Taian Lu, Thomas S. Bianchi, Michael R. Shields, Naishuang Bi, Xiao Wu, Limin Hu, Xiaoyan Ning, Houjie Wang
Biospheric organic carbon (OC) burial and petrogenic OC oxidation are fundamental controls in the regulation of global CO2 concentrations. River deltas are among the largest OC sinks in the ocean, storing substantial amounts of terrestrial OC originating from both the biosphere and lithosphere. However, the extent of biospheric and petrogenic OC storage in deltas remains poorly understood. Here, we quantified biospheric and petrogenic OC burial rates in a dynamic river delta, the Yellow River Delta, using geomorphology and carbon isotopic analyses. The Yellow River Delta is characterized by high burial rates of petrogenic OC (109 ± 27 g m−2 yr−1) and pre-aged soil OC (107 ± 27 g m−2 yr−1), followed by terrestrial modern OC (87 ± 21 g m−2 yr−1) and marine OC (48 ± 16 g m−2 yr−1). The deltaic biospheric OC burial rate (242 g m−2 yr−1) is up to 70 times higher than the global average in marginal seas. By analyzing biospheric and petrogenic OC burial rates and fluxes in global deltas and marginal seas, we highlight the critical role of deltas as major sinks for biospheric OC. This study underscores the importance of distinguishing between biospheric and petrogenic OC when assessing carbon sinks to better constrain their influence on atmospheric CO2 levels.
生物圈有机碳（OC）埋藏和成岩OC氧化是全球CO2浓度调节的基本控制因素。河流三角洲是海洋中最大的OC汇之一，储存了大量来自生物圈和岩石圈的陆地OC。然而，三角洲生物圈和岩石成因的OC储存程度仍然知之甚少。本文采用地貌学和碳同位素分析方法，对黄河三角洲动态河流三角洲的生物圈和岩石成因OC埋藏率进行了量化。黄河三角洲以成岩OC（109±27 g m−2 yr−1）和预熟土壤OC（107±27 g m−2 yr−1）埋藏率高为特征，其次是陆相现代OC（87±21 g m−2 yr−1）和海相OC（48±16 g m−2 yr−1）。在边缘海域，三角洲生物圈OC埋藏率为242 g m−2 yr−1，是全球平均水平的70倍。通过分析全球三角洲和边缘海的生物圈和岩源OC埋藏速率和通量，我们强调了三角洲作为生物圈OC主要汇的关键作用。这项研究强调了在评估碳汇时区分生物圈和岩石成因OC的重要性，以更好地限制它们对大气二氧化碳水平的影响。
{"title":"Key role of river deltas in carbon sequestration through biospheric organic carbon burial","authors":"Taian Lu, Thomas S. Bianchi, Michael R. Shields, Naishuang Bi, Xiao Wu, Limin Hu, Xiaoyan Ning, Houjie Wang","doi":"10.1130/g53573.1","DOIUrl":"https://doi.org/10.1130/g53573.1","url":null,"abstract":"Biospheric organic carbon (OC) burial and petrogenic OC oxidation are fundamental controls in the regulation of global CO2 concentrations. River deltas are among the largest OC sinks in the ocean, storing substantial amounts of terrestrial OC originating from both the biosphere and lithosphere. However, the extent of biospheric and petrogenic OC storage in deltas remains poorly understood. Here, we quantified biospheric and petrogenic OC burial rates in a dynamic river delta, the Yellow River Delta, using geomorphology and carbon isotopic analyses. The Yellow River Delta is characterized by high burial rates of petrogenic OC (109 ± 27 g m−2 yr−1) and pre-aged soil OC (107 ± 27 g m−2 yr−1), followed by terrestrial modern OC (87 ± 21 g m−2 yr−1) and marine OC (48 ± 16 g m−2 yr−1). The deltaic biospheric OC burial rate (242 g m−2 yr−1) is up to 70 times higher than the global average in marginal seas. By analyzing biospheric and petrogenic OC burial rates and fluxes in global deltas and marginal seas, we highlight the critical role of deltas as major sinks for biospheric OC. This study underscores the importance of distinguishing between biospheric and petrogenic OC when assessing carbon sinks to better constrain their influence on atmospheric CO2 levels.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"37 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145396644","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}
Funing Sun, Jiajie Zhang, Xiaohua Teng, Genming Luo, Chunlian Wang, Zuwei Feng, Richard D. Pancost, Shucheng Xie
Inland aquatic ecosystems are the largest natural source of greenhouse gas methane (CH4) release to the atmosphere. Although the temperature dependence of CH4 dynamics in freshwater systems is well documented, CH4 cycling in salt-rich inland waters and its response to rapid global warming remain poorly understood, particularly during past greenhouse climates. Here, we use the carbon isotopic composition of lipid biomarkers to reconstruct CH4 cycling in a saline lake during the Paleocene−Eocene Thermal Maximum (PETM; ca. 56 Ma), a geological analog for future warming. Our results suggest that, in contrast to the high temperature sensitivity reported for contemporaneous freshwater wetlands, microbial CH4 cycling in the saline lacustrine system of the Jianghan Basin (central China) showed a muted response to rapid greenhouse warming during the PETM. The high salinity and sulfate concentrations, combined with limited available substrates, may have inhibited methanogenesis and subsequent CH4 emissions at the ecosystem level. Our findings suggest that widespread salinization could restrict CH4 dynamics in inland aquatic ecosystems and affect large-scale greenhouse gas feedbacks to climate warming.
{"title":"Salinity limited methane cycling in lacustrine settings during the Paleocene−Eocene Thermal Maximum","authors":"Funing Sun, Jiajie Zhang, Xiaohua Teng, Genming Luo, Chunlian Wang, Zuwei Feng, Richard D. Pancost, Shucheng Xie","doi":"10.1130/g53790.1","DOIUrl":"https://doi.org/10.1130/g53790.1","url":null,"abstract":"Inland aquatic ecosystems are the largest natural source of greenhouse gas methane (CH4) release to the atmosphere. Although the temperature dependence of CH4 dynamics in freshwater systems is well documented, CH4 cycling in salt-rich inland waters and its response to rapid global warming remain poorly understood, particularly during past greenhouse climates. Here, we use the carbon isotopic composition of lipid biomarkers to reconstruct CH4 cycling in a saline lake during the Paleocene−Eocene Thermal Maximum (PETM; ca. 56 Ma), a geological analog for future warming. Our results suggest that, in contrast to the high temperature sensitivity reported for contemporaneous freshwater wetlands, microbial CH4 cycling in the saline lacustrine system of the Jianghan Basin (central China) showed a muted response to rapid greenhouse warming during the PETM. The high salinity and sulfate concentrations, combined with limited available substrates, may have inhibited methanogenesis and subsequent CH4 emissions at the ecosystem level. Our findings suggest that widespread salinization could restrict CH4 dynamics in inland aquatic ecosystems and affect large-scale greenhouse gas feedbacks to climate warming.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"64 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145397815","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}
Thibault Duretz, Julie Tugend, Geoffroy Mohn, Stefan M. Schmalholz
Continental lithosphere extension leads to necking and breakup, forming conjugate rifted margins that vary from symmetric to asymmetric morphologies. Although such differences are commonly linked to variations in initial lithospheric rheology, along-strike transitions between symmetric and asymmetric margins within single rift systems point to additional controlling factors. Structural inheritance, causing mechanical anisotropy in the continental lithosphere, is commonly suggested to influence rift evolution. Here we present novel geodynamic models of lithospheric extension incorporating inherited mechanical anisotropy using a transversely isotropic visco-plastic rheology coupled to the director vector approach. By systematically varying anisotropy strength and initial fabric orientation, we demonstrate that mechanical anisotropy alone can explain the transition from symmetric to asymmetric rifting. In our models, isotropic materials favor symmetric rifting dominated by pure shear deformation, while anisotropic materials promote asymmetric rifting driven primarily by simple shear. This transition occurs at low initial fabric angles and moderate anisotropy strengths. Our results offer a novel and robust mechanism for the formation of both symmetric and asymmetric conjugate margins and suggest that along-strike variations in structural inheritance—and thus mechanical anisotropy—can produce contrasting deformation styles within a single rift system. These findings highlight the critical role of mechanical anisotropy in shaping rifted margins and influencing the tectonic evolution of continental lithosphere.
{"title":"Symmetry versus asymmetry of rifted margins: The role of mechanical anisotropy","authors":"Thibault Duretz, Julie Tugend, Geoffroy Mohn, Stefan M. Schmalholz","doi":"10.1130/g53383.1","DOIUrl":"https://doi.org/10.1130/g53383.1","url":null,"abstract":"Continental lithosphere extension leads to necking and breakup, forming conjugate rifted margins that vary from symmetric to asymmetric morphologies. Although such differences are commonly linked to variations in initial lithospheric rheology, along-strike transitions between symmetric and asymmetric margins within single rift systems point to additional controlling factors. Structural inheritance, causing mechanical anisotropy in the continental lithosphere, is commonly suggested to influence rift evolution. Here we present novel geodynamic models of lithospheric extension incorporating inherited mechanical anisotropy using a transversely isotropic visco-plastic rheology coupled to the director vector approach. By systematically varying anisotropy strength and initial fabric orientation, we demonstrate that mechanical anisotropy alone can explain the transition from symmetric to asymmetric rifting. In our models, isotropic materials favor symmetric rifting dominated by pure shear deformation, while anisotropic materials promote asymmetric rifting driven primarily by simple shear. This transition occurs at low initial fabric angles and moderate anisotropy strengths. Our results offer a novel and robust mechanism for the formation of both symmetric and asymmetric conjugate margins and suggest that along-strike variations in structural inheritance—and thus mechanical anisotropy—can produce contrasting deformation styles within a single rift system. These findings highlight the critical role of mechanical anisotropy in shaping rifted margins and influencing the tectonic evolution of continental lithosphere.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"80 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145397820","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}
Mauro Rosi, Stefano Caliro, Giovanni Chiodini, Mauro A. Di Vito, Carmine Minopoli, Flora Giudicepietro
The Campi Flegrei caldera, west of Naples, Italy, is currently experiencing volcanic unrest, a process that started 75 years ago. The magmatic origin of past uplift crises has been questioned by studies based on 14C data from marine organisms, suggesting three rapid uplifts; only the last, in the fifteenth century, was followed by the Monte Nuovo eruption (1538 CE). New 14C dating and water composition analyses from the thermal spring in the Roman Macellum of Pozzuoli (Serapeo) show that the two supposed non-eruptive medieval unrest phases are unreliable, because they are based on too-old ages due to absorption of deep 14C-depleted CO2 by marine fauna. The implication of this finding is that the current unrest has a high probability of being linked to the resumption of magma supply to the shallow plumbing system of the caldera, and that this process could result in a renewal of volcanic activity in the area.
{"title":"Unveiling \"too-old\" radiocarbon ages at Serapeo (Pozzuoli) enhances understanding of the present unrest crisis at Campi Flegrei caldera, Italy","authors":"Mauro Rosi, Stefano Caliro, Giovanni Chiodini, Mauro A. Di Vito, Carmine Minopoli, Flora Giudicepietro","doi":"10.1130/g53578.1","DOIUrl":"https://doi.org/10.1130/g53578.1","url":null,"abstract":"The Campi Flegrei caldera, west of Naples, Italy, is currently experiencing volcanic unrest, a process that started 75 years ago. The magmatic origin of past uplift crises has been questioned by studies based on 14C data from marine organisms, suggesting three rapid uplifts; only the last, in the fifteenth century, was followed by the Monte Nuovo eruption (1538 CE). New 14C dating and water composition analyses from the thermal spring in the Roman Macellum of Pozzuoli (Serapeo) show that the two supposed non-eruptive medieval unrest phases are unreliable, because they are based on too-old ages due to absorption of deep 14C-depleted CO2 by marine fauna. The implication of this finding is that the current unrest has a high probability of being linked to the resumption of magma supply to the shallow plumbing system of the caldera, and that this process could result in a renewal of volcanic activity in the area.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"131 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145311578","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}
M. Colin Marvin, Michael Hasson, Vittorio Colicci, Raisha Abubo, Mathieu G.A. Lapôtre
Sedimentary rocks archive the history of Earth’s surface. However, alteration by diagenesis, weathering, deformation, and metamorphism makes interpretating Earth’s earliest environments challenging and ambiguous. We show that detrital zircon grains preserve an unaltered account of transport history, even in billion-year-old sedimentary rocks. We systematically document microscopic features on modern zircon sand grains (“microtextures”) from three continental environments—aeolian, fluvial, and beach foreshore—in modern sediment and Phanerozoic sedimentary rocks of independently known transport history. Our statistical analysis reveals that microtextural assemblages can be used to diagnose transport settings in detrital zircon grains, including recycled grains. Finally, we demonstrate the applicability of zircon microtextural analyses to Precambrian metasedimentary rocks of independently but poorly constrained transport histories. Detrital zircon grains preserve an untapped account of early surface environments, expanding the applicability of sand microtextural analyses to the first 90% of Earth’s history.
{"title":"Microtextural analyses of detrital zircon for paleoenvironmental interpretations of metasedimentary rocks","authors":"M. Colin Marvin, Michael Hasson, Vittorio Colicci, Raisha Abubo, Mathieu G.A. Lapôtre","doi":"10.1130/g53712.1","DOIUrl":"https://doi.org/10.1130/g53712.1","url":null,"abstract":"Sedimentary rocks archive the history of Earth’s surface. However, alteration by diagenesis, weathering, deformation, and metamorphism makes interpretating Earth’s earliest environments challenging and ambiguous. We show that detrital zircon grains preserve an unaltered account of transport history, even in billion-year-old sedimentary rocks. We systematically document microscopic features on modern zircon sand grains (“microtextures”) from three continental environments—aeolian, fluvial, and beach foreshore—in modern sediment and Phanerozoic sedimentary rocks of independently known transport history. Our statistical analysis reveals that microtextural assemblages can be used to diagnose transport settings in detrital zircon grains, including recycled grains. Finally, we demonstrate the applicability of zircon microtextural analyses to Precambrian metasedimentary rocks of independently but poorly constrained transport histories. Detrital zircon grains preserve an untapped account of early surface environments, expanding the applicability of sand microtextural analyses to the first 90% of Earth’s history.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"54 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145295228","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}
Jeffery M. Valenza, Alexander C. Whittaker, Vamsi Ganti, Evan Greenberg, Jonah McLeod, Amanda L. Wild
The Silurian radiation of land plants fundamentally altered fluvial stratigraphy and is often associated with a shift in river planform. Recent work challenges the long-held view that pre-vegetation rivers were predominantly braided; however, geologic evidence reconciling the potential for pre-vegetation meandering rivers with the laterally amalgamated, sheet-like sandstones characteristic of pre-Silurian fluvial strata remains limited. Here, we test the hypothesis that pre-Silurian strata instead record evidence for mobile, meandering, and high-sinuosity wandering rivers characterized by rapid floodplain reworking through detailed outcrop scale analysis of the 1.2 Ga Clachtoll Formation (Stoer Group, NW Scotland), one of the best-preserved Mesoproterozoic fluvial systems. Our analysis reveals that bars predominantly accrete orthogonally to dune paleocurrent directions (i.e., lateral accretion), circular variance in dune paleocurrent data is consistent with modern meandering and high-sinuosity wandering river patterns, and channel bodies are isolated within, and in sharp contact with, muddy floodplains. Critically, we find that 87% of fluvial bars are poorly preserved, with no evidence for fully preserved bars, suggesting rapid river mobility. These findings support the interpretation that laterally extensive, poorly preserved sandstones in pre-vegetation strata may represent deposits of mobile meandering and high-sinuosity wandering rivers prone to rapid floodplain reworking.
陆生植物的志留纪辐射从根本上改变了河流地层，并经常与河面的移动有关。最近的研究挑战了长期以来的观点，即未出现植被的河流主要是辫状的；然而，地质证据表明，前志留纪河流地层的横向合并、片状砂岩特征与植被前的曲流河流相协调的可能性仍然有限。在这里，我们通过对保存最完好的中元古代河流系统之一的1.2 Ga Clachtoll组（Stoer Group, NW Scotland）的详细露头尺度分析，验证了一种假设，即前志留纪地层记录了以快速洪漫平原改造为特征的流动、蜿蜒和高弯曲的流浪河流的证据。分析表明，沙洲主要与沙丘古流方向呈垂直方向（即侧向增生），沙丘古流数据的圆形变化与现代曲流和高曲度的流线型相一致，河道体孤立于泥质洪泛平原内，与泥质洪泛平原有明显的接触。重要的是，我们发现87%的河流坝保存得很差，没有证据表明保存完好的河流坝，这表明河流的流动性很快。这些发现支持了这样一种解释，即在前植被地层中横向扩展的、保存较差的砂岩可能代表了易发生快速洪泛平原改造的流动曲流和高曲度徘徊河流的沉积物。
{"title":"Pre-vegetation fluvial sheet sands explained: Bedform and bar architecture evidence for 1.2 Ga rapidly migrating, meandering, and high-sinuosity wandering rivers","authors":"Jeffery M. Valenza, Alexander C. Whittaker, Vamsi Ganti, Evan Greenberg, Jonah McLeod, Amanda L. Wild","doi":"10.1130/g52858.1","DOIUrl":"https://doi.org/10.1130/g52858.1","url":null,"abstract":"The Silurian radiation of land plants fundamentally altered fluvial stratigraphy and is often associated with a shift in river planform. Recent work challenges the long-held view that pre-vegetation rivers were predominantly braided; however, geologic evidence reconciling the potential for pre-vegetation meandering rivers with the laterally amalgamated, sheet-like sandstones characteristic of pre-Silurian fluvial strata remains limited. Here, we test the hypothesis that pre-Silurian strata instead record evidence for mobile, meandering, and high-sinuosity wandering rivers characterized by rapid floodplain reworking through detailed outcrop scale analysis of the 1.2 Ga Clachtoll Formation (Stoer Group, NW Scotland), one of the best-preserved Mesoproterozoic fluvial systems. Our analysis reveals that bars predominantly accrete orthogonally to dune paleocurrent directions (i.e., lateral accretion), circular variance in dune paleocurrent data is consistent with modern meandering and high-sinuosity wandering river patterns, and channel bodies are isolated within, and in sharp contact with, muddy floodplains. Critically, we find that 87% of fluvial bars are poorly preserved, with no evidence for fully preserved bars, suggesting rapid river mobility. These findings support the interpretation that laterally extensive, poorly preserved sandstones in pre-vegetation strata may represent deposits of mobile meandering and high-sinuosity wandering rivers prone to rapid floodplain reworking.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"159 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145261030","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}
Elmar Albers, Svenja Jöns, Axel Gerdes, Andreas Klügel, Christoph Beier, Simone A. Kasemann, Wolfgang Bach
The histograms in Figure 4B and 4C of the original article did not display data in the final bin (Δage = 18 to >20 m.y.) due to a plotting error. In fact, 8.3% of carbonate ages in vesicles and 12.5% in veins fall within this range. The corrected version of Figure 4 is shown in the associated PDF. This omission does not affect the results or conclusions of the study.
{"title":"ERRATUM: Timing of carbon uptake by oceanic crust determined by rock reactivity","authors":"Elmar Albers, Svenja Jöns, Axel Gerdes, Andreas Klügel, Christoph Beier, Simone A. Kasemann, Wolfgang Bach","doi":"10.1130/g52138e.1","DOIUrl":"https://doi.org/10.1130/g52138e.1","url":null,"abstract":"The histograms in Figure 4B and 4C of the original article did not display data in the final bin (Δage = 18 to >20 m.y.) due to a plotting error. In fact, 8.3% of carbonate ages in vesicles and 12.5% in veins fall within this range. The corrected version of Figure 4 is shown in the associated PDF. This omission does not affect the results or conclusions of the study.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"35 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145247563","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}
Dunfeng Xiang, Qigui Mao, David Chew, Zhiyong Zhang, Lin Wu, Nan Wang, Chao Guo, Meng Zhang, Guoxiong Ma, He Yang, Wenjiao Xiao
The West Kunlun (WKL) orogen, a pivotal boundary on the western Tibetan Plateau, records the dynamic interplay between northward underthrusting Indian lithosphere and the Tarim craton. Despite its significance, the exhumation history and mechanisms of plateau growth in this region remain contentious. Here, apatite fission-track (AFT) and (U-Th)/He (AHe) thermochronology data from three bedrock elevation transects across the WKL were used to refine the Miocene exhumation processes in the region. Our results reveal a regionally consistent two-phase acceleration in late Miocene exhumation at ca. 11−10 and ca. 7−6 Ma. Integration with regional thermochronologic, magmatic, and seismic data shows a systematic younging of cooling ages and (ultra)potassic magmatism toward the WKL, alongside increasing exhumation rates. These trends reflect outward plateau expansion driven by progressive indentation of the Indian plate into Asia. This culminated at ca. 11−10 Ma, when the cratonic Indian slab directly impinged the Tarim craton, as evidenced by rapid surface uplift and the formation of ca. 10 Ma and younger (ultra)potassic magmas in the WKL orogen. Our findings highlight the coupling between deep lithospheric processes and surface deformation, providing critical constraints on the timing of the India-Tarim collision and the mechanisms driving plateau growth along the northwestern margin of the Tibetan Plateau.
{"title":"Late Miocene rapid exhumation in the West Kunlun range: Insights into Tibetan Plateau growth and India-Asia lithospheric collision","authors":"Dunfeng Xiang, Qigui Mao, David Chew, Zhiyong Zhang, Lin Wu, Nan Wang, Chao Guo, Meng Zhang, Guoxiong Ma, He Yang, Wenjiao Xiao","doi":"10.1130/g53642.1","DOIUrl":"https://doi.org/10.1130/g53642.1","url":null,"abstract":"The West Kunlun (WKL) orogen, a pivotal boundary on the western Tibetan Plateau, records the dynamic interplay between northward underthrusting Indian lithosphere and the Tarim craton. Despite its significance, the exhumation history and mechanisms of plateau growth in this region remain contentious. Here, apatite fission-track (AFT) and (U-Th)/He (AHe) thermochronology data from three bedrock elevation transects across the WKL were used to refine the Miocene exhumation processes in the region. Our results reveal a regionally consistent two-phase acceleration in late Miocene exhumation at ca. 11−10 and ca. 7−6 Ma. Integration with regional thermochronologic, magmatic, and seismic data shows a systematic younging of cooling ages and (ultra)potassic magmatism toward the WKL, alongside increasing exhumation rates. These trends reflect outward plateau expansion driven by progressive indentation of the Indian plate into Asia. This culminated at ca. 11−10 Ma, when the cratonic Indian slab directly impinged the Tarim craton, as evidenced by rapid surface uplift and the formation of ca. 10 Ma and younger (ultra)potassic magmas in the WKL orogen. Our findings highlight the coupling between deep lithospheric processes and surface deformation, providing critical constraints on the timing of the India-Tarim collision and the mechanisms driving plateau growth along the northwestern margin of the Tibetan Plateau.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"17 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145215822","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}
Anhydrite is considered a rare mineral phase in magmas, with only ∼33 documented occurrences worldwide. However, anhydrite readily decomposes in the near-surface environment, making it difficult to recognize its former presence in rocks collected at or near Earth’s surface. In such samples, only small anhydrite inclusions fully shielded within other minerals can have survived. During a recent field trip to the southwestern USA, we sampled 17 Laramide-age (ca. 40−80 Ma) magma systems, most of which are associated with porphyry copper deposits. A systematic search for anhydrite inclusions preserved within apatite, amphibole, plagioclase, and quartz phenocrysts in ∼100 rock samples by optical microscopy and Raman spectroscopy revealed that each of these 17 magma systems was at least temporarily anhydrite-saturated. Also, most previously identified magmatic anhydrite-bearing intrusions are associated with porphyry copper deposits, and both intrusive and volcanic rocks containing magmatic anhydrite show high Sr/Y ratios. These observations suggest that anhydrite saturation and porphyry copper formation are linked via magma fractionation at high pressure. Compared to average arc magmas, anhydrite-bearing magmas are unusually oxidized and sulfur-rich and seem to also be unusually water-rich. Hence, our preferred interpretation is that magma generation and/or fractionation at high pressure promotes the formation of superhydrous and oxidized magmas, which in turn promotes high sulfur contents and ultimately the precipitation of anhydrite. The high mineralization potential of these magmas does not need to result from their high sulfur content but could be caused by other properties of high-pressure magmas.
{"title":"Widespread anhydrite saturation in Laramide-age arc magmas of the southwestern USA","authors":"Andreas Audétat, Jia Chang, Sean P. Gaynor","doi":"10.1130/g53661.1","DOIUrl":"https://doi.org/10.1130/g53661.1","url":null,"abstract":"Anhydrite is considered a rare mineral phase in magmas, with only ∼33 documented occurrences worldwide. However, anhydrite readily decomposes in the near-surface environment, making it difficult to recognize its former presence in rocks collected at or near Earth’s surface. In such samples, only small anhydrite inclusions fully shielded within other minerals can have survived. During a recent field trip to the southwestern USA, we sampled 17 Laramide-age (ca. 40−80 Ma) magma systems, most of which are associated with porphyry copper deposits. A systematic search for anhydrite inclusions preserved within apatite, amphibole, plagioclase, and quartz phenocrysts in ∼100 rock samples by optical microscopy and Raman spectroscopy revealed that each of these 17 magma systems was at least temporarily anhydrite-saturated. Also, most previously identified magmatic anhydrite-bearing intrusions are associated with porphyry copper deposits, and both intrusive and volcanic rocks containing magmatic anhydrite show high Sr/Y ratios. These observations suggest that anhydrite saturation and porphyry copper formation are linked via magma fractionation at high pressure. Compared to average arc magmas, anhydrite-bearing magmas are unusually oxidized and sulfur-rich and seem to also be unusually water-rich. Hence, our preferred interpretation is that magma generation and/or fractionation at high pressure promotes the formation of superhydrous and oxidized magmas, which in turn promotes high sulfur contents and ultimately the precipitation of anhydrite. The high mineralization potential of these magmas does not need to result from their high sulfur content but could be caused by other properties of high-pressure magmas.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"1 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145215780","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}
Hongwei Ping, Xin Yang, Xiaofeng Liu, Xiaoqiang Li, Honghan Chen, Se Gong, Simon C. George
The Marinoan glaciation was one of the most severe known Snowball Earth climate events, terminating abruptly at ca. 635 Ma with the deposition of globally distributed cap carbonate sediments overlying glacial deposits. This extreme global warming event has been attributed to methane release from the destabilization of gas hydrates, as supported by the abnormally negative δ13C signatures (δ13C = −48‰ to −41‰) of calcite cements that occur in the cap dolostones. However, the hypothesis of gas hydrate destabilization is controversial as the timing of methane release and the methane origin are not clear. Here, we demonstrate that extremely 13C-depleted (δ13C = −51.9‰ to −50.9‰) calcite precipitation occurred much later (618 ± 5.8 Ma) than the termination of Marinoan glaciation in the cap dolostones in South China, and it was associated with thermogenic methane release, as supported by a fluid inclusion gas δ13C1 value (−38.7‰) and the C1/(C2 + C3) ratio measured in the most 13C-depleted calcites. Our findings prove that extremely negative δ13C signatures of calcite cements in cap dolostones are unrelated to clathrate destabilization, thus excluding this mechanism as a cause for the termination of the Marinoan Snowball Earth. This study not only refines our understanding of Ediacaran carbon cycling but also has implications for evaluating hydrocarbon generation in Precambrian sedimentary basins.
{"title":"Thermogenic methane release after Marinoan glaciation induced extremely 13C-depleted calcite precipitation in cap dolostones","authors":"Hongwei Ping, Xin Yang, Xiaofeng Liu, Xiaoqiang Li, Honghan Chen, Se Gong, Simon C. George","doi":"10.1130/g53668.1","DOIUrl":"https://doi.org/10.1130/g53668.1","url":null,"abstract":"The Marinoan glaciation was one of the most severe known Snowball Earth climate events, terminating abruptly at ca. 635 Ma with the deposition of globally distributed cap carbonate sediments overlying glacial deposits. This extreme global warming event has been attributed to methane release from the destabilization of gas hydrates, as supported by the abnormally negative δ13C signatures (δ13C = −48‰ to −41‰) of calcite cements that occur in the cap dolostones. However, the hypothesis of gas hydrate destabilization is controversial as the timing of methane release and the methane origin are not clear. Here, we demonstrate that extremely 13C-depleted (δ13C = −51.9‰ to −50.9‰) calcite precipitation occurred much later (618 ± 5.8 Ma) than the termination of Marinoan glaciation in the cap dolostones in South China, and it was associated with thermogenic methane release, as supported by a fluid inclusion gas δ13C1 value (−38.7‰) and the C1/(C2 + C3) ratio measured in the most 13C-depleted calcites. Our findings prove that extremely negative δ13C signatures of calcite cements in cap dolostones are unrelated to clathrate destabilization, thus excluding this mechanism as a cause for the termination of the Marinoan Snowball Earth. This study not only refines our understanding of Ediacaran carbon cycling but also has implications for evaluating hydrocarbon generation in Precambrian sedimentary basins.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"14 1","pages":""},"PeriodicalIF":5.8,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145209530","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}
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