The late Cambrian Steptoean positive carbon isotope excursion (SPICE) coincided with the end-Marjuman trilobite extinction and an episode of global ocean euxinia. However, the mechanism that sustained euxinia for similar to 2-3 m.y. remains unclear. To address this, a novel combination of carbonate-associated phosphorus (CAP) and iodine [I/(Ca + Mg)] ratios was analyzed at four sites representing a range of water depths across the central Missouri intrashelf basin. Our data demonstrate that CAP rose during the SPICE, in parallel with elevated delta 13C values and expanded euxinia, indicating increased phosphate availability in the surface ocean. In contrast, I/(Ca + Mg) ratios remained low, demonstrating persistent oxygen-poor conditions in shallow seas. These characteristics can be linked to enhanced phosphorus release and recycling in the ocean due to expanded seafloor euxinia. Based on a coupled oceanic carbon-phosphorus model, we infer that elevated phosphorus levels boosted primary productivity in the surface ocean, leading to increased oxygen generation and enhanced particulate export, sustaining oceanic euxinia until the feedback was broken by rising atmospheric O2 levels. Our study highlights phosphorus recycling as a key driver of late Cambrian ocean redox instability.

Marine carbon-sulfur cycles experienced long-term frequent perturbations through the Latest Permian to Early Triassic. However, relationships between carbon and sulfur isotopes are still unclear. Here, we report δ13Ccarb and δ34SCAS, and elemental proxies (UEF, MoEF, Mn/Th, Cd/Mo and Co × Mn) from the Wuchiapingian to Spathian successions (Zuodeng Section) in the southern Nanpanjiang Basin, South China. Sudden decreases in both UEF and MoEF values (from ∼150 to < 10, and ∼60 to < 10, respectively) and a gentle increase in Mn/Th ratios (< 200 to ∼1 000) indicate a locally anoxic seawater condition during the Late Permian and an oxic condition during the Early Triassic. Variations of Cd/Mo, Co × Mn and TOC suggest that the Late Permian anoxic condition was related to locally intensive oceanic circulation (e.g., upwelling) and higher marine productivity, which was probably controlled by a relatively cool climate regime, whereas the Early Triassic climate warming may have resulted in intensive oceanic stratification, suppressed marine productivity, and thus narrowed the spatial distribution of the oxygen minimum zone, leaving the study site apart from anoxic water mass in that time. Both δ13Ccarb and δ34SCAS excursions were coupled during the Griesbachian and Dienerian substages probably due to elevated or suppressed marine productivity and co-burial of organic matter and pyrite driven by climatic variations. Decoupled δ13Ccarb-δ34SCAS excursions occurred during the Late Permian and the Smithian global warming, respectively probably because of elevated bacterial sulfate reduction and pyrite burial rate induced by serious global-oceanic anoxia. This study deciphers that dynamic variations of marine carbon-sulfur cycles may have been controlled by extremely environmental changes through the Late Permian to Early Triassic.

Disseminated mineralization is responsible for much of the production from orogenic gold deposits, and deciphering the nature of reactive fluid flow across the macro-to microscopic scale is crucial for understanding the mineralization processes. We integrated structural analysis, microstructural observations, whole-rock geochemistry, and thermodynamic modeling at the Liba orogenic gold deposit in the West Qinling orogen, central China, aiming to unravel the behavior of fluid in slate-hosted disseminated mineralization. The presence of deformed slaty foliation and hydrothermal sericite S-C fabrics indicates that the east-west-striking orebodies are hosted within sinistral brittle-ductile shear zones, which act as deposit-scale fluid migration conduits. The spatial distribution of pyrite within the mineralized slates closely aligns with pore networks and grain boundaries, suggesting that grain-scale enhanced permeability and fluid flow during mineralization were primarily accommodated by microcracking along grain boundaries. Combined with whole-rock geochemical data and thermodynamic modeling, we reveal that under conditions where rock permeability is sufficient for fluid transport, gold mineralization efficiency depends on the degree of reaction between the reactive fluid and Fe-bearing minerals. Compared to siliceous slate, the higher abundance of Fe-bearing minerals in argillaceous slate enhances reactivity at the fluid-mineral interface, promoting sulfide formation and gold precipitation. This study demonstrates that the physicochemical interplay between structural deformation and geochemical reactivity fundamentally controls disseminated mineralization in slatehosted orogenic gold systems.

A comprehensive assessment of hydropower’s climate impact requires considering both greenhouse gas (GHG) emissions and carbon burial in sediment. This study examines the Wujiang River in southwestern China, where seven cascade reservoirs were categorized into upper (Group 1), middle (Group 2), and lower (Group 3) reaches according to their geographic locations and proximity to key sediment source areas. The G-res Tool was conducted to simulate greenhouse gas (GHG) emissions from these reservoirs, which ranged from 2,231 to 19,774 t CO2e yr−1 after impoundment. The primary influencing factors include reservoir age, surface area, and water retention time. Due to the steep mountainous terrain, deep valleys, and pre-impoundment clearing, the GHG emissions from these groups of reservoirs are lower than those of other reservoirs at similar latitudes worldwide. As the cascade reservoirs were gradually constructed, sediment accumulated behind the dams, leading to the long-term storage of terrigenous carbon. Notably, the upstream Group 1 reservoirs exhibited an exceptionally high terrigenous carbon storage rate during their early impoundment phase (7,468 gC m−2 yr−1), largely due to significant sediment input from the upstream Yachihe Basin, a major sediment source. In contrast, the downstream reservoir (Group 3) exhibited relatively smaller total terrigenous carbon storage rates (319 gC m−2 yr−1), corresponding to reduced sediment retention. Despite variations in sediment retention among the groups, the total terrigenous carbon storage of all groups of reservoirs (ranging from 43,020 to 999,403 tC yr−1) exceeded their post-impoundment GHG emissions. By integrating carbon emissions and sedimentary carbon sequestration across a cascade system, this study provides a system-scale carbon balance assessment of hydropower reservoirs. Our results indicate that the cascade reservoir systems, like those on the Wujiang River, function as a net terrigenous carbon storage, mainly due to the large sediment sequestration. These findings highlight the importance of incorporating both carbon emission and storage into carbon accounting frameworks and provide new insights for carbon balance assessment and management of hydropower systems.

The Tibetan Plateau developed through either stepwise or continuous outward expansion during the Cenozoic. However, its evolution prior to the Cenozoic remains poorly constrained. Understanding this earlier phase is crucial for reconstructing the complete orogenic evolution of the Tibetan Plateau. In this study, we present new insights from low-temperature thermochronometric analyses along an elevational transect in the Basu region of the eastern Tibet, combining Apatite/Zircon (U-Th)/He (AHe, ZHe). Our dataset reveals AHe ages ranging from 17.85 +/- 0.19 to 69.30 +/- 1.50 Ma and ZHe ages ranging between 126.17 +/- 3.21 and 187.59 +/- 5.0 Ma. Furthermore, QTQt thermal modeling identifies a pronounced Late Cretaceous-Early Eocene cooling phase (similar to 80-55 Ma), which we interpret as rapid exhumation and potential surface uplift in response to the northward subduction of the Neo-Tethyan oceanic lithosphere and convergence compression between India and Eurasia. This tectonic pulse was followed by markedly slower exhumation rates post- similar to 55 Ma. Our findings indicate that the proto-Tibetan Plateau, encompassing the central Tibetan Plateau's northern Lhasa and southern Qiangtang terranes, had already expanded to the Basu region by similar to 55 Ma. Regional evidence indicates that areas northwest of Basu had formed elevated topography prior to similar to 60 Ma, and regions to the southeast (including Markam, Gonjo and Weixi basins) had nearly reached their current elevations at similar to 40-35 Ma. This temporal-spatial pattern of cooling ages indicates the southeastward progression of regional exhumation and uplift from the Late Cretaceous through the Eocene, supporting the plateau stepwise expansion from the proto-Tibetan Plateau.

Earth’s surface oxygenation was a protracted, multi-step process. It is widely accepted that atmospheric O2 rose through three major steps, each closely linked to key evolutionary innovations. Recent advances, particularly in sulfate triple-oxygen-isotope records, now provide new constraints on the timing, tempo, and magnitude of atmospheric oxygenation. These data reveal a positive coupling between atmospheric and oceanic oxygenation on billion-year timescales, with stagewise rises in atmospheric O2 consistently preceding oceanic responses, whereas on shorter, million-year timescales, their redox states could diverge, exhibiting negative coupling. Oceanic redox evolution was also spatially and temporally heterogeneous, progressing from localized Archean oxygen oases (>3.0 Ga) to a globally oxygenated state by the Paleozoic (<0.41 Ga). Here we synthesize geochemical, sedimentological, and palaeobiological evidence to reconstruct this coupled and dynamic atmosphere-ocean oxygenation history and to reassess its timing, mechanisms, and ecological consequences. These deep-time perspectives illuminate the co-evolution of life and Earth’s surface environments and provide a conceptual framework for evaluating planetary habitability.

Dissolved organic matter (DOM) is the largest reservoir of reduced carbon in the modern ocean, playing a crucial role in the global carbon cycle and climate dynamics. However, there remains a lack of a proxy to directly track the composition and abundance of DOM in ancient oceans. In this study, we present a new approach for extracting and detecting carbonate-associated fluorescent dissolved organic matter (CAFDOM), aiming to establish it as a proxy for tracking DOM in ancient oceans. Our approach relies on three types of materials: (i) experimental samples with specifically defined properties, (ii) natural carbonate samples with known diagenetic histories (IODP core material, Marion Plateau), and (iii) well-preserved Ediacaran carbonate rocks from China. Following the protocol developed herein, the CAFDOM analysis of simulated carbonate samples shows good reproducibility for identifiable components, with relative standard deviations of less than 11% and average extraction rates exceeding 80%. Using fulvic acid as a natural model for DOM, carbonate precipitation experiments show that CAFDOM positively responds to solution DOM concentration in three distinct modes: (i) an exponential increase from zero with fulvic acid concentrations of 0-0.4 g/L; (ii) another exponential increase from zero with fulvic acid concentrations of 0.4-1.4 g/L; and (iii) a weak linear increase from a particular threshold with fulvic acid concentrations greater than 1.4 g/L. These modes are likely linked to critical shifts in the intermolecular forces of the DOM and its aggregation states during incorporation into the carbonate lattice. We propose that the abundance of DOM in ancient oceans can be constrained by combining the abundances with pairwise ratios of the CAFDOM components, and further evaluation and verification based on additional information of the investigated samples. Analysis of IODP core samples suggests that CAFDOM levels are likely influenced by the recrystallization from aragonite to calcite, authigenic carbonate formation, and replacement dolomitization. Based on the criteria established in this study, we analyzed Ediacaran carbonate samples (635-551 Myr) for CAFDOM. These data reveal significant variability in DOM in the Ediacaran marginal ocean, both in terms of concentration and fluorescent components. These findings are promising and suggest that, after conducting mineralogical characterization and screening for secondary alterations of sample material, CAFDOM can serve as an effective proxy for tracking DOM in ancient oceans.

The Great Ordovician Biodiversification Event (GOBE) was the largest radiation of marine life in the Phanerozoic, but its causes and consequences remain uncertain, in particular the extent to which environmental change drove biodiversity increase, or vice-versa. Here, we develop high-resolution chemostratigraphic and biodiversity records from South China to show that: the GOBE was initially accompanied by concurrent changes in diversity among plankton, nekton and benthos, suggesting coordinated development of ecological modes during the rapid expansion of marine ecosystems; the onset of the GOBE in the Early Ordovician preceded a major shift in delta 15N during the late Tremadocian to middle Darriwilian, suggesting that marine ecosystem changes drove nutrient cycle evolution in South China, and not the reverse; these changes were associated with an increase in organic matter burial that contributed to drawdown of atmospheric CO2 and long-term climatic cooling through the remainder of the Ordovician. These findings thus provide key insights into the interrelationships between the evolution of marine ecosystems, nutrient cycles, and environmental conditions during the early Paleozoic.

Apatite records ore genesis information in various hydrothermal mineral systems. They exhibit complex textures and diverse elemental and isotopic compositions over multiple generations. This study uses integrated petrographic, elemental, and isotopic data to analyze the properties, origin, and evolution of mineralizing fluids and ore-forming processes in a gold (Au) deposit with a complex tectonothermal history. The Zaozigou deposit is one of the top Au-producing deposits in China, the genesis of which has long been controversial. Based on cathodoluminescence, we classified the apatite crystals from the Zaozigou deposit into four groups (Ap1, Ap2, Ap3, and Ap4). Ap1 and Ap2 coexist with magmatic minerals, while Ap3 and Ap4 are associated with ore-related hydrothermal minerals. All four types exhibit homogeneous BSE intensity and distinct cathodoluminescence colors and elemental compositions (e.g., REE+Y, U, Th, Sr, Mn, Fe, Mg, Cl, F, and S). Strontium isotope data indicate low 87Sr/86Sr ratios (Ap1: 0.709854-0.711636, Ap2: 0.71024-0.711707) in pre-Au ore apatite. In contrast, syn-Au ore apatite shows high 87Sr/86Sr ratios (Ap3: 0.712022-0.713108, Ap4: 0.711656-0.71357). These alterations in elemental and Sr isotope compositions are indicative of modifications in fluid composition and nature, as well as the pivotal role played by metasomatic alteration in Au deposition. This study distinguishes between the initial magmatic and subsequent auriferous phases. Apatite chemistry and Sr isotope signature reveal that low-salinity, moderate-temperature carbonaceous crustal metamorphic fluids enriched in sulfur, strontium, and fluorine are responsible for Au deposition at the Zaozigou deposit through fluid-rock interactions. The auriferous fluids, Au, and associated metals are likely derived from crustal metamorphic systems, possibly from the West Qinling Paleozoic strata and/or South Qinling volcano-sedimentary basement rocks. The findings of this work suggest a supracrustal orogenic model for the Zaozigou Au deposit.

This study employs scientific methods of metallographic analysis, major and trace element analysis, and lead isotope analysis to systematically investigate the bronze fish excavated from the Weijiaya site in Baoji City, from the early Spring and Autumn period. Metallographic analysis reveals that all analyzed samples were cast, reflecting a unified casting technology tradition. Major element analysis revealed that all samples were leaded tin bronzes. Their alloy concentrations vary between groups, suggesting that the bronze fish were produced in different batches. Trace element analysis reveals a unified source of copper material, highly overlapping with Qin culture samples from Bianjiazhuang and Chencang District. Lead isotope analysis suggests that the lead materials were possibly sourced from Edong and Jiurui areas in the Yangtze River basin. However, the lead isotope data from CMK1 and M4 can be divided into two groups, indicating the use of different lead ores. Functional studies suggest that while M4 bronze fish served as coffin ornaments, the CMK1 bronze fish were likely used in funeral practices under the belief system of the Yellow Springs.

Geochemical data from sedimentary rocks are the primary source of information regarding Earth's surface evolution through time, including its air and water envelopes and interactions with life and deep Earth processes. The Sedimentary Geochemistry and Paleoenvironments Project (SGP) is a scientific consortium centered around open data and community-driven development of cyberinfrastructure tools and resources for sedimentary geochemistry and Earth history. Here we describe the SGP Phase 2 data release, which focused on incorporating Paleoproterozoic and Mesoproterozoic (2500–1000 million years ago) data and better accommodating carbonate data. This data release was built through the involvement of >200 researchers worldwide in academia, government, and industry, and provides the largest available public data resource for our user community in the academic fields of geochemistry, sedimentology, tectonics, paleontology, Earth history, and paleoclimate, as well as the petroleum and minerals industries. The dataset now encompasses 126,006 samples and 4,132,371 geochemical analyses. In addition to direct entry by SGP Team Members, we have ingested and incorporated datasets from the Geoscience Australia OZCHEM database, the Alberta Geological Survey, and the Deep-Time Marine Sedimentary Element Database (DM-SED) compilation. This paper details sampling in the Phase 2 dataset with respect to age, geography, lithology, and other geological characteristics, documents access via our search website and API, discusses possible issues and/or biases in the dataset that could impact analyses, describes plans for governance and stewardship of data from Indigenous lands, and serves as the citable reference paper for the data release.

The Ediacaran Period (635–539 Ma) witnessed the emergence of early animals, rapid oceanic oxygenation, and rising oceanic P availability. However, the relationships among these developments remain intensely debated. Here, we present high-resolution carbonate-associated phosphate (CAP) data from seven Ediacaran sections spanning diverse depositional environments across South China. Contrary to the modern ocean, our measurements reveal an inverted phosphorus (P) gradient, with lower P availability at depth. By integrating these data with a quantitative biogeochemical model, we show that increasing shallow-water P inputs drove enhanced productivity and bottom-water anoxia on continental shelves, while P-starved distal oceans became progressively oxygenated from the top downward, providing an oxygenated niche—a deep-ocean cradle—for early metazoan evolution. Our study establishes a conceptual framework linking nutrient dynamics, marine oxygenation, and evolutionary innovation in Earth’s early history. Carbonate associated phosphate indicates that Ediacaran oceans had more P in shallow waters but less in the deep sea, opposite to modern. A distal P shortage may have aided deep-water oxygenation and early animals.

Total organic carbon (TOC) is a key parameter for source-rock evaluation, but laboratory measurements are sparse and do not resolve continuous vertical variation. Conventional well logs provide continuous physical responses, whereas X-ray fluorescence (XRF) data add geochemical information. We evaluated the incremental value of combining these data sources using 58 depth-matched samples from the Yiwan-1 well in the Wangjiawan area, South China. Four well-log variables and six XRF variables selected within each training fold were evaluated with nine models under repeated 5-fold cross-validation (20 repeats). The fused SVR model performed best (RMSE = 0.789 ± 0.267; R = 0.912 ± 0.081). At the repetition level, the absolute RMSE reduction relative to logs alone was 0.430 (95% CI: 0.386–0.478), equivalent to 35.3% (Holm-adjusted p = 1.34 × 10−5). A 500-run permutation test that shuffled complete XRF sample rows gave an empirical p-value of 0.002. In a separate contiguous depth-block analysis with a 0.16 m exclusion buffer, the SVR RMSE decreased from 2.566 to 1.837, corresponding to an improvement of 28.4%, although the benefit was not retained by every linear model. Mo, V, Cr, Cd and Zn were selected in all Pearson-selection folds and had positive mean held-out permutation importance. The results support a complementary contribution from XRF data within this well while also showing that estimated accuracy depends on the validation design.

The episodic formation of sedimentary manganese (Mn) deposits is likely linked to variability in marine redox, yet the mechanisms governing their precipitation and their relationship to global oxygenation remain debated. Most Precambrian Mn deposits are dominated by rhodochrosite (MnCO3), complicating interpretations of their redox history. Here, we present new geochemical and isotopic constraints on Mn deposition at Chengkou area, one of the best-preserved Ediacaran Mn deposits, providing critical insights into regional or global redox dynamics. We present two new Re-Os ages of 581 +/- 14 Ma and 577 +/- 12 Ma, which within error overlap with the end of the Gaskiers glaciation and the Shuram negative carbon isotope excursion (SE). For the first time, we report epsilon 205Tl values (average of 5.1 +/- 0.6 & pertenk;) in Mn carbonate ores that are comparable to those of modern oxic deep-ocean sediments rich in Mn oxides. Combined with analyses of framboidal pyrite morphology, these results indicate that the Mn oxides precipitated under oxic bottom-water conditions before their reduction and transformation into Mn carbonates under anoxic conditions. This model contrasts with previous interpretations that involved a particle shuttling mechanism. Instead, multiple Mn oxide precipitation episodes at Chengkou reveal dynamic local redox oscillations. These findings provide critical insights into the environmental evolution of the Nanhua Basin. Furthermore, recurrent oxygenation pulses recorded from the post-Gaskiers glaciation to the SE may represent a prelude to widespread deep-ocean oxidation. Further Tlisotope investigations in coeval Mn deposits are necessary to better resolve the spatial extent of redox variability and its implications for global biogeochemical cycles.

The distribution of time among the stages and substages of the similar to 5-m.y.-long Early Triassic Epoch remains debated, with two competing chronological models: the short-Smithian timescale (similar to 0.5-1.2 m.y.), based mainly on radiometric dating of zircons, and the long-Smithian timescale (similar to 1.7-2.1 m.y.), based mainly on time-series analysis of various proxy records. Here, we evaluate these competing models based on a synthesis of biostratigraphy, chemostratigraphy, and cyclostratigraphy from three marine sections in South China: Qiyueshan, Jianshi, and Daxiakou. These sections yield similar records of carbonate carbon-isotopic (S13Ccarb) excursions and high-frequency variability in both S13Ccarb and carbonate-associated sulfate sulfur-isotope (S34SCAS) profiles, which together record five discrete cycles in the Dienerian Substage and six cycles in the Smithian Substage of the Lower Triassic. Cyclostratigraphic analysis of S34SCAS, informed by a biostratigraphically and radiometrically constrained geochronological framework, links high-frequency variation in the S34SCAS and S13Ccarb records to shorteccentricity (similar to 100-k.y.) orbital forcing, yielding duration estimates for the Dienerian and Smithian substages of similar to 500 +/- 100 k.y. and similar to 600 +/- 100 k.y., respectively, which is more consistent with the short-Smithian timescale. This finding illustrates the value of integrated studies that combine zircon U-Pb dating and astrochronology within a unified biostratigraphic and carbon-isotopic chemostratigraphic framework to establish a robust temporal framework for the Early Triassic.

The published early Permian age (281 +/- 2 Ma) of the lherzolite from the Tulaergen No. I mafic-ultramafic intrusion is similar to that of other Ni-Cu sulfide deposits in East Tianshan (southern margin of the Central Asian Orogenic Belt (CAOB)). In contrast, the published formation age of gabbro (300.5 +/- 3.2 Ma) is inconsistent with the age of the regional Ni-Cu sulfide mineralized gabbro. Furthermore, the published Re-Os isochron age of sulfides from the Tulaergen (265.6 +/- 9.2 Ma) disagrees with the zircon U-Pb age. Overall, the crystallization and mineralization ages of the Tulaergen are distinct from those of other magmatic sulfide deposits related to mafic-ultramafic intrusions in the region. Therefore, the question remains as to whether age is the key factor determining mineralization potential, or whether there are other critical factors that can be used to evaluate the ore-forming potential of mafic-ultramafic intrusions in East Tianshan. In this work, a precise SIMS zircon U-Pb age for the ore-bearing gabbro (282.9 +/- 2.4 Ma) is presented, along with an ore sulfide Re-Os age of 278.1 +/- 6.4 Ma, convincingly proving that all magmatic sulfide deposits in East Tianshan are concentrated around a Permian crystallization age. The Tulaergen gabbro epsilon Hf (t = 282.9 Ma) ranges from 9.3 to 15.5, and the delta O-18 values range from 4.9 parts per thousand to 6.3 parts per thousand. Meanwhile, the barren and mineralized gabbro in East Tianshan have distinct zircon epsilon Hf (t) and delta O-18 values, ranging from -3.6 similar to +17.2 and 4.1 parts per thousand to 11.9 parts per thousand, respectively. Depleted mantle-like positive epsilon Hf (t) and O isotopic signatures close to those of the mantle are the common signatures of magmatic sulfide - mineralized mafic-ultramafic rocks. At Tulaergen, amphibole grains show narrow ranges in crystallization temperature, pressure, and water content (1083 degrees C to 11,182 degrees C, 854 MPa to1750 MPa and 2.9 wt% to 4.7 wt%, respectively), consistent with the ranges seen in ore-bearing mafic-ultramafic rocks in East Tianshan. In contrast, barren and Fe-Ti oxide mineralized mafic-ultramafic rocks display a continuous amphibole crystallization trend across a range of temperature, pressure and water content. Large-scale sulfide crystallization and the sudden release of water may be the critical factors that disrupted the continuous crystallization of amphibole in magmatic sulfide deposits. Zircon age and Hf-O isotopes reflect a depleted mantle source and low degree of contamination relate to barren intrusions; concentrated amphibole compositions reveal fractional crystallization of silicate melt and large-scale sulfide segregation. Together, they provide a powerful tool for identifying the mineralization potential of mafic-ultramafic rocks and may enhance exploration strategies at the southern margin of the CAOB.

The mass-independent Mo isotope composition of the Bulk Silicate Earth (BSE) bears great potential to investigate the origin of the Earth's latest 10-20% planetary building blocks. However, currently different estimates for the Mo isotope composition of the BSE render constraints on the composition of late-stage accretionary materials difficult. To address this issue and to revisit the Mo isotope composition of the BSE, we report highprecision molybdenum isotope data for a comprehensive set of terrestrial molybdenites from different locations around the globe covering mineralization ages that extend from the Archean to the Phanerozoic. The molybdenite results are used to constrain the Mo isotope composition of the BSE as follows: c92Mo = 0.04 + 0.06, c94Mo = 0.03 + 0.03, c95Mo = 0.01 + 0.01, c97Mo = 0.02 + 0.02, c100Mo = 0.05 + 0.06 (n = 16, 95% confidence interval, relative to the NIST SRM 3134 Mo standard). In contrast to previous studies, no resolvable c94Mo and c95Mo anomalies were observed, suggesting a BSE composition with predominantly non-carbonaceous chondrite provenance. Considering the analytical uncertainties of our new BSE estimate and literature data for carbonaceous and non-carbonaceous meteorites, it remains a viable option that 12+10% of the present-day Mo budget in the BSE derives from carbonaceous meteorite material delivered during late-stage accretion. This amount of Mo is consistent with the fraction of Mo that was delivered to Earth during its final 0.5% of accretion by the late veneer.

The Middle Triassic Ordos Basin witnessed the earliest rehabilitation of complex lacustrine ecosystems after the end-Permian mass extinction (EPME). The specific challenges faced by freshwater ecosystems during this interval remain unclear, however, owing to the limited spatiotemporal coverage of integrated biogeochemical studies. Here, we combine high-resolution geochronology, mineralogical and multi-proxy geochemical data from the mid-Triassic Ordos Basin with temporal and spatial biogeochemical modelling to reconstruct lake redox structure and nutrient dynamics. Our results indicate that a transient increase in external sulfate input strengthened endogenous phosphorus recycling and eutrophication, promoting shoaling and intensification of a metastable sulfidic zone at mid-depths. This shoaling would have led to poisoning of benthic habitats, causing a collapse of the oldest known Mesozoic lacustrine ecosystem. We propose that sulfate loading prolonged anoxia and ecological stress by extending the residence time of phosphorus, a mechanism that may be relevant to deoxygenation events and resulting biocrises in both ancient and modern lacustrine ecosystems.

Geochemical anomaly detection plays a critical role in mineral exploration, yet conven-tional methods are often limited by compositional effects, sensitivity to outliers, and in-sufficient consideration of spatial relationships. To address these issues, this study pro-poses an integrated analytical framework that combines compositional data analysis and spatial statistics for robust geochemical anomaly identification. The framework incor-porates isometric log-ratio (ILR) transformation to eliminate the closure effect, robust principal component analysis (RPCA) to extract stable geochemical patterns, local indi-cators of spatial association (LISA) to characterize spatial clustering, and compositional balance analysis (CoBA) to enhance anomaly signals. The method is applied to the Barkol Lake area in the Eastern Tianshan, a key metallogenic belt within the Central Asian Orogenic Belt. The results reveal significant geochemical anomalies characterized by Cu-associated element assemblages (e.g., Cu–Ni–Cr), which are spatially correlated with major fault zones and volcanic–intrusive complexes. The identified anomalies show strong consistency with known mineral occurrences and delineate several prospective targets for copper polymetallic mineralization. Compared with conventional approaches, the proposed framework demonstrates improved robustness to outliers, enhanced sensi-tivity to weak anomalies, and better integration of compositional and spatial constraints. These advantages highlight its effectiveness for geochemical anomaly detection and mineral prospectivity mapping in complex geological settings.