances and abiotic (dissolved organic carbon variation) and biotic (consortia diversity) properties. These results suggest that multiple environmental properties may drive sensor protein evolution and highlight the need for further studies of metagenomic and geochemical data in parallel to understand the drivers of microbial sensor evolution.

Abstract: The Cross-Hosgri slope is a bathymetric lineament that crosses the main strand of the Hosgri fault offshore Point Estero, central California. Recently collected chirp seismic reflection profiles and sediment cores provide the basis for a reassessment of Cross-Hosgri slope origin and the lateral slip rate of the Hosgri fault based on offset of the lower slope break of the Cross-Hosgri slope. The Cross-Hosgri slope is comprised of two distinct stratigraphic units. The lower unit (unit 1) overlies the post–Last Glacial Maximum transgressive erosion surface and is interpreted as a Younger Dryas (ca. 12.85–11.65 ka) shoreface deposit based on radiocarbon and optically stimulated luminescence (OSL) ages, Bayesian age modeling, seismic facies, sediment texture, sediment infauna, and heavy mineral component. The shoreface was abandoned and partly eroded during rapid sea-level rise from ca. 11.5 to 7 ka. Unit 2 consists of fine sand and silt deposited in a midshelf environment when the rate of sea-level rise slowed between ca. 7 ka and the present. Although unit 2 provides a thin, relatively uniform cover over the lower slope break of the older shoreface, this feature still represents a valuable piercing point, providing a Hosgri fault slip rate of 2.6 ± 0.8 mm/yr. Full-waveform processing of chirp data resulted in significantly higher resolution in coarser-grained strata, which are typically difficult to interpret with more traditional envelope processing. Our novel combination of offshore radiocarbon and OSL dating is the first application to offshore paleoseismic studies, and our results indicate the utility of this approach for future marine neotectonic investigations.

Sampling strategies used in paleomagnetic studies play a crucial role in dictating the accuracy of our estimates of properties of the ancient geomagnetic field. However, there has been little quantitative analysis of optimal paleomagnetic sampling strategies and the community has instead defaulted to traditional practices that vary between laboratories. In this paper, we quantitatively evaluate the accuracy of alternative paleomagnetic sampling strategies through numerical experiments and an associated analytical framework. Our findings demonstrate a strong correspondence between the accuracy of an estimated paleopole position and the number of sites or independent readings of the time-varying paleomagnetic field, whereas larger numbers of in-site samples have a dwindling effect. This remains true even when a large proportion of the sample directions are spurious. This approach can be readily achieved in sedimentary sequences by distributing samples stratigraphically, considering each sample as an individual site. However, where the number of potential independent sites is inherently limited the collection of additional in-site samples can improve the accuracy of the paleopole estimate (although with diminishing returns with increasing samples per site). Where an estimate of the magnitude of paleosecular variation is sought, multiple in-site samples should be taken, but the optimal number is dependent on the expected fraction of outliers. The use of filters based on angular distance helps the accuracy of paleopole estimation, but leads to inaccurate estimates of paleosecular variation. We provide both analytical formulas and a series of interactive Jupyter notebooks allowing optimal sampling strategies to be developed from user-informed expectations.

Abstract: Variations in fault zone maturity have intermittently been invoked to explain variations in some seismological observations for large earthquakes. However, the lack of a unified geological definition of fault maturity makes quantitative assessment of its importance difficult. We evaluate the degree of empirical correlation between geological and geometric measurements commonly invoked as indicative of fault zone maturity and remotely measured seismological source parameters of 34MW ≥ 6.0 shallow strike‐slip events. Metrics based on surface rupture segmentation, such as number of segments and surface rupture azimuth changes, correlate best with seismic source attributes while the correlations with cumulative fault slip are weaker. Average rupture velocity shows the strongest correlation with metrics of maturity, followed by relative aftershock productivity. Mature faults have relatively lower aftershock productivity and higher rupture velocity. A more complex relation is found with moment‐scaled radiated energy. There appears to be distinct behavior of very immature events which radiate modest seismic energy, while intermediate mature faults have events with higher moment‐scaled radiated energy and very mature faults with increasing cumulative slip tend to have events with reduced moment‐scaled radiated energy. These empirical comparisons establish that there are relationships between remote seismological observations and fault system maturity that can help to understand variations in seismic hazard among different fault environments and to assess the relative maturity of inaccessible or blind fault systems for which direct observations of maturity are very limited.

At a geologic CO2 sequestration (GCS) site, geologic uncertainty usually leads to large uncertainty in the predictions of properties that influence metrics for leakage risk assessment, such as CO2 saturations and pressures in potentially leaky wellbores, CO2/brine leakage rates, and leakage consequences such as changes in drinking water quality in groundwater aquifers. The large uncertainty in these risk-related system properties and risk metrics can lead to over-conservative risk management decisions to ensure safe operations of GCS sites. The objective of this work is to develop a novel approach based on dynamic risk assessment to effectively reduce the uncertainty in the predicted risk-related system properties and risk metrics. We demonstrate our framework for dynamic risk assessment on two case studies: a 3D synthetic example and a synthetic field example based on the Rock Springs Uplift (RSU) storage site in Wyoming, USA. Results show that the U.S. National Risk Assessment Partnership's Open Source Integrated Assessment Model (NRAP-Open-IAM) coupled with a conformance evaluation can be used to effectively quantify and reduce the uncertainty in the predictions of risk-related system properties and risk metrics in GCS.

Abstract: Venus' tectonic evolution is not well understood. Thousands of kilometers of possible subduction sites on Venus have been identified along networks of rift zone trenches called chasmata. Rift zones are strong candidates for tectonic recycling due to pre‐existing weaknesses in the lithosphere. Recently, peel‐back delamination (PBD) was proposed as a mechanism of regional‐scale lithospheric recycling initiated at Venusian rift zones (Adams et al., 2022, https://doi.org/10.1029/2022je007460). PBD occurs when the lithospheric mantle becomes sufficiently thick and negatively buoyant to decouple and peel away from the overlying crust remaining at the surface. Both positively and negatively buoyant lithosphere were shown to undergo buoyancy‐driven PBD, though delamination is inhibited by increasing positive plate buoyancy. In this study, we use 2D numerical models to verify that delamination can be initiated in thinner, more positively buoyant lithosphere than in models with no plume‐rift interactions. Our results show that plume‐induced PBD in positively buoyant plates is facilitated by the excess negative buoyancy in the lithospheric mantle and increasing plume buoyancy force, and it is inhibited by increasing crustal buoyancy and decreasing rift width. We propose an age‐progressive framework for delamination at rift zones, where young, thin plates require a larger plume buoyancy force to be destabilized than thicker, yet still positively buoyant plates. We use lithospheric thickness constraints to predict PBD may be most likely to initiate near the Dali‐Diana Chasmata system.

In high-level nuclear waste (HLW) repositories, concrete and compacted bentonite are designed to be employed as buffer materials, which may raise a problem of interactions between concrete and bentonite. These interactions would lead to mineralogy transformation and buffer performance decay of bentonite under the near field environment conditions in a repository. A small-scale experimental setup was established to simulate the concrete-bentonite-site water interaction system from a potential nuclear waste repository in China. Three types of mortars were prepared to correspond to the concrete at different degradation states. The results permit the determination of the following: (1) The macro-properties of Gaomiaozi (GMZ) bentonite (e.g. swelling pressure, permeability, the final dry density, and water content of reacted samples); (2) The composition evolution of fluids from the synthetic site water-concrete-bentonite interaction systems; (3) The sample characterization including Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). Under the infiltration of the synthesis Beishan site water (BSW), the swelling pressure of bentonite decreases slowly with time after reaching its second swelling peak. The flux decreases with time during the infiltrations, and it tends to be stable after more than 120 d. Due to the cation exchange reactions in the BSW-concrete-bentonite systems, the divalent cations (Ca and Mg) were consumed, and the monovalent cations (Na and K) were released. The dissolution of minerals in the bentonite such as albite causes Si increasing in the pore water. It was concluded that the hydro-mechanical property degradation of bentonite takes place when it comes into contact with concrete mortar, even under low-pH groundwater conditions. The soil dispersion, the uneven water content, and the uneven dry density in bentonite samples may partly contribute to the swelling decay of bentonite. Therefore, the direct contact with concrete has an obvious effect on the performance of bentonite.

Anambra and Gongola basins are part of the sedimentary inland basins in Nigeria characterized by fossil fuels and in response to its present energy problem, Nigeria has shifted its power generating focus to coal. The studied coals were obtained from two localities, namely Ankpa and Maiganga in Kogi and Gombe States, respectively. The coals were investigated to determine its quality in terms of use and resource potential. The coals were analyzed by proximate, ultimate, elemental, mineralogy and scanning electron microscopy-energy dispersive spectrometry analyses. The objectives of the study are to determine the coals cokability, rank, paleoenvironments, hydrocarbon potential, and slagging tendency. The average values of moisture content, ash, volatile matter, and fixed carbon are 5.54%, 16.42%, 48.45%, and 30.71%, respectively, for Ankpa coals, while Maiganga recorded 10.68%, 8.60%, 44.33%, and 36.41%, indicating high volatile sub-bituminous non-coking coals that are optimum for combustion and electric power generation. The Van Krevelen plot based on the H/C vs. O/C showed Type IV kerogen. The XRD results, correlation plots, and Detrital Authigenic Index (DAI) values of 7.49 and 13.49 in Ankpa and Maiganga coals, respectively, indicated that Ankpa coals are enriched in authigenic minerals like quartz, pyrite, and calcite, while kaolinite and quartz were probable detrital minerals in the Maiganga coals. The agglomeration of the coals deduced by Base/Acid (B/A), Silicon ratio (G), Silica/Alumina (S/A), Iron/Calcium (I/C), Carbon/Hydrogen (C/H), and Fixed Carbon/Volatile matter (FC/V) showed weak–medium-strong for the Ankpa coals and strong for Maiganga coals.

The Mélange in Lamphun Province, situated in the southern region of the Chiang Mai-Chiang Rai Suture Zone (CMCRSZ), remains inadequately explored. This study employs field investigations and petrographic analysis to delineate the characteristics of the CMCRSZ Mélange, identifying nine distinct rock units. These units include Carboniferous quartz arenite interbedded with fine-grained sedimentary rocks, Permian lithic graywacke, Permian limestone hosting Pseudodaliolina sp. and Schwagerinid sp., Triassic chert containing Anisian radiolarian fossils, and ocean island basalt. This area exhibits complex folding and thrusting, accompanied by granitic intrusions and low-grade metamorphic rocks within a finer-grained sedimentary matrix. Stratigraphic assessments trace the primary material of the accretionary complex to the upper strata of the oceanic plate stratigraphy. Geochemical analyses indicate the mafic rocks as alkaline to subalkaline basalts, indicative of formation through an alkaline magma series, a conclusion supported by rare-earth element patterns. Sr/Nd isotope classification suggests ocean island tectonics for these rocks. The formation of the CMCRSZ Mélange occurred during the Paleo-Tethys oceanic crust subduction beneath the Indochina Terrane at the Permian-Triassic Boundary, accumulating diverse materials in a dynamically evolving tectonic context. Furthermore, S-type Triassic granites emerged post-collision during the Indosinian Orogeny following the thrusting of the CMCRSZ onto Sibumasu.

The Arctic region is covered with numerous small lakes whose ecosystems are vulnerable to current climate warming and resultant changes in water temperature, ice-cover duration and lake levels. Data on thermal features of these lakes are sparse, which hinders our understanding of the possible ecosystem impacts of the warming climate and climate feedbacks at larger spatial scales. We investigated spatial–temporal variations of lake surface water temperatures (LSWT) in 12 Arctic lakes in north-west Finnish Lapland and explored the predominant drivers of LSWTs by continuous year-round observations. The lake surface temperature data were recorded using thermistors at bi-hourly resolution during the years 2000, 2007–08 and 2019–2021. A large regional heterogeneity was observed in the timing of the maximum and minimum LSWTs and the overall patterns of the annual cycle. Our results reveal that July air temperature, maximum lake depth and altitude explained most of the variance in the summer LSWT (> 85%). The remaining variance was related to geographic location (longitude and latitude), lake morphometric features, such as lake area and catchment area, and certain physico-chemical characteristics, such as Secchi depth and dissolved organic carbon content. Our results provide new insights into thermal responses of different types of small Arctic lakes to climate change.

The Sichuan Basin, located in southwestern China, is considered the primary producing area for shale gas development in the country. Its rich shale gas reserves have made it a significant contributor to China’s energy production. Within the Sichuan Basin, northeast Sichuan has emerged as a region of particular interest for shale gas development. In order to investigate the controlling factors and enrichment patterns of organic matter-rich shales from the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in northeast Sichuan, inductively coupled plasma mass spectrometry (ICP–MS) was used to analyze 14 shale samples from the Wufeng Formation-Longmaxi Formation in northeast Sichuan. Combined with the characteristics of logging curves, the sedimentary system, redox conditions, terrestrial debris input, primary productivity, and paleoclimate relationship of the Wufeng Formation to the Longmaxi Formation were explored. As a result, three third-order sequences (SSQ1, SSQ2, and SSQ3) were identified, and the sea level experienced a process from high-low-high-low, which, in combination with the shale elemental parameters of w(V)/w(Cr), w(V)/w(V+Ni), w(Ni)/w(Co), w(Sr)/w(Cu), w(Sr)/w(Ba), and T (℃), indicated that the Wufeng Formation-Longmaxi Formation underwent an oxidized-poorly oxygenated-anoxic reduced-poorly oxygenated-oxidized freshwater environment; the climate has undergone a warm-humid, dry-cold, warm-humid, dry-cold, warm-humid evolution, and the temperature has gone through the process of decreasing – increasing – decreasing – increasing. The organic matter enrichment pattern of the Wufeng Formation-Longmaxi Formation in northeast Sichuan can be divided into a Ⅲ stage pattern. Stage Ⅰ, the depositional period from the Wufeng Formation to the bottom of the Longmaxi Formation, is a stage of gradual increase in organic carbon; stage Ⅱ, the depositional period of the middle part of the Longmaxi Formation, is a stage of enrichment of organic carbon (sweet-spot member); and stage Ⅲ, the depositional period of the upper part of the Longmaxi Formation, is a stage of gradual decrease in organic carbon. It is expected to provide a basis for the exploration of shale gas in northeast Sichuan, and the next step will be to carry out research on the resource response of major geological events to organic matter enrichment in the study area and deepen the shale gas enrichment model.

Abstract Diverse applications and tremendous usefulness of siliciclastic sedimentary sands make investigation into their mechanics of behaviour very essential globally. This study examines the convergence or otherwise of the specimens in compression; physical, fabric, chemical and mineralogical characteristics and their relationships with compression behaviour; shape characteristics, possible particle breakage and their overall effect on the behaviour of siliciclastic sedimentary sands obtained from two locations. The findings are as follows; (a) Siliciclastic sedimentary sands are poorly graded and coarse in nature. (b) The fabrics are characterized by aggregation of sub rounded particles and smaller particles tend to combine with fines to form coatings around bigger particles. (c) Chemical compositions are predominantly silica and alumina and heamatite are significant. (d) Quartz dominates the mineralogy and the other minerals are muscovite, albite, orthoclase and chlorite. (e) The samples have convergent behaviour and the compressibility is not significantly different but lower than the related materials. (f) The original particle is sub round in shape and the particles become sub angular after the test with no relationship between particle shape and compression behaviour. (g) The particle breakage is linked to coarser nature of the specimens and the overall effect of particle breakage on the compression behaviour of siliciclastic sedimentary sand is small.

This study aims to contribute to understanding the processes influencing the spatial distributions of trace metal elements in surface sediments of Brenne's ponds (France) and assess potential pollution levels in the area. It was motivated by the lack of knowledge regarding the hydrogeochemical dynamics of limnic entities, which are ponds. To achieve this, 25 sediment samples were collected from Pond Thomas , considered as a ‘sentinel pond’, and underwent analysis for grain size, total organic carbon (TOC) concentrations, and trace metal elements (TMEs) (specifically Cu, Ni, Pb, As, Zn, Cr, and Cd). The results revealed that trace metal elements are primarily concentrated in two areas: the northwest section and the upstream region in the southern part of the pond. Applying various pollution indicators such as the enrichment factor (EF), geo-accumulation index (Igeo), and potential ecological risk index (RI), it was found that Pb and As are the most enriched elements, with respective EFs of 3.5 and 4.9. Their average concentrations exceed geochemical background values by 4 and 5.68 times in certain samples. The sediments in the southern part of the pond showed moderate contamination levels for As and Pb, with moderate to severe pollution (2 < Igeo < 3), reaching a maximum Igeo of 2.26 for As. Although the RI values across the pond are relatively low, Cd and As still pose moderate potential ecological risks. Additionally, principal component analysis and Pearson correlation analysis indicated two sources of TMEs in the area: Zn, As, Ni, Cd, Pb, and Cr are primarily from natural sources, while Cu appears to have a local anthropogenic origin.