Geoscience frontiers最新文献

{"title":"Phosphorite deposits: A promising unconventional resource for rare earth elements","authors":"Shamim A. Dar , V. Balaram , Parijat Roy , Akhtar R. Mir , Mohammad Javed , M. Siva Teja","doi":"10.1016/j.gsf.2025.102044","DOIUrl":"10.1016/j.gsf.2025.102044","url":null,"abstract":"<div><div>The green energy transition relies heavily on critical metals, such as rare earth elements (REEs). However, their reserves are primarily focused in a few countries, such as China, which accounts for approximately 70% of global production. Hence, several countries are currently looking for alternative resources for REEs. Alternative REE resources in the supply chain include recycling of e-waste, industrial waste like red mud and phosphogypsum, coal ash, mine tailings, ocean floor sediments, and even certain types of sedimentary deposits like phosphorites where REEs are present in lower concentrations but at larger volumes compared to primary ore deposits which are becoming targets by REEs industry. Currently, several studies are going on the development of eco-friendly REEs extraction technologies from phosphorite deposits. Consequently, advanced data analysis tools, such as Machine Learning (ML), are becoming increasingly important in mineral prospectivity and are rapidly gaining traction in the earth sciences. Phosphorite deposits are mainly used to manufacture fertilizers as these rocks are known for their significant phosphorus content. Moreover, these formations are considered a prospective resource of REEs. The different types of phosphorite deposits such as continental, seamount, and ore deposits worldwide reported concentrations of ∑REE upto 18,000 µg/g. Due to the augmented claim of REEs for various ultra-modern, and green technology applications that are required to switch over to a carbon–neutral environment, these phosphorite deposits have become an important target mostly because of their relatively higher content of REEs especially heavy rare earth elements (HREE). For example, Mississippian phosphorites reported ∑HREE 7,000 µg/g. To have a comprehensive understanding of the REEs potential of these phosphorite deposits which also include several Chinese phosphorite deposits, this study is undertaken to review the phosphorite deposits in the world and their REEs potential, in addition to some of the associated aspects such as applications and formation mechanisms for different types of phosphorite deposits such as igneous phosphate deposits, sedimentary phosphorite deposits, marine phosphorite deposits, cave phosphate deposits, and insular guano deposits. Other important aspects include their occurrences, types, geochemical characteristics, the REEs enrichment mechanisms, and various recovery methods adopted to recover REEs from different phosphorite deposits. The present review paper concludes that the recent studies highlight the global potential of phosphorite deposits to satisfy the increasing demand for REEs. Extracting REEs from phosphorite presents no significant technological or environmental difficulties, as long as radioactive elements are eliminated. In India, more comprehensive geological surveys, along with the advancement of new methods and evaluations, are required to locate phosphorite deposits with high conc","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 3","pages":"Article 102044"},"PeriodicalIF":8.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143895134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Zinc and cadmium isotope signatures: Insights into ore genesis and exploration strategies at the Xiaohongshilazi Pb-Zn-(Ag) deposit, Northeast China","authors":"Huchao Ma ,&nbsp;Da Wang ,&nbsp;Ryan Mathur ,&nbsp;Gaotian Wang ,&nbsp;Feng Bai","doi":"10.1016/j.gsf.2025.102054","DOIUrl":"10.1016/j.gsf.2025.102054","url":null,"abstract":"<div><div>The Jizhong–Yanbian Cu-Mo-Au-Pb-Zn polymetallic metallogenic belt is a major nonferrous and precious metal resource base in Northeastern China. The genesis of ore deposits in this district has remained controversial. To constrain ore genetic models and provide information for exploration, we conducted precise Zn-Cd isotopic measurements on sphalerite and galena. The <em>δ</em>⁶⁶Zn_AA–ETH values of galena and sphalerite range from −0.07‰ to 0.03‰ and −0.68‰ to −0.12‰, respectively; and their <em>δ</em>^114/110Cd_{NIST SRM 3108} values vary from −0.96‰ to 3.83‰ and −0.63‰ to 0.77‰, respectively. Our study suggests that the Xiaohongshilazi Pb-Zn-(Ag) deposit should be classified as a Mississippi Valley Type (MVT)-like deposit, because both its geological, sulfide trace elemental, and S-Pb-Fe-Zn-Cd isotopic characteristics are similar to those of the typical MVT deposit, except for the differences of the wall rocks. Rayleigh fractionation during sphalerite precipitation is identified as the primary mechanism for Zn-Cd isotopic variations, which is validated by the Zn-Cd fractionation models from 100 °C to 250 °C. Finally, we propose an ore prospecting model based on migration pathways of ore-forming fluid and the Zn isotopic fractionation model of sphalerite under 100 °C. This model indicates potential resources undiscovered at shallow/peripheral and deep zones of current mining level in both the Eastern and Western Ore Block, with parts of the potential resources having been corroborated by recent drilling. Despite the complexity of mineralization, processes, this study provides new insights into the application of Zn-Cd isotopes in understanding ore genesis and guiding mineral exploration in similar contexts.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 4","pages":"Article 102054"},"PeriodicalIF":8.5,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143882621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"How digitalization, renewable energy, and natural resources shape environmental excellence? Evidence from China using a Quantile-on-Quantile framework","authors":"Wei Chen ,&nbsp;Muhammad Usman ,&nbsp;Rakhshanda Kousar ,&nbsp;Paiman Ahmad","doi":"10.1016/j.gsf.2025.102055","DOIUrl":"10.1016/j.gsf.2025.102055","url":null,"abstract":"<div><div>Natural resources, green energy, and sustainable development are closely linked with concepts that carry mutual goals to endorse social equity, economic prosperity, and ecological stability while curtailing the harmful influence on the globe. However, the recognition of the Sustainable Development Goals (SDG-7, SDG-13) is closely entangled with digital economy. In this pursuit, this study scrutinizes the effect of digitalization, renewable energy, and natural resources on the ecological footprint in China from 1990Q1-2022Q4. The empirical analyses are carried out by employing the Quantile-on-Quantile regression, and cross-quantile and partial cross-quantile correlation approaches to inspect the tail dependence of model parameters. The empirical outcomes highlight how China’s environmental quality is influenced by exogenous variables, including digitalization index, renewable energy consumption, and natural resources. Digitalization has adverse impact on the ecological footprint in lower quantiles, while insignificant in higher quantiles. Moreover, a strong adverse association exists between ecological footprint and renewable energy, which syndicate all the quantiles of renewable energy with linking over lower to middle quantiles and weak in higher quantiles of ecological footprint. Besides, the estimated analysis discloses nuanced dependencies across various quantiles. Similarly, it can be found that the strong negative effect of natural resources on ecological footprint in initial quantiles, moderate in middle quantiles, and less positive effect in higher quantiles. By explaining these dynamics, the current study offers valuable intuitions designed at controlling China toward its dual-carbon target and encouraging the development of a sustainable digital and green economy and thereby, continuing towards achieving SDG-7, and SDG-13 objectives.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 4","pages":"Article 102055"},"PeriodicalIF":8.5,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143887911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formation of the rare Xiaoqinling Au-Mo province: Timings and geodynamic triggers","authors":"Panfei Sun ,&nbsp;Zhao Liu ,&nbsp;Lin Yang ,&nbsp;Qingfei Wang ,&nbsp;David I. Groves ,&nbsp;Chao Li ,&nbsp;Huajian Li ,&nbsp;Chaoyi Dong ,&nbsp;Zhiqiang Xue ,&nbsp;Zhongming Li ,&nbsp;Jun Deng","doi":"10.1016/j.gsf.2025.102052","DOIUrl":"10.1016/j.gsf.2025.102052","url":null,"abstract":"<div><div>The timings and geodynamic controls of Mo, Au, and Au-Mo deposits in the Xiaoqinling Orogen (&gt; 630 t Au and 115, 000 t Mo), a rare Au-Mo province globally, are addressed by a combination of mineral parageneses, crystalline mineralogy, geochemistry, and Re-Os and U-Pb geochronology in the Dahu, Qinnan, and Yangzhaiyu deposits. The Xiaoqinling Orogen comprises an E-W-trending fold and thrust system with repeated structural reactivation and the Mo or Au orebodies in these deposits are dominantly controlled by E–W-trending and NW–SE-trending shear zones. Molybdenum mineralization related to K-feldspar alteration comprises early molybdenite, pyrite, rutile, and monazite within gray quartz veins plus late molybdenite and pyrite within white quartz veins in the Dahu and Qinnan Au-Mo deposits. Early and late Au mineralization events have similar mineral assemblages of pyrite, native gold ± Au-Ag-Te minerals, rutile, and monazite associated with quartz-sericite alteration at Yangzhaiyu. The early disseminated molybdenite is characterized by rhombohedral polytype and oscillatory Re zoning, in contrast to the late molybdenite with a coexistence of rhombohedral and hexagonal polytypes and irregularly distributed Re. The early molybdenite has a Re-Os isochron age of 222.5 ± 1.3 Ma, compatible with a monazite U-Pb age of 224 ± 6.1 Ma, whereas late molybdenite provides a Re-Os isochron age of 185.0 ± 12 Ma, with the implication that the 3R-polytype molybdenite with oscillatory Re zoning is more suitable for high-precision dating. The early and late Au mineralization have a pyrite Re-Os age of 202.0 ± 5.9 Ma and U-Pb age of 124.0 ± 1.3 Ma, respectively. In accordance with its complex geodynamic setting, geological and geochronological studies record a complicated 100-million-year mineralization history with multiple magmatic-hydrothermal Mo and orogenic Au mineralization events that formed within a structural framework of multiply reactivated shear zones.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 4","pages":"Article 102052"},"PeriodicalIF":8.5,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143876850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stable chromium isotope fractionation during melt percolation: Implications for chromium isotopic heterogeneity in the mantle","authors":"Haibo Ma ,&nbsp;Li-Juan Xu ,&nbsp;Yu-Wen Su ,&nbsp;Chunyang Liu ,&nbsp;Sheng-Ao Liu ,&nbsp;Jia Liu ,&nbsp;Zezhou Wang ,&nbsp;Guochun Zhao","doi":"10.1016/j.gsf.2025.102049","DOIUrl":"10.1016/j.gsf.2025.102049","url":null,"abstract":"<div><div>To investigate the stable chromium (Cr) isotope variations during melt percolation in the mantle, we analyzed the Cr isotopic compositions of fresh ultramafic rocks from the Balmuccia and Baldissero peridotite massifs located in the Italian Alps. These massifs represent fragments of the subcontinental lithospheric mantle. The samples collected included lherzolites, harzburgites, dunites, and pyroxenites. Lherzolites, formed through 5%–15% fractional melting of a primitive mantle source, exhibited <em>δ</em>⁵³Cr values ranging from −0.13‰ ± 0.03‰ to −0.03‰ ± 0.03‰. These values correlated negatively with Al₂O₃ content, suggesting that partial melting induces Cr isotopic fractionation between the melts and residual peridotites. Harzburgites and dunites, influenced by the silicate melt percolation, displayed distinct <em>δ</em>⁵³Cr values. Notably, dunites not spatially associated with the pyroxenite veins exhibited slightly elevated <em>δ</em>⁵³Cr values (−0.05‰ ± 0.03‰ to 0.10‰ ± 0.03‰) relative to lherzolites. This difference likely resulted from pyroxene dissolution and olivine precipitation during melt percolation processes. However, one dunite sample in direct contact with pyroxenite veins showed lower <em>δ</em>⁵³Cr values (−0.26‰ ± 0.03‰), possibly owing to the kinetic effects during silicate melt percolation. Pyroxenites are formed through the interaction of basaltic melts with the surrounding peridotite via a metasomatic reaction or crystallization in a vein. Most of their <em>δ</em>⁵³Cr values (−0.26‰ ± 0.03‰ to −0.13‰ ± 0.03‰) are positively correlated with MgO contents, suggesting that they were influenced by magmatic differentiation. However, two subsamples from a single clinopyroxenite vein exhibit anomalously low <em>δ</em>⁵³Cr values (−0.30‰ ± 0.03‰ and −0.43‰ ± 0.03‰), which are attributed to kinetic isotopic fractionation during melt-percolation processes. Our findings suggest that melt percolation processes in the mantle contribute to the Cr isotopic heterogeneity observed within the Earth’s mantle.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 4","pages":"Article 102049"},"PeriodicalIF":8.5,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143870241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Complex cross-regional landslide susceptibility mapping by multi-source domain transfer learning","authors":"Yan Su ,&nbsp;Jiayuan Fu ,&nbsp;Xiaohe Lai ,&nbsp;Chuan Lin ,&nbsp;Lvyun Zhu ,&nbsp;Xiudong Xie ,&nbsp;Jun Jiang ,&nbsp;Yaoxin Chen ,&nbsp;Jingyu Huang ,&nbsp;Wenhong Huang","doi":"10.1016/j.gsf.2025.102053","DOIUrl":"10.1016/j.gsf.2025.102053","url":null,"abstract":"<div><div>Landslide susceptibility evaluation plays an important role in disaster prevention and reduction. Feature-based transfer learning (TL) is an effective method for solving landslide susceptibility mapping (LSM) in target regions with no available samples. However, as the study area expands, the distribution of landslide types and triggering mechanisms becomes more diverse, leading to performance degradation in models relying on landslide evaluation knowledge from a single source domain due to domain feature shift. To address this, this study proposes a Multi-source Domain Adaptation Convolutional Neural Network (MDACNN), which combines the landslide prediction knowledge learned from two source domains to perform cross-regional LSM in complex large-scale areas. The method is validated through case studies in three regions located in southeastern coastal China and compared with single-source domain TL models (TCA-based models). The results demonstrate that MDACNN effectively integrates transfer knowledge from multiple source domains to learn diverse landslide-triggering mechanisms, thereby significantly reducing prediction bias inherent to single-source domain TL models, achieving an average improvement of 16.58% across all metrics. Moreover, the landslide susceptibility maps generated by MDACNN accurately quantify the spatial distribution of landslide risks in the target area, providing a powerful scientific and technological tool for landslide disaster management and prevention.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 4","pages":"Article 102053"},"PeriodicalIF":8.5,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143855340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formation of late-stage passive-roof duplexes in fold-and-thrust belts: Thrusting sequence and thermochronologic constraints from the Northern Apennines (Italy)","authors":"Marco Bonini ,&nbsp;Daniele Maestrelli ,&nbsp;Domenico Montanari ,&nbsp;Federico Sani ,&nbsp;Maria Laura Balestrieri","doi":"10.1016/j.gsf.2025.102048","DOIUrl":"10.1016/j.gsf.2025.102048","url":null,"abstract":"<div><div>Passive-roof duplexes accommodate shortening at the mountain front of many fold-and-thrust belts worldwide. These structures typically manifest at the surface by hinterland-verging backthrusts that decouple thin-skinned thrust sheets from underlying foreland-verging duplexes. Although the main factors controlling the development of passive-roof duplexes have mostly been identified, some of their intrinsic characteristics are still poorly defined. These relate to their spatio-temporal relationships to thrust faults located further inland in orogens, and their ability to transport younger rocks over older ones. This study explores these issues in the Casentino-Romagna axial sector of the Northern Apennines, which expose regional forethrusts and backthrusts. Detailed field mapping and analysis of superposed tectonic structures were integrated with apatite fission-track dating for constraining the timing of rock exhumation and correlated tectonic events. Collectively, the results have allowed us to interpret the evolution of the study area in terms of two main deformation stages. Specifically, a first, long phase (D₁) progressed from NE-directed, in-sequence thrusting (∼18 to ∼10–9 Ma) to late out-of-sequence thrusting (∼8–5 Ma). A successive deformation phase, that we refer to as D₂ (∼4–2 Ma), consisted of backthrusts and associated folds that were ubiquitous and systematically overprinted onto the foreland-verging D₁ structures. Such retrovergent structures identify a late deformation phase dominated by the development of passive-roof duplexes that propagated hinterlandward into the orogen up to beyond the primary watershed ridge. Orogen-scale processes controlled the evolution of forelandward D₁-phase thrusts, although late erosion could have played a major role by bringing the Apennine thrust wedge toward an undercritical state. The latter conditions could have contributed to keeping the out-of-sequence thrusts active, and eventually promoted the development of the D₂ passive-roof duplexes.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 4","pages":"Article 102048"},"PeriodicalIF":8.5,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143859590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formation of the giant Cretaceous Jiaodong-type orogenic gold province of the North China Craton: A consequence of lithospheric multi-layer reworking","authors":"Qingfei Wang ,&nbsp;Hesen Zhao ,&nbsp;Lin Yang ,&nbsp;David I. Groves ,&nbsp;Jilong Han ,&nbsp;Kunfeng Qiu ,&nbsp;Dapeng Li ,&nbsp;Zhao Liu ,&nbsp;Rui Zhao ,&nbsp;Jun Deng","doi":"10.1016/j.gsf.2025.102047","DOIUrl":"10.1016/j.gsf.2025.102047","url":null,"abstract":"<div><div>The Cretaceous gold deposits along the margins of the North China Craton (NCC), which formed in a craton destruction setting, display geological characteristics similar to traditional orogenic gold deposits typically associated with accretionary orogeny. These deposits, known as Jiaodong-type gold deposits, have attracted considerable attention. However, the lithospheric controls and formation mechanisms of these deposits remain unclear, as they cannot be fully explained by the supracrustal metamorphic genetic model commonly applied to classic orogenic gold deposits. In this study, the compiled S-Hg-Pb isotope ratios of gold deposits on different NCC margins display compatible variations to the Sr-Nd-Hg isotope ratios of mafic dikes spatial-temporally associated with the deposits. This implies that mantle lithosphere, metasomatized by variable proportions of oceanic and continental crust, was the source for both gold deposits and mafic dikes. Increase of oxygen fugacity and zircon <em>ε</em>Hf(<em>t</em>) from pre- to <em>syn</em>-gold granites suggests continuous basic magma underplating, which could induce concentrations of Au-rich sulfides and contribute additional Au to auriferous CO₂-rich fluids derived from metasomatized mantle lithosphere and basic magma. Localization of gold deposits was controlled by craton-margin sinistral shearing induced by clockwise rotation of the craton coincident with distal emplacement of metamorphic core complexes. Thus, the Cretaceous Jiaodong-type orogenic gold deposits were derived from fertilized mantle lithosphere through such crust-mantle processes within a lithosphere thinning background.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 3","pages":"Article 102047"},"PeriodicalIF":8.5,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental heating of CI chondrite: Empirical constraints on the evolution of micrometeorite O-isotopes during atmospheric entry","authors":"N.G. Rudraswami ,&nbsp;M.D. Suttle ,&nbsp;Yves Marrocchi ,&nbsp;M. Pandey ,&nbsp;Laurent Tissandier ,&nbsp;Johan Villeneuve","doi":"10.1016/j.gsf.2025.102046","DOIUrl":"10.1016/j.gsf.2025.102046","url":null,"abstract":"<div><div>Extraterrestrial dust exhibits a wide range of textural, chemical and oxygen isotopic compositions due to the heterogeneity of their precursors and modification during atmospheric entry. Experimental heating provides an opportunity to investigate the relationship between thermal processing and micrometeorite composition for a known precursor material. We conducted experiments to simulate the atmospheric entry of micrometeorites (MMs) using controlled, short-duration (10–50 s) flash heating (400–1600 °C) of CI chondrite chips (&lt;1500 µm) in atmospheric air (1 bar, 21% O₂) combined with microanalysis (textures, chemical and isotopic compositions) of the experimental products. The heated chips closely resemble natural samples, with materials similar to unmelted MMs, partially melted (scoriaceous) MMs and fully melted cosmic spherules produced. We reproduced several key features such as dehydration cracks, magnetite rims, volatile gas release, vesicle formation and coalescence, melting and quench cooling. Our parameter space allows for discriminating peak temperature and heating duration effects. Peak temperature is the first-order control on MM mineralogy, while heating duration controls vesicle coalescence and homogenization. When compared against previous heating experiments, our data demonstrates that CI chondrite dust is more thermally resistant, relative to CM chondrite dust, by approximately +200 °C. The 207 measurement of O-isotopes allows, for the first time, petrographic effects (such as volatile degassing and melting) to be correlated against bulk O-isotope evolution. Our results demonstrate findings applicable to CI chondrites and potentially to all fine-grained hydrated carbonaceous chondrite dust grains: (1) O-isotope variations arising during sub-solidus heating are dominated by the release of water from phyllosilicates, forcing the residual MM composition towards its anhydrous precursor composition. (2) Oxygen isotope compositions undergo the most significant changes at supra-solidus temperatures. As previously demonstrated and now empirically confirmed, most of these changes are driven by a mass-dependent fractionation effect caused by evaporation, which shifts residual rock compositions toward heavier values. Mixing with atmospheric air alters compositions toward the terrestrial fractionation line. Notably, these two processes do not begin simultaneously. Our data indicate that at 1200 °C, isotopic evolution is dominated by evaporative mass loss. However, at higher temperatures (1400–1600 °C), both pronounced evaporation and mixing with atmospheric oxygen become active, resulting in a more complex isotopic signature. (3) The total change in Δ¹⁷O during heating up to 1600 °C is &lt; 3‰ and in most scenarios &lt; 2‰.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 3","pages":"Article 102046"},"PeriodicalIF":8.5,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment of trace elements distribution and sources from snowpits in the Lambert Glacier region, coastal East Antarctica","authors":"Yalalt Nyamgerel ,&nbsp;Soon Do Hur ,&nbsp;Tseren-Ochir Soyol-Erdene ,&nbsp;Cunde Xiao ,&nbsp;Hyejung Jung ,&nbsp;Jeonghoon Lee","doi":"10.1016/j.gsf.2025.102045","DOIUrl":"10.1016/j.gsf.2025.102045","url":null,"abstract":"<div><div>The measurement of trace elements in Antarctic snow is crucial for understanding historical atmospheric geochemical changes and circulation patterns. However, studies on their spatial distributions remain limited, particularly those evaluating multiple metals across several snowpits, making interpretation challenging. This study investigates the distributions and sources of trace elements—including Cd, Ba, Pb, U, Bi, V, Mn, Fe, Cu, Zn, and As—across four snowpits in the Lambert Glacier Basin, East Antarctica. The trace elements exhibit site-, element-, and season-dependent variations, with higher concentrations observed at inland sites. In contrast, <em>δ</em>¹⁸O and ion concentrations decrease with increasing distance from the coast and elevation, underscoring the influence of marine emissions. Crustal sources primarily contributed to Ba, U, V, Mn, and Fe, while non-crustal sources predominantly contributed to Cd, Bi, Zn, Pb, Cu, and As. Positive matrix factorization (PMF) analysis indicates that trace element concentrations in Pits 2 and 3 are influenced by both crustal and non-crustal sources, while Pit 4 reflects a mixed-source influence. Pit 1 (coastal site) also indicates the mixed sources with influence of a highly dynamic marine climate and environment. The PMF results reveal similarities in emission sources and atmospheric transport patterns across the snowpits, facilitating a more comprehensive interpretation of longer ice core records. Overall, this study provides valuable insights into trace element distributions and enhances our understanding of past environmental and climatic conditions.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 3","pages":"Article 102045"},"PeriodicalIF":8.5,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143838017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}