Mantle plume upwelling and associated topographic doming may affect sedimentation systems over large areas of the Earth’s crust, including drainage basins. An integrated provenance study, including petrography, palaeocurrent data, heavy mineral chemistry, and detrital monazite dating of the Palaeo-Mesozoic Gondwana sandstones in the Mahanadi Basin in eastern India, tracks sediment sources, reconstructs the palaeogeography of eastern Gondwanaland, and records the effects of doming on drainage pattern. The sandstones are mostly arkosic to quartz arenite, sourced from transitional continental to craton interior regions. Garnet chemistry from Permian sandstones suggests a dominant contribution from source rocks metamorphosed under amphibolite to granulite facies conditions. Tourmaline chemistry of the Late Carboniferous to the Late Triassic sandstones links its source primarily to metapelites and metapsammites rocks, while the same indicates predominant Li-poor granitoid sources for the Early Cretaceous sandstones. The spectrum of monazite detrital ages of the Mahanadi sandstones reveals four major clusters: (1) 2385–2249 Ma, (2) 1627–1547 Ma, (3) 1146–662 Ma, and (4) 571–410 Ma. The integration of heavy mineral chemistry, petrography, monazite geochronology, and palaeocurrent data, from the Permo-Carboniferous to the Late Triassic sandstones, establishes sediment sources within the Eastern Ghats Mobile Belt and the Singhbhum Mobile Belt of India, and East Antarctica. In contrast, the southerly palaeocurrent record of the Early Cretaceous deposit indicates sediment supply from the Rengali province of the Eastern Ghats Mobile Belt (EGMB) and the Chhotanagpur Gneissic Complex. Therefore, Early Cretaceous sandstones attest to a change in source rock, primarily controlled by the south-easterly tilting of the basin, linked to the mantle plume-related domal uplift. This study also highlights that before the breakup of Gondwanaland, East Antarctica and EGMB existed as a single landmass.
{"title":"Reversal of drainage patterns related to the Late Cretaceous topographic doming: a case study from eastern Gondwana basins of India","authors":"Sankar Kumar Nahak , N. Prabhakar , Santanu Banerjee , Shreerup Goswami","doi":"10.1016/j.jop.2025.100294","DOIUrl":"10.1016/j.jop.2025.100294","url":null,"abstract":"<div><div>Mantle plume upwelling and associated topographic doming may affect sedimentation systems over large areas of the Earth’s crust, including drainage basins. An integrated provenance study, including petrography, palaeocurrent data, heavy mineral chemistry, and detrital monazite dating of the Palaeo-Mesozoic Gondwana sandstones in the Mahanadi Basin in eastern India, tracks sediment sources, reconstructs the palaeogeography of eastern Gondwanaland, and records the effects of doming on drainage pattern. The sandstones are mostly arkosic to quartz arenite, sourced from transitional continental to craton interior regions. Garnet chemistry from Permian sandstones suggests a dominant contribution from source rocks metamorphosed under amphibolite to granulite facies conditions. Tourmaline chemistry of the Late Carboniferous to the Late Triassic sandstones links its source primarily to metapelites and metapsammites rocks, while the same indicates predominant Li-poor granitoid sources for the Early Cretaceous sandstones. The spectrum of monazite detrital ages of the Mahanadi sandstones reveals four major clusters: (1) 2385–2249 Ma, (2) 1627–1547 Ma, (3) 1146–662 Ma, and (4) 571–410 Ma. The integration of heavy mineral chemistry, petrography, monazite geochronology, and palaeocurrent data, from the Permo-Carboniferous to the Late Triassic sandstones, establishes sediment sources within the Eastern Ghats Mobile Belt and the Singhbhum Mobile Belt of India, and East Antarctica. In contrast, the southerly palaeocurrent record of the Early Cretaceous deposit indicates sediment supply from the Rengali province of the Eastern Ghats Mobile Belt (EGMB) and the Chhotanagpur Gneissic Complex. Therefore, Early Cretaceous sandstones attest to a change in source rock, primarily controlled by the south-easterly tilting of the basin, linked to the mantle plume-related domal uplift. This study also highlights that before the breakup of Gondwanaland, East Antarctica and EGMB existed as a single landmass.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 4","pages":"Article 100294"},"PeriodicalIF":2.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-01DOI: 10.1016/j.jop.2025.100289
Stephen Kershaw , Qi-Jian Li
<div><div>Hypercalcified sponges are poriferans with a calcareous skeleton secreted on and in the soft tissue. Living examples, and fossils of some such sponges in Mesozoic and Cenozoic strata, contain sponge spicules and can be classified within modern poriferan groups of the Classes Demospongiae and Calcarea, which are otherwise almost entirely soft-bodied. However, other fossil forms, largely Palaeozoic archaeocyaths, stromatoporoids and chaetetids, lack spicules, so their classification relies on the calcareous skeleton alone. Because of these discrepancies, although the hypercalcified skeleton is useful for low-level taxonomy in fossils, it has no proven phyletic value, so the systematic position of non-spiculate forms is problematic. Thus the hypercalcified skeleton has for many years been considered a grade of organisation of the skeleton, and the terms archaeocyath-grade, stromatoporoid-grade, chaetetid-grade, sphinctozoan-grade and inozoan-grade are applicable. Nevertheless, archaeocyaths have also been separated as a class, by sponge researchers, creating a quandary about their taxonomic status. Two older classification terms are redundant: sclerosponges (previously a class of all hypercalcified sponges) and pharetronids (previously a subgroup now divided into sphinctozoans and inozoans). Pharetronids are polyphyletic within the Demospongiae and Calcarea.</div><div>Hypercalcified sponges’ history began with archaeocyaths (early-mid Cambrian). Then, prominence of stromatoporoid-grade in the mid-Palaeozoic, and chaetetid-grade in the Carboniferous, was followed by a sparse record in both groups for much of the Permian while sphinctozoan- and inozoan-grades expanded. The Mesozoic has a good record of sphinctozoans, inozoans, stromatoporoids and chaetetids up to the end-Cretaceous. Cenozoic forms are uncommon but 19 genera of modern-day demosponges and calcarean sponges encompass all five grades, versus the total modern sponge diversity of 680 genera. Hypercalcification is diverse in modern sponges, involving aragonite, high-Mg and low-Mg calcite; ancient groups reflect this range in their variation of preservation (including widespread diagenetic alteration) that makes understanding of hypercalcification mechanisms problematic.</div><div>Presence of hypercalcified sponges from Early Cambrian to modern times, with short breaks associated with extinction events, demonstrates that hypercalcification was an iterative evolutionary feature. For example, the stromatoporoid-grade appeared in Early to Mid-Ordovician and continued through geological history to modern representatives, albeit with taxa turnover through time. Stromatoporoids are traditionally viewed as becoming extinct at the end-Devonian Hangenberg event, but because they form a grade, rather than a proven phyletic group, discussion of the extinction of stromatoporoids as a group has little meaning; it is more appropriate to consider that certain sponge taxa, possessing stromatoporoid
高钙化海绵是一种在软组织上分泌钙质骨架的多孔体。在中生代和新生代地层中发现的活生生的海绵标本和一些海绵化石中含有海绵针状体，它们可以被归入现代多孔动物群Demospongiae和calcalarea，除此之外它们几乎都是软体动物。然而，其他化石形式，主要是古生代古石、层孔虫和毛纲，缺乏针状体，因此它们的分类仅依赖于钙质骨架。由于这些差异，尽管高钙化骨骼在化石的低级分类中是有用的，但它没有被证明的种系价值，因此非针状形态的系统位置是有问题的。因此，多年来高钙化骨骼一直被认为是骨骼组织的一个等级，而术语“古囊体级”、“叠层虫级”、“毛纲级”、“鞘虫级”和“无尾虫级”都是适用的。然而，海绵研究人员也将古土生动物划分为一个类别，这使它们的分类地位陷入了困境。两个较早的分类术语是多余的：硬海绵动物（以前是所有高钙化海绵的一类）和吸足类动物（以前是一个亚群，现在分为括约肌动物和无尾动物）。在Demospongiae和calcalarea中，phareconids是多系的。高钙化海绵的历史始于古石（早-中寒武纪）。然后，叠层虫级在中古生代突出，毛纲级在石炭纪突出，在二叠纪的大部分时间里，这两个组的记录都很稀少，而括面虫和inozoa级则扩大了。中生代一直到白垩纪末，都有很好的鞘虫、inozoa、层孔虫和毛纲记录。新生代的形态并不常见，但现代脱海绵和钙质海绵的19属涵盖了所有五个等级，而现代海绵的多样性为680属。现代海绵的高钙化是多种多样的，包括文石、高镁和低镁方解石；古代群体在其保存变化（包括广泛的成岩蚀变）中反映了这一范围，这使得对高钙化机制的理解存在问题。早寒武纪至现代高钙化海绵的存在，以及与灭绝事件相关的短暂间歇，表明高钙化是一个迭代的进化特征。例如，叠层虫级出现在早奥陶世至中奥陶世，并通过地质历史延续到现代代表，尽管分类群随着时间的推移而更替。叠孔虫传统上被认为是在泥盆纪末的Hangenberg事件中灭绝的，但由于它们形成了一个等级，而不是一个已证实的种系群，因此讨论叠孔虫作为一个群体的灭绝几乎没有意义；更恰当的说法是，某些具有层孔类骨骼的海绵分类群已经灭绝了。下石炭世地层中罕见的层虫级分类群支持了这一观点。尽管它们的多系性在中生代和新生代中得到了认可，但2015年的《高钙化海绵专著》（Treatise on hyper钙化海绵）将层孔虫和古石虫视为不同的类群。现代高钙化海绵是碰巧发生高钙化的海绵类群。因此，高钙化海绵化石最好被认为是在Demospongiae类和Calcarea类中复杂多样的骨骼形态空间中的高钙化系统，以及Porifera门的进化史，以帮助理解它们的时间变化。
{"title":"Fossil hypercalcified sponges; types, relationships and geological history","authors":"Stephen Kershaw , Qi-Jian Li","doi":"10.1016/j.jop.2025.100289","DOIUrl":"10.1016/j.jop.2025.100289","url":null,"abstract":"<div><div>Hypercalcified sponges are poriferans with a calcareous skeleton secreted on and in the soft tissue. Living examples, and fossils of some such sponges in Mesozoic and Cenozoic strata, contain sponge spicules and can be classified within modern poriferan groups of the Classes Demospongiae and Calcarea, which are otherwise almost entirely soft-bodied. However, other fossil forms, largely Palaeozoic archaeocyaths, stromatoporoids and chaetetids, lack spicules, so their classification relies on the calcareous skeleton alone. Because of these discrepancies, although the hypercalcified skeleton is useful for low-level taxonomy in fossils, it has no proven phyletic value, so the systematic position of non-spiculate forms is problematic. Thus the hypercalcified skeleton has for many years been considered a grade of organisation of the skeleton, and the terms archaeocyath-grade, stromatoporoid-grade, chaetetid-grade, sphinctozoan-grade and inozoan-grade are applicable. Nevertheless, archaeocyaths have also been separated as a class, by sponge researchers, creating a quandary about their taxonomic status. Two older classification terms are redundant: sclerosponges (previously a class of all hypercalcified sponges) and pharetronids (previously a subgroup now divided into sphinctozoans and inozoans). Pharetronids are polyphyletic within the Demospongiae and Calcarea.</div><div>Hypercalcified sponges’ history began with archaeocyaths (early-mid Cambrian). Then, prominence of stromatoporoid-grade in the mid-Palaeozoic, and chaetetid-grade in the Carboniferous, was followed by a sparse record in both groups for much of the Permian while sphinctozoan- and inozoan-grades expanded. The Mesozoic has a good record of sphinctozoans, inozoans, stromatoporoids and chaetetids up to the end-Cretaceous. Cenozoic forms are uncommon but 19 genera of modern-day demosponges and calcarean sponges encompass all five grades, versus the total modern sponge diversity of 680 genera. Hypercalcification is diverse in modern sponges, involving aragonite, high-Mg and low-Mg calcite; ancient groups reflect this range in their variation of preservation (including widespread diagenetic alteration) that makes understanding of hypercalcification mechanisms problematic.</div><div>Presence of hypercalcified sponges from Early Cambrian to modern times, with short breaks associated with extinction events, demonstrates that hypercalcification was an iterative evolutionary feature. For example, the stromatoporoid-grade appeared in Early to Mid-Ordovician and continued through geological history to modern representatives, albeit with taxa turnover through time. Stromatoporoids are traditionally viewed as becoming extinct at the end-Devonian Hangenberg event, but because they form a grade, rather than a proven phyletic group, discussion of the extinction of stromatoporoids as a group has little meaning; it is more appropriate to consider that certain sponge taxa, possessing stromatoporoid","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 4","pages":"Article 100289"},"PeriodicalIF":2.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145323833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-01DOI: 10.1016/j.jop.2025.100293
Chao Li , Zhi-Yuan He , Sheng-Li Wang , Yan Chen , Yi-Fan Shi , Guo-Hui Chen , Shao-Wen Liu , Yun-Jian Li , Fei Xue , Wen-Bo Rao
The Cenozoic uplift of the Central Asia Tian Shan Mountains has driven significant subsidence in the foreland basins along its northern and southern flanks, leading to the extensive deposition of the Late Cenozoic alluvial-gravel deposits at its piedmonts known as the Xiyu Conglomerates. At the base of these conglomerates, localized gravel deposition replaces sandstones vertically over tens of meters with a sharp increase in median grain size (D50) by c. 100-fold. However, the origin of the transition remains a subject of controversy, with multiple potential factors intricately linked to regional tectonics and climatic variations. To address this question, we investigated the grain size variations of modern riverbed sediments along six rivers and the Xiyu Conglomerates in two sections within the northern foreland area of Tian Shan Mountains. We observed a rapid gravel–sand transition (GST) along the present-day rivers, 20–50 km downstream from the outlet, as well as a sharp conglomerate–sandstone transition at the base of the Xiyu Conglomerates, both of which exhibit similar fining rates. Furthermore, a provenance investigation of the Jingou River basin, using heavy mineral assemblages and detrital zircon U–Pb ages, indicates consistent sources for both the Xiyu Conglomerates and modern riverbed sediments. The combined results suggest that the striking grain size changes observed in both the Xiyu Conglomerates and along these modern rivers from similar internal hydraulic processes within the piedmont rivers, specifically size-selective sorting controlled by the bimodal grain size distribution of sediments. This implies that the emergence of sharp grain size transitions in the vertical successions was a result of the continuous northward progradation of the GST in the basin, driven by the long-term northward thrusting of the Tian Shan Mountains, independent of sharp and specific changes in climatic or tectonic forcing events. The average northward migration rate of the GSTs is calculated to be 3.9 ± 0.2 mm/yr since c. 7.5 Ma along 85°30′E, and 7.6 ± 2.1 mm/yr since c. 2.1 Ma along 86°30′E. These rates closely reflect the long-term crustal shortening rates across the northern Tian Shan Mountains, and its increase may denote an acceleration of the shortening post-Miocene.
{"title":"Linking rapid grain size coarsening in the Neogene Xiyu Conglomerates to gravel–sand transitions in modern northern Tian Shan rivers: Evidence of shared origins from field and provenance investigations","authors":"Chao Li , Zhi-Yuan He , Sheng-Li Wang , Yan Chen , Yi-Fan Shi , Guo-Hui Chen , Shao-Wen Liu , Yun-Jian Li , Fei Xue , Wen-Bo Rao","doi":"10.1016/j.jop.2025.100293","DOIUrl":"10.1016/j.jop.2025.100293","url":null,"abstract":"<div><div>The Cenozoic uplift of the Central Asia Tian Shan Mountains has driven significant subsidence in the foreland basins along its northern and southern flanks, leading to the extensive deposition of the Late Cenozoic alluvial-gravel deposits at its piedmonts known as the Xiyu Conglomerates. At the base of these conglomerates, localized gravel deposition replaces sandstones vertically over tens of meters with a sharp increase in median grain size (D50) by c. 100-fold. However, the origin of the transition remains a subject of controversy, with multiple potential factors intricately linked to regional tectonics and climatic variations. To address this question, we investigated the grain size variations of modern riverbed sediments along six rivers and the Xiyu Conglomerates in two sections within the northern foreland area of Tian Shan Mountains. We observed a rapid gravel–sand transition (GST) along the present-day rivers, 20–50 km downstream from the outlet, as well as a sharp conglomerate–sandstone transition at the base of the Xiyu Conglomerates, both of which exhibit similar fining rates. Furthermore, a provenance investigation of the Jingou River basin, using heavy mineral assemblages and detrital zircon U–Pb ages, indicates consistent sources for both the Xiyu Conglomerates and modern riverbed sediments. The combined results suggest that the striking grain size changes observed in both the Xiyu Conglomerates and along these modern rivers from similar internal hydraulic processes within the piedmont rivers, specifically size-selective sorting controlled by the bimodal grain size distribution of sediments. This implies that the emergence of sharp grain size transitions in the vertical successions was a result of the continuous northward progradation of the GST in the basin, driven by the long-term northward thrusting of the Tian Shan Mountains, independent of sharp and specific changes in climatic or tectonic forcing events. The average northward migration rate of the GSTs is calculated to be 3.9 ± 0.2 mm/yr since c. 7.5 Ma along 85°30′E, and 7.6 ± 2.1 mm/yr since c. 2.1 Ma along 86°30′E. These rates closely reflect the long-term crustal shortening rates across the northern Tian Shan Mountains, and its increase may denote an acceleration of the shortening post-Miocene.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 4","pages":"Article 100293"},"PeriodicalIF":2.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-30DOI: 10.1016/j.jop.2025.100297
Jun Ma , Zheng-Fang Li , Ben-Gang Zhou , Ming-Ming Wang , Mahdi Motagh
The Xianshuihe Fault Zone (XSHF) frequently experiences strong earthquakes owing to its high slip rate; particularly, the Kangding segment within the XSHF is structurally complex. To conduct an accurate regional seismic hazard analysis of XSHF, it is necessary to understand the slip rates of the branch faults of the Kangding segment. In this study, we aimed to determine the slip rates of the Yalahe Fault (YLHF) and the northwestern segment of the Zheduotang Fault (ZDTF), which are both parts of the Kangding segment. We employed tectonic geomorphology, topographic data, terrestrial laser scanning, precise offset measurements using LaDiCaoz_v2 software, and 10Be cosmogenic nuclide dating techniques. Our analysis showed slip rates of 3.5 ± 0.3 mm·yr−1 and 2.3 ± 0.2 mm·yr−1 since 12.7 ka and 7.8 ka for the YLHF, implying a decreasing slip rate trend post the Holocene period. Furthermore, we obtained slip rates of 1.9 ± 0.3 mm·yr−1 since 42.7 ka and 1.8 ± 0.2 mm·yr−1 since 15.7 ka for the northwest segment of the ZDTF. Notably, these slip rates are significantly lower than those observed for the southeastern ZDTF. Furthermore, in the late Quaternary, the combined slip rate for the XSHF reached a maximum of 9.9–15.5 mm·yr−1. We also observed that the Anninghe Fault inherited 48.2 % of slip rate from XSHF. These findings provide a comprehensive overview of slip rate partitioning among branch faults in the Kangding segment, offering novel insights into the seismic behavior of the XSHF and improving regional seismic hazard assessment.
{"title":"Spatial slip rate partitioning along the Xianshuihe Fault Zone, eastern Tibetan Plateau","authors":"Jun Ma , Zheng-Fang Li , Ben-Gang Zhou , Ming-Ming Wang , Mahdi Motagh","doi":"10.1016/j.jop.2025.100297","DOIUrl":"10.1016/j.jop.2025.100297","url":null,"abstract":"<div><div>The Xianshuihe Fault Zone (XSHF) frequently experiences strong earthquakes owing to its high slip rate; particularly, the Kangding segment within the XSHF is structurally complex. To conduct an accurate regional seismic hazard analysis of XSHF, it is necessary to understand the slip rates of the branch faults of the Kangding segment. In this study, we aimed to determine the slip rates of the Yalahe Fault (YLHF) and the northwestern segment of the Zheduotang Fault (ZDTF), which are both parts of the Kangding segment. We employed tectonic geomorphology, topographic data, terrestrial laser scanning, precise offset measurements using LaDiCaoz_v2 software, and <sup>10</sup>Be cosmogenic nuclide dating techniques. Our analysis showed slip rates of 3.5 ± 0.3 mm·yr<sup>−1</sup> and 2.3 ± 0.2 mm·yr<sup>−1</sup> since 12.7 ka and 7.8 ka for the YLHF, implying a decreasing slip rate trend post the Holocene period. Furthermore, we obtained slip rates of 1.9 ± 0.3 mm·yr<sup>−1</sup> since 42.7 ka and 1.8 ± 0.2 mm·yr<sup>−1</sup> since 15.7 ka for the northwest segment of the ZDTF. Notably, these slip rates are significantly lower than those observed for the southeastern ZDTF. Furthermore, in the late Quaternary, the combined slip rate for the XSHF reached a maximum of 9.9–15.5 mm·yr<sup>−1</sup>. We also observed that the Anninghe Fault inherited 48.2 % of slip rate from XSHF. These findings provide a comprehensive overview of slip rate partitioning among branch faults in the Kangding segment, offering novel insights into the seismic behavior of the XSHF and improving regional seismic hazard assessment.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 1","pages":"Article 100297"},"PeriodicalIF":2.0,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-26DOI: 10.1016/j.jop.2025.100296
Qing Bian , Ji-Biao Zhang , Fan Feng , Yang Li , Chen-Jun Huang , Tie-Yi Wang , Kang-Kang Guo
The Middle-Lower Cambrian Wusongge'er Formation in the Tarim Basin hosts extensive evaporite deposits, yet the formative processes of these evaporites under equatorial arid climates and their tectono-sedimentary implications remain poorly constrained. Previous studies, limited to low-resolution seismic data and outcrops in the northwestern margin, failed to resolve depositional variations in the central basin. This study aims to decipher the genetic mechanisms of evaporite precipitation and reconstruct the prototype basin's tectono-sedimentary evolution by integrating high-quality 3D seismic data (2023), geophysical forward modeling, and palaeogeographic reconstructions. Integrated analyses revealed a distinct zoned “west halite-east gypsum/dolomite” pattern driven by paleosalinity gradients in a semi-closed lagoon system, alongside an elongated reef body in the middle ramp and thrombolite buildups in the inner ramp. Evaporite distribution was dominantly controlled by equatorial aridity (climate) and fault-induced differential subsidence (tectonics), with the latter creating thickness variations exceeding 300 m. This study establishes a genetic model of evaporite sedimentation under the Cambrian greenhouse conditions, providing analogues for coeval evaporite systems in Gondwana. The restored prototype basin configuration reveals salt-driven sediment partitioning processes, offering new insights into the tectono-sedimentary evolution of intracratonic basins. While seismic interpretations face limitations in deep zones with scarce drilling data, this framework guides future ultra-deep exploration targeting salt-tectonized traps below 8000 m depth.
{"title":"Sedimentary distribution of evaporites in Wusongge'er Formation in central Tarim Basin and reconstruction of prototype basin","authors":"Qing Bian , Ji-Biao Zhang , Fan Feng , Yang Li , Chen-Jun Huang , Tie-Yi Wang , Kang-Kang Guo","doi":"10.1016/j.jop.2025.100296","DOIUrl":"10.1016/j.jop.2025.100296","url":null,"abstract":"<div><div>The Middle-Lower Cambrian Wusongge'er Formation in the Tarim Basin hosts extensive evaporite deposits, yet the formative processes of these evaporites under equatorial arid climates and their tectono-sedimentary implications remain poorly constrained. Previous studies, limited to low-resolution seismic data and outcrops in the northwestern margin, failed to resolve depositional variations in the central basin. This study aims to decipher the genetic mechanisms of evaporite precipitation and reconstruct the prototype basin's tectono-sedimentary evolution by integrating high-quality 3D seismic data (2023), geophysical forward modeling, and palaeogeographic reconstructions. Integrated analyses revealed a distinct zoned “west halite-east gypsum/dolomite” pattern driven by paleosalinity gradients in a semi-closed lagoon system, alongside an elongated reef body in the middle ramp and thrombolite buildups in the inner ramp. Evaporite distribution was dominantly controlled by equatorial aridity (climate) and fault-induced differential subsidence (tectonics), with the latter creating thickness variations exceeding 300 m. This study establishes a genetic model of evaporite sedimentation under the Cambrian greenhouse conditions, providing analogues for coeval evaporite systems in Gondwana. The restored prototype basin configuration reveals salt-driven sediment partitioning processes, offering new insights into the tectono-sedimentary evolution of intracratonic basins. While seismic interpretations face limitations in deep zones with scarce drilling data, this framework guides future ultra-deep exploration targeting salt-tectonized traps below 8000 m depth.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 1","pages":"Article 100296"},"PeriodicalIF":2.0,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-26DOI: 10.1016/j.jop.2025.100295
Long Sun , Sheng-He Wu , Da-Li Yue , Si-Chong Jiang , Wei Du , Li-Jun Yang , Zhen-Hua Xu , Ke Zhang
The Early Cretaceous greenhouse climate was interrupted by multiple intermittent cold snaps such as the Valanginian cold snap and late Aptian climate cooling events, but there is currently a lack of terrestrial palaeoweathering and palaeoclimate records for the early Aptian climate cooling event. The relationship between the regional climate of terrestrial lake basins and the global climate during the early Aptian is still unclear. The Luanping Basin, which is located in the northeastern North China Craton (NCC) and contains Lower Cretaceous sediments with a maximum thickness of ∼3200 m, is an ideal place for analysing the terrestrial weathering and climate. Sixteen mudstone samples were collected from the Lower Cretaceous upper Xiguayuan Formation in the Luanping Basin. The mineral compositions and major, trace and rare earth element contents of the mudstone samples were quantitatively determined via X-ray diffraction (XRD), X-ray fluorescence (XRF), and inductively coupled plasma‒mass spectrometry (ICP‒MS), respectively. Elemental geochemical analyses were carried out to determine palaeoweathering intensity, palaeoclimatic conditions, and their relationships with the global climate. The variation trends in multiple chemical weathering indices are reconstructed after the interference of nonweathering factors is eliminated, reflecting that the source area has experienced mainly weak to moderate weathering. After evaluating the influences of carbonate-sourced elements, we infer that the regional palaeoclimate is arid and cold on the basis of the Sr/Cu ratio, Rb/Sr ratio, C-value, land surface temperature (LST), and mean annual temperature (MAT). All chemical weathering indices and palaeoclimate proxies exhibit similar trends. Moreover, the cooling of palaeotemperatures could have been a response to the early Aptian global cold snap. The regional climate of the Luanping Basin is controlled mainly by global climate change, which provides terrestrial weathering and climate records for the early Aptian global cooling event.
{"title":"Palaeoweathering and palaeoclimate of the Lower Cretaceous upper Xiguayuan Formation in the Luanping Basin, North China: Implications for early Aptian global cooling","authors":"Long Sun , Sheng-He Wu , Da-Li Yue , Si-Chong Jiang , Wei Du , Li-Jun Yang , Zhen-Hua Xu , Ke Zhang","doi":"10.1016/j.jop.2025.100295","DOIUrl":"10.1016/j.jop.2025.100295","url":null,"abstract":"<div><div>The Early Cretaceous greenhouse climate was interrupted by multiple intermittent cold snaps such as the Valanginian cold snap and late Aptian climate cooling events, but there is currently a lack of terrestrial palaeoweathering and palaeoclimate records for the early Aptian climate cooling event. The relationship between the regional climate of terrestrial lake basins and the global climate during the early Aptian is still unclear. The Luanping Basin, which is located in the northeastern North China Craton (NCC) and contains Lower Cretaceous sediments with a maximum thickness of ∼3200 m, is an ideal place for analysing the terrestrial weathering and climate. Sixteen mudstone samples were collected from the Lower Cretaceous upper Xiguayuan Formation in the Luanping Basin. The mineral compositions and major, trace and rare earth element contents of the mudstone samples were quantitatively determined via X-ray diffraction (XRD), X-ray fluorescence (XRF), and inductively coupled plasma‒mass spectrometry (ICP‒MS), respectively. Elemental geochemical analyses were carried out to determine palaeoweathering intensity, palaeoclimatic conditions, and their relationships with the global climate. The variation trends in multiple chemical weathering indices are reconstructed after the interference of nonweathering factors is eliminated, reflecting that the source area has experienced mainly weak to moderate weathering. After evaluating the influences of carbonate-sourced elements, we infer that the regional palaeoclimate is arid and cold on the basis of the Sr/Cu ratio, Rb/Sr ratio, C-value, land surface temperature (LST), and mean annual temperature (MAT). All chemical weathering indices and palaeoclimate proxies exhibit similar trends. Moreover, the cooling of palaeotemperatures could have been a response to the early Aptian global cold snap. The regional climate of the Luanping Basin is controlled mainly by global climate change, which provides terrestrial weathering and climate records for the early Aptian global cooling event.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 1","pages":"Article 100295"},"PeriodicalIF":2.0,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-17DOI: 10.1016/j.jop.2025.100292
Ning Tian , Zi-Hui Sheng , Fang-Yu Li , Ning Lu , Meng-Yu Chen , Wen-Tao Liu
China possesses an abundant fossil record of Mesozoic ferns, predominantly preserved as leaf compressions or impressions. In contrast, permineralized fern fossils revealing anatomical details are comparatively rare. Recently, a novel permineralized flora was discovered from the Middle Jurassic Xinmin Formation in Horqin Right Wing Middle Banner, Northeast China, yielding diverse permineralized plant remains. Here, we report a new permineralized fern rhizome genus Shaolinopteris gen. nov. from this flora. The new genus is anatomically characterized by a solenostele with exarch protoxylem, a homogeneous pith, a two-layered rhizome cortex, and “Dennstaedtia-type” adventitious roots featuring diarch protoxylems. Notably, the rhizome inner cortex comprises aerenchymatous columns. Anatomical analysis of Shaolinopteris indicates probable phylogenetic affiliation with the extant fern family Dennstaedtiaceae. Furthermore, a comprehensive revision of the fossil diversity and palaeogeographical distribution of Mesozoic solenostelic fern rhizomes is presented. This new specimen constitutes the first documented occurrence of Mesozoic solenostelic ferns in continental East Asia, providing critical evidence for reconstructing the palaeophytogeography of these taxa.
中国拥有丰富的中生代蕨类化石记录，主要保存为叶片压缩或印痕。相比之下，揭示解剖细节的过矿化蕨类化石相对较少。最近，在东北科尔沁右中旗中侏罗统新民组中发现了一种新的过矿化植物区系，发现了多种过矿化植物遗迹。本文报道了该植物区系中一个新的过矿化蕨类根茎属Shaolinopteris gen. 11。新属的解剖学特征是：具有直立原木质部的螺线索，同质髓，双层根茎皮质，以及具有直立原木质部的“Dennstaedtia-type”不定根。值得注意的是，根茎内皮层由通气柱组成。解剖分析表明其可能与现存蕨科蕨科有亲缘关系。此外，还对中生代扶桑蕨类根茎的化石多样性和古地理分布进行了全面的修正。这一新标本构成了东亚大陆中生代螺线形蕨类植物的首次记录，为重建这些分类群的古植物地理提供了重要证据。
{"title":"Shaolinopteris gen. nov., a new fern rhizome genus with solenostele from the Jurassic of Northeast China and its palaeogeographic and taxonomic implications","authors":"Ning Tian , Zi-Hui Sheng , Fang-Yu Li , Ning Lu , Meng-Yu Chen , Wen-Tao Liu","doi":"10.1016/j.jop.2025.100292","DOIUrl":"10.1016/j.jop.2025.100292","url":null,"abstract":"<div><div>China possesses an abundant fossil record of Mesozoic ferns, predominantly preserved as leaf compressions or impressions. In contrast, permineralized fern fossils revealing anatomical details are comparatively rare. Recently, a novel permineralized flora was discovered from the Middle Jurassic Xinmin Formation in Horqin Right Wing Middle Banner, Northeast China, yielding diverse permineralized plant remains. Here, we report a new permineralized fern rhizome genus <em>Shaolinopteris</em> gen. nov. from this flora. The new genus is anatomically characterized by a solenostele with exarch protoxylem, a homogeneous pith, a two-layered rhizome cortex, and “<em>Dennstaedtia</em>-type” adventitious roots featuring diarch protoxylems. Notably, the rhizome inner cortex comprises aerenchymatous columns. Anatomical analysis of <em>Shaolinopteris</em> indicates probable phylogenetic affiliation with the extant fern family Dennstaedtiaceae. Furthermore, a comprehensive revision of the fossil diversity and palaeogeographical distribution of Mesozoic solenostelic fern rhizomes is presented. This new specimen constitutes the first documented occurrence of Mesozoic solenostelic ferns in continental East Asia, providing critical evidence for reconstructing the palaeophytogeography of these taxa.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 1","pages":"Article 100292"},"PeriodicalIF":2.0,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145223480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-01DOI: 10.1016/j.jop.2025.100290
Wei-Qing Liu , Lu-Qi Chen , Hua-Ying Song , Yu Qiao , Su-Ping Li , Wei Wu , Chang-Song Lin , Jian-Xin Yao
The organic-rich black oil shales of the Upper Triassic Tanzhuang Formation represent important source rocks within the southern North China Block. However, the mechanism of organic matter enrichment remains unclear. Additionally, the climate evolution and driving factors of the Late Triassic in the southern North China Block are still unknown. This study explores the paleoclimate, paleohydrology, paleoenvironment, and organic matter accumulation mechanism of the section containing the Tanzhuang Formation in the Jiyuan area, utilizing its geochemical characteristics as a basis for analysis. The oil shales in the Tanzhuang Formation can be categorized into two types: organic-rich shales (with total organic carbon (TOC) contents varying between 1.61 % and 4.17 %) and organic-lean shales (with TOC contents varying between 0.29 % and 1.44 %). The paleoclimatic indices, the chemical alteration index (CIA) and the C value, suggest that the organic-lean shales were deposited under warm and semihumid paleoclimatic conditions, whereas the organic-rich black shales formed under warm and humid climate conditions. The positive correlation between the Hg/Al ratios and C values suggests that volcanic activity was the cause of paleoclimatic changes, which may have been associated with global climatic events that occurred during the Late Triassic Carnian period. The oxidation–reduction indices, V, U, and Mo contents and the Mo–U correlation diagram indicate that dysoxic conditions prevailed in the Jiyuan Basin during the deposition of the oil shales in the Tanzhuang Formation. The primary productivity indices (e.g., CuEF and ZnEF) suggest that higher primary productivity was observed during the deposition of the organic-rich shales. The positive correlations between the TOC contents and the CuEF and C values indicate that the enrichment of organic matter in the oil shales of the Tanzhuang Formation was influenced primarily by primary productivity and a warm and humid climate. The sedimentary model indicates that the elevated primary productivity may have originated from a warm and humid climate coupled with intense weathering caused by volcanic activity during the Late Triassic period, which formed a productivity model characterized by the accumulation of organic matter in the oil shales of the Tanzhuang Formation.
{"title":"Geochemical characteristics of the Upper Triassic Tanzhuang Formation in the Jiyuan sag, southern North China Block: Implications for the depositional environment and organic matter enrichment","authors":"Wei-Qing Liu , Lu-Qi Chen , Hua-Ying Song , Yu Qiao , Su-Ping Li , Wei Wu , Chang-Song Lin , Jian-Xin Yao","doi":"10.1016/j.jop.2025.100290","DOIUrl":"10.1016/j.jop.2025.100290","url":null,"abstract":"<div><div>The organic-rich black oil shales of the Upper Triassic Tanzhuang Formation represent important source rocks within the southern North China Block. However, the mechanism of organic matter enrichment remains unclear. Additionally, the climate evolution and driving factors of the Late Triassic in the southern North China Block are still unknown. This study explores the paleoclimate, paleohydrology, paleoenvironment, and organic matter accumulation mechanism of the section containing the Tanzhuang Formation in the Jiyuan area, utilizing its geochemical characteristics as a basis for analysis. The oil shales in the Tanzhuang Formation can be categorized into two types: organic-rich shales (with total organic carbon (TOC) contents varying between 1.61 % and 4.17 %) and organic-lean shales (with TOC contents varying between 0.29 % and 1.44 %). The paleoclimatic indices, the chemical alteration index (CIA) and the C value, suggest that the organic-lean shales were deposited under warm and semihumid paleoclimatic conditions, whereas the organic-rich black shales formed under warm and humid climate conditions. The positive correlation between the Hg/Al ratios and C values suggests that volcanic activity was the cause of paleoclimatic changes, which may have been associated with global climatic events that occurred during the Late Triassic Carnian period. The oxidation–reduction indices, V, U, and Mo contents and the Mo–U correlation diagram indicate that dysoxic conditions prevailed in the Jiyuan Basin during the deposition of the oil shales in the Tanzhuang Formation. The primary productivity indices (e.g., Cu<sub>EF</sub> and Zn<sub>EF</sub>) suggest that higher primary productivity was observed during the deposition of the organic-rich shales. The positive correlations between the TOC contents and the Cu<sub>EF</sub> and C values indicate that the enrichment of organic matter in the oil shales of the Tanzhuang Formation was influenced primarily by primary productivity and a warm and humid climate. The sedimentary model indicates that the elevated primary productivity may have originated from a warm and humid climate coupled with intense weathering caused by volcanic activity during the Late Triassic period, which formed a productivity model characterized by the accumulation of organic matter in the oil shales of the Tanzhuang Formation.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 4","pages":"Article 100290"},"PeriodicalIF":2.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145157624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-19DOI: 10.1016/j.jop.2025.100287
Xue-Lian Guo , Gregory J. Retallack , Shuang Dai
Paleosols in the Late Devonian (Famennian) Shaliushui and Qianheishan formations near Pingchuan, in northeast Gansu, China, are characterized petrographically and chemically to reconstruct paleoenvironments early in the evolution of forests on Earth. The Devonian paleosols, analogous to Neogene paleosols in the Lesser Himalaya of India, formed within the outwash plain of an extremely high (5–8 km elevation) mountain range on the North Qilian Block resulting from continent–continent collision in North China. Such high paleoaltitude is evidenced by Devonian paleosols exhibiting unusually thick horizons of subsurface calcareous nodules, as evidence of inferred mean annual precipitation range of 107 ± 22 mm. These conditions are comparable to those observed in paleosols from India, where monsoonal seasonality is driven by extreme elevation differences. Depth to Bk (calcic horizon) corrected for burial compaction of the paleosols reveals semiarid mean annual precipitation (MAP) of 361 ± 147 mm, with some subhumid outliers of 563 ± 147 mm. Chemical composition of the paleosols is evidence of subhumid (MAP 572 ± 182 mm, but up to 936 ± 182 mm) and temperate climates (MAT 12.5 ± 4.4 °C, but up to 14.9 ± 4.4 °C). Such cool temperatures at low paleolatitude (5-20°) are additional evidence of high elevation of at least 1 km. The vegetation consisted of Devonian pteridophytic progymnosperms, evidenced by rare foliar spurs and common woody root traces.
{"title":"Devonian-Carboniferous paleosols and tectonics of northwest China","authors":"Xue-Lian Guo , Gregory J. Retallack , Shuang Dai","doi":"10.1016/j.jop.2025.100287","DOIUrl":"10.1016/j.jop.2025.100287","url":null,"abstract":"<div><div>Paleosols in the Late Devonian (Famennian) Shaliushui and Qianheishan formations near Pingchuan, in northeast Gansu, China, are characterized petrographically and chemically to reconstruct paleoenvironments early in the evolution of forests on Earth. The Devonian paleosols, analogous to Neogene paleosols in the Lesser Himalaya of India, formed within the outwash plain of an extremely high (5–8 km elevation) mountain range on the North Qilian Block resulting from continent–continent collision in North China. Such high paleoaltitude is evidenced by Devonian paleosols exhibiting unusually thick horizons of subsurface calcareous nodules, as evidence of inferred mean annual precipitation range of 107 ± 22 mm. These conditions are comparable to those observed in paleosols from India, where monsoonal seasonality is driven by extreme elevation differences. Depth to Bk (calcic horizon) corrected for burial compaction of the paleosols reveals semiarid mean annual precipitation (MAP) of 361 ± 147 mm, with some subhumid outliers of 563 ± 147 mm. Chemical composition of the paleosols is evidence of subhumid (MAP 572 ± 182 mm, but up to 936 ± 182 mm) and temperate climates (MAT 12.5 ± 4.4 °C, but up to 14.9 ± 4.4 °C). Such cool temperatures at low paleolatitude (5-20°) are additional evidence of high elevation of at least 1 km. The vegetation consisted of Devonian pteridophytic progymnosperms, evidenced by rare foliar spurs and common woody root traces.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 4","pages":"Article 100287"},"PeriodicalIF":2.0,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145157622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-05DOI: 10.1016/j.jop.2025.100286
Guang Yang , Zhen-Yu Wang , Xing-Zhi Wang , Yun-Feng Zhang
The Permian marks a pivotal transition in Earth's evolutionary history, with oncolites offering insights into paleoenvironmental and evolutionary dynamics. This study documents the first occurrence of oncolites in the lower Permian (Sakmarian) Balikelike Formation in the Keping area, northwestern Tarim Basin, China. Integrated lithofacies analysis, geochemistry, and multi-scale observations reveal that the Balikelike Formation at the Subashi section comprises a complete third-order sequence, with two layers of oncolites developed in the highstand systems tract. These oncolites, predominantly developed on marl and interbedded with mudstone, exhibit elliptical, cap-shaped, hemispherical, and thin-plated morphologies. Fluorescence microscopy exhibits yellow-green fluorescence in dark laminae, while SEM identifies fossilized filamentous cyanobacteria. Geochemical data — Sr isotopes, weathering index values, and Sr/Ba ratios — suggest that oncolites develop in a warm, humid, and high-salinity environment with limited terrestrial input. The oncolite proliferation coincides with the initial magmatic phase of the Tarim Large Igneous Province, evidenced by negative carbon isotope excursions and the lower 87Sr/86Sr ratios compared to global seawater, signaling an interglacial warming phase. Volcanic activity likely curtailed the Asselian–Sakmarian glaciation in the Tarim Basin earlier than elsewhere, with carbon emissions, climate warming, and eutrophication, driving massive occurrence of oncolite.
{"title":"Characteristics, genesis, and paleoenvironmental significances of oncolites in the lower Permian (Cisuralian) Balikelike Formation from the northwestern Tarim Basin, China","authors":"Guang Yang , Zhen-Yu Wang , Xing-Zhi Wang , Yun-Feng Zhang","doi":"10.1016/j.jop.2025.100286","DOIUrl":"10.1016/j.jop.2025.100286","url":null,"abstract":"<div><div>The Permian marks a pivotal transition in Earth's evolutionary history, with oncolites offering insights into paleoenvironmental and evolutionary dynamics. This study documents the first occurrence of oncolites in the lower Permian (Sakmarian) Balikelike Formation in the Keping area, northwestern Tarim Basin, China. Integrated lithofacies analysis, geochemistry, and multi-scale observations reveal that the Balikelike Formation at the Subashi section comprises a complete third-order sequence, with two layers of oncolites developed in the highstand systems tract. These oncolites, predominantly developed on marl and interbedded with mudstone, exhibit elliptical, cap-shaped, hemispherical, and thin-plated morphologies. Fluorescence microscopy exhibits yellow-green fluorescence in dark laminae, while SEM identifies fossilized filamentous cyanobacteria. Geochemical data — Sr isotopes, weathering index values, and Sr/Ba ratios — suggest that oncolites develop in a warm, humid, and high-salinity environment with limited terrestrial input. The oncolite proliferation coincides with the initial magmatic phase of the Tarim Large Igneous Province, evidenced by negative carbon isotope excursions and the lower <sup>87</sup>Sr/<sup>86</sup>Sr ratios compared to global seawater, signaling an interglacial warming phase. Volcanic activity likely curtailed the Asselian–Sakmarian glaciation in the Tarim Basin earlier than elsewhere, with carbon emissions, climate warming, and eutrophication, driving massive occurrence of oncolite.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 4","pages":"Article 100286"},"PeriodicalIF":2.0,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144925424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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