Journal of Palaeogeography最新文献

{"title":"Palaeogene Sequoia leaves from Yunnan Province, China and their biogeographical significance","authors":"Ren-Dan Yang ,&nbsp;Ai Song ,&nbsp;Li Wang ,&nbsp;Li-Rong Jia ,&nbsp;Shi-Hu Li ,&nbsp;Shi-Tao Zhang ,&nbsp;Quan-Fu Wu ,&nbsp;Yi Gao ,&nbsp;Jiang-Bo Meng ,&nbsp;Xuan-Rong Yao ,&nbsp;Min Deng ,&nbsp;Shu-Feng Li ,&nbsp;Tao Su","doi":"10.1016/j.jop.2025.100322","DOIUrl":"10.1016/j.jop.2025.100322","url":null,"abstract":"<div><div><em>Sequoia</em> was widely distributed across the Northern Hemisphere during the Cenozoic, yet our understanding of its biogeographic history remains limited due to relatively scarce fossil records in certain regions, particularly East Asia. A new <em>Sequoia</em> leaf fossil record from the Late Eocene to Early Oligocene in Yunnan Province of southwestern China displays morphological similarity to the fossil species <em>S. maguanensis</em>, such as an alternate leaf arrangement with a decurrent base, straight epidermal cell walls, and stomata surrounded by four subsidiary cells. Using the MaxEnt model and <em>S. sempervirens</em> (the only extant species of <em>Sequoia</em>) as a reference, we identified optimal potential distribution areas for <em>Sequoia</em> from the Palaeocene to the Pliocene. Our results indicate that <em>Sequoia</em>, which thrived in warm and humid conditions, progressively shifted its range southward as global temperatures declined from the Eocene to the Pliocene, contracting its habitat towards lower latitudes. Our analysis suggests that <em>Sequoia</em> likely originated in East Asia during the Early Cretaceous and subsequently spread to North America via the Bering Land Bridge. During the Palaeocene, it extended its range to Greenland and Svalbard, eventually reaching western Europe during the Eocene. In the Oligocene, <em>Sequoia</em> was widespread across Europe and reached Siberia, later expanding from East Asia to the Mediterranean and northern Thailand by the Miocene. Quaternary glaciations led to its near-complete disappearance in Eurasia and North America, with only remnant populations surviving along the western coast of the United States. This study also highlights the role of morphological stasis in <em>Sequoia</em> alongside the intensification of the monsoon climate as key factors contributing to its eventual disappearance in southwestern China.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 2","pages":"Article 100322"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145969135","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}

{"title":"Spatial slip rate partitioning along the Xianshuihe Fault Zone, eastern Tibetan Plateau","authors":"Jun Ma ,&nbsp;Zheng-Fang Li ,&nbsp;Ben-Gang Zhou ,&nbsp;Ming-Ming Wang ,&nbsp;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 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.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 1","pages":"Article 100297"},"PeriodicalIF":2.0,"publicationDate":"2026-01-01","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}

{"title":"The first fossil flower of Malpighiaceae from India sheds light on the historical biogeography of a mostly Neotropical family","authors":"Ashif Ali ,&nbsp;Rafael Felipe de Almeida ,&nbsp;Mahasin Ali Khan ,&nbsp;Raman Patel ,&nbsp;Rajendra Singh Rana","doi":"10.1016/j.jop.2025.100313","DOIUrl":"10.1016/j.jop.2025.100313","url":null,"abstract":"<div><div>A fossil flower affinity to an extinct Malpighiaceae taxon, recovered from the early Eocene (∼55–52 Ma) of Gurha Opencast Lignite Mine, Rajasthan, western India, helps to underscore the evolutionary significance of this angiosperm lineage in the Indian Cenozoic history. Based on several macromorphological traits, a new fossil genus and species of Malpighiaceae, named <em>Eomalpighia indica</em> Ali, R.F. de Almeida, and Khan gen. et sp. nov., is proposed. Additionally, a continental ancestral range reconstruction was performed using the generic molecular phylogeny of Malpighiaceae and the <em>BioGeoBEARS</em> package for historical biogeography to discuss the phylogenetic placement of this new fossil and its significance for Malpighiaceae biogeography. The fossil specimen is characterized by one anterior petal and four lateral petals, eglandular; one posterior sepal and four lateral sepals, clawed at the base, eglandular, elliptic; four stamens, free, anthers with two thecae; presence of gynoecium in the center with a trilobed apex. The newly described fossil flower is best placed as an ancestor of the tribe Acridocarpeae due to its unique morphology and fossil distribution. The ancestral range reconstruction evidenced that Malpighiaceae likely had two different dispersal waves from the Neotropics to the Paleotropics, taking place at the beginning (55.0–45.0 Ma) and the end (52–50 Ma) of the Eocene Climate Optimum Maximum. The first wave dispersed through Antarctica, and the second wave through the Boreotropics. This study provides insights into the taxonomy, evolutionary history, morphological evolution, and paleoecological implications of Malpighiaceae lineages in India.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 1","pages":"Article 100313"},"PeriodicalIF":2.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976469","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}

{"title":"Palaeogeography and its controls on organic carbon accumulation in the Wufeng–Longmaxi formations of Chongqing, southeastern Sichuan Basin, southwestern China","authors":"Yan-Wen Shao ,&nbsp;Feng-Hua Zhao ,&nbsp;Feng-Xian Jin ,&nbsp;Zhen-Sheng Shi ,&nbsp;Qun Zhao ,&nbsp;Shi-Long Kang ,&nbsp;Long-Yi Shao","doi":"10.1016/j.jop.2025.100314","DOIUrl":"10.1016/j.jop.2025.100314","url":null,"abstract":"<div><div>The Upper Ordovician Wufeng Formation and Lower Silurian Longmaxi Formation are important target strata for shale gas exploration in the Sichuan Basin, China. In this paper, the sedimentary facies and palaeogeography of the two formations in Chongqing area have been analyzed, and total organic carbon (TOC) contents are correlated with the sedimentary facies to prospect the favorable areas for shale gas exploration. According to the lithological characteristics and sedimentary structures, five sedimentary facies are identified, i.e., siliceous deep-water shelf, muddy deep-water shelf, calcareous shallow-water shelf, muddy shallow-water shelf, and silty-muddy shallow-water shelf facies, respectively. The palaeogeography reconstruction is based on the lithological distribution in the study area. The lower part of Wufeng Formation was developed with the muddy deep-water shelf, siliceous deep-water shelf, and calcareous shallow-water shelf facies. The Guanyinqiao Member, representing the upper part of Wufeng Formation, was developed with the transition from siliceous deep-water shelf and muddy deep-water shelf facies to a domination of muddy shallow-water shelf and calcareous shallow-water shelf facies, which was deposited during the glacial-induced global regression. The Lower Member of Longmaxi Formation was characterized by the expansion of siliceous deep-water shelf facies and contraction of muddy shallow-water shelf and calcareous shallow-water shelf facies, signifying a rapid sea level rise associated with global warming. The Upper Member of Longmaxi Formation was developed with muddy shallow-water shelf facies, with the expansion of calcareous shallow-water shelf and silty-muddy shallow-water shelf facies. The shales with higher TOC content tend to be developed in the siliceous deep-water shelf and muddy deep-water shelf facies that were distributed in the Nanchuan, Shizhu, Yongchuan, and Wuxi areas. The results of lithofacies palaeogeography reconstruction have a certain significance to predict shale-gas target areas in Wufeng and Longmaxi formations of Chongqing.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 1","pages":"Article 100314"},"PeriodicalIF":2.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145736710","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}

{"title":"Ecological stability of late Maastrichtian benthic foraminifera amidst Deccan volcanism","authors":"Subham Patra ,&nbsp;Kebenle Kesen ,&nbsp;Gerta Keller ,&nbsp;Thierry Adatte ,&nbsp;Jahnavi Punekar","doi":"10.1016/j.jop.2025.100317","DOIUrl":"10.1016/j.jop.2025.100317","url":null,"abstract":"<div><div>The late Maastrichtian witnessed profound disruptions in biogeochemical cycles, leading to the fifth mass extinction at the Cretaceous–Paleogene (K/Pg) boundary. At Bidart section (France), the final ∼60 kyr of the Maastrichtian coincide with mercury (Hg) peaks, low magnetic susceptibility, evidence of biological stress and taphonomic alteration in planktic foraminifera, indicative of an ocean acidification event. While this event primarily appears to be a surface-ocean phenomenon, previous studies also documented a minor rise in benthic foraminiferal test fragmentation beginning 0.5 m below the K/Pg boundary, with a pronounced spike at the boundary itself.</div><div>A detailed investigation of benthic foraminifera in biozone CF1 at Bidart section (France) reveals a diverse and balanced assemblage preceding the K/Pg boundary, with minimal taphonomic alterations. At the K/Pg boundary, infaunal populations diminished, diversity declined sharply, test fragmentation intensified, yet paradoxically, the absolute abundance of genera rose markedly. Preferential preservation is evident in the dominance of robust taxa (<em>Cibicidoides</em> spp.<em>, Coryphostoma</em> spp.), while a high fragmentation index reflects strong taphonomic dissolution and time-averaging. A plausible explanation for this could be CO₂-rich waters mixing into the ocean interior over 100–1000 years, driving dissolution during the ∼10,000-year deposition of the K/Pg boundary red clay. The stark contrast between the planktic and benthic census and morphometric data at Bidart section clearly constrains any Deccan-related calcification stress to the surface mixed layer. Lastly, the integrated planktic and benthic considerations re-emphasize a need to carefully separate taphonomic signals from true ecological stress.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 1","pages":"Article 100317"},"PeriodicalIF":2.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145789735","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}

{"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 ,&nbsp;Zi-Hui Sheng ,&nbsp;Fang-Yu Li ,&nbsp;Ning Lu ,&nbsp;Meng-Yu Chen ,&nbsp;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":"2026-01-01","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}

{"title":"First record of Araucaria with leafy shoots and reproductive organs from the Lower Cretaceous of NW China and its historical biogeography","authors":"Ai-Jing Li ,&nbsp;Bao-Xia Du ,&nbsp;Jing Zhang ,&nbsp;Jing Peng ,&nbsp;Ming-Chen Zhang ,&nbsp;Pei-Hong Jin ,&nbsp;Shao-Hua Lin ,&nbsp;Yi-Qiao Fu ,&nbsp;Jing-Jing Cai","doi":"10.1016/j.jop.2025.100310","DOIUrl":"10.1016/j.jop.2025.100310","url":null,"abstract":"<div><div>The modern Gondwanan genus, <em>Araucaria</em>, exhibited a worldwide distribution during its early evolution in the late Mesozoic. However, the scarcity of fossil records restricted exploring its early radiation and evolution. A new species, <em>Araucaria gansuensis</em> sp. nov. was described based on well-preserved leafy shoots associated with female cones, deciduous pollen cones and bract-scale complexes from the Lower Cretaceous in Northwest China. Maximum parsimony analysis revealed that the phylogenetic position of <em>A. gansuensis</em> is within the basal clade of Sect. <em>Eutacta</em>. Moreover, palaeobiogeographic analysis suggested that <em>Araucaria</em> possibly originated in the low latitudes of the Pangea and formed differentiation centers in Laurasia (East Asia) and Gondwana (South America) in the Middle Jurassic. Furthermore, with the breakup of Pangea, <em>Araucaria</em> rapidly radiated globally, and exhibited a more extensive distribution in the Northern Hemisphere during the Cretaceous. The discovery of <em>A. gansuensis</em> as a significant representative has unveiled a pathway for the dispersion of <em>Araucaria</em> in East Asia and Europe. Subsequently, <em>Araucaria</em>, which belonged to a more primitive lineage, started declining and facing extinction in the Northern Hemisphere in the Early Paleocene due to factors such as geographic isolation, climatic variations, and expansion and dominance of angiosperms.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 1","pages":"Article 100310"},"PeriodicalIF":2.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145839171","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}

{"title":"Organic lithofacies and its reservoir characteristics of lacustrine shales of the Dongyuemiao Member in the Jurassic Ziliujing Formation, eastern Sichuan Basin","authors":"Ming-Yang Wei ,&nbsp;Wang Chen ,&nbsp;Xing-Zhi Wang ,&nbsp;Zhi-Dong Bao ,&nbsp;De-Ming Zeng ,&nbsp;Jia-Hao Kang ,&nbsp;Yang Li ,&nbsp;Kai-Ming Liu ,&nbsp;Fei Huo","doi":"10.1016/j.jop.2025.100309","DOIUrl":"10.1016/j.jop.2025.100309","url":null,"abstract":"<div><div>This study investigates the reservoir properties and main controlling factors of different organic lithofacies in the Jurassic Dongyuemiao Formation lacustrine shales, eastern Sichuan Basin. Based on lithofacies classification, the spatial characteristics and physical properties of the reservoirs, along with the primary controlling factors, were analyzed using core observation, scanning electron microscopy (SEM), low-temperature nitrogen adsorption, and other techniques. The results indicate that: 1) In the eastern Sichuan Basin, the Dongyuemiao Member is predominantly composed of clay minerals and quartz, which are the main mineral constituents of the lacustrine shales. Minor amounts of calcite, feldspar, dolomite, pyrite, and rhodochrosite are also present. Four main lithofacies were identified within the study area: argillaceous shale with high-medium TOC (Ⅰ₂), mixed shale with low-medium TOC (Ⅱ₁), sacrilegious-silt mixed shale with medium-low TOC (Ⅱ₂), and argillaceous siltstone with low TOC (Ⅲ₂). 2) The shale microstructure is characterized by micropores, primarily comprising intergranular pores between clay minerals and organic-matter pores. Intragranular dissolution pores, notably within shell fragments, are locally developed. Microfractures are mainly observed as intra-layer shale fractures and fractures along the edges of shell fragments. 3) High organic matter abundance (&gt;1 %), high clay mineral content (&gt;40 %), and moderate carbonate mineral content (&lt;10 %) in the shale of the study area contribute to the development of pores. In contrast, high quartz and feldspar mineral content (&gt;50 %) and excessively high (&gt;12 %) or low (&lt;8 %) carbonate mineral content inhibit shale pore development. 4) A comprehensive analysis shows that the argillaceous-silt mixed shale with medium-low TOC (Ⅱ₂) is the most favorable lithofacies for reservoir development, followed by argillaceous shale with high-medium TOC (Ⅰ₂). The mixed shale with lower-medium TOC (Ⅱ₁) is less favorable, and the argillaceous siltstone with low TOC (Ⅲ₂) is the poorest. Considering the vertical distribution of lithofacies in the Dongyuemiao Member, it is concluded that the middle-upper part of the Dong 2 submember is the most prospective reservoir interval in the study area.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 1","pages":"Article 100309"},"PeriodicalIF":2.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145617798","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}

{"title":"Grallatorid–eubrontid tridactyl track assemblages from Lower Jurassic, Sichuan Province, China: Insights into theropod diversity, locomotion and behavior","authors":"Li-Da Xing ,&nbsp;Shan Jiang ,&nbsp;Qi-Yan Chen ,&nbsp;Yong Ye ,&nbsp;Guang-Zhao Peng ,&nbsp;Anthony Romilio ,&nbsp;Hendrik Klein ,&nbsp;Yan-Yi Gong","doi":"10.1016/j.jop.2025.100311","DOIUrl":"10.1016/j.jop.2025.100311","url":null,"abstract":"<div><div>The Sichuan Basin in southwestern China is home to the most extensive theropod track record in the Lower Jurassic of China, comprising a range of minute-to medium-sized tracks that form the grallatorid–eubrontid (GE) plexus. The majority of these had previously been discovered in the Ma’anshan Member of the Ziliujing Formation. New material described herein is from the Wuli tracksite that suggests a flourishing paleoecological scene in a temporary waterfront habitat. Upon reviewing the GE plexus at different scales, we consider the locomotion style of these early theropod trackmakers, which likely included the ‘grounded-running’ gait of extant birds, as well as the possibility of a tail trace that may be related to intra- or interspecific interactions.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 1","pages":"Article 100311"},"PeriodicalIF":2.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145736712","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}

{"title":"Organic matter accumulation in limestone-marl alternations of the middle Permian Maokou Formation, Sichuan Basin, China, and its response to the interglacial–glacial transition","authors":"Feng-Bin Liu ,&nbsp;Liang-Biao Lin ,&nbsp;Bo-Lin Zhang ,&nbsp;Yu Yu ,&nbsp;Yong Dan ,&nbsp;Si-Yu Liu","doi":"10.1016/j.jop.2025.100312","DOIUrl":"10.1016/j.jop.2025.100312","url":null,"abstract":"<div><div>The deposition of limestone-marl alternations (LMAs) with elevated organic matter (OM) content within the Middle Permian (Guadalupian) Maokou Formation of the Sichuan Basin, China, was influenced by the interglacial–glacial transition. However, the mechanisms of OM accumulation remain unclear. This study examines OM accumulation in the first member of the Maokou Formation (i.e., the Mao I Member) from the Hegou and Zaodu sections using multiple geochemical proxies, with a focus on its response to climatic shifts during the interglacial–glacial transition. OM accumulation was primarily influenced by this climatic transition through two interrelated processes: (1) by regulating the intensity of chemical weathering (Rb/Sr) in nearshore shallow-platform environments, which in turn controlled terrigenous nutrient input (Ti/Al); and (2) by enhancing upwelling in distal deeper waters (Cd/Mo), thereby stimulating primary productivity (OCAR, PAR, Cu_XS, and Ni_XS). These mechanisms overcame the typical constraints of an oxygenated carbonate platform setting (where Ce anomalies are mostly &lt;1.3), exerting a stronger control on OM accumulation than redox conditions. As glacial conditions intensified, the dominant mode of OM accumulation in the Mao I Member shifted from a detrital-driven regime—characterized by high terrigenous input (Ti/Al) and clay-mediated preservation (Al₂O₃)—to a hybrid system jointly regulated by both detrital input and upwelling-related nutrient delivery (Cd/Mo). In this latter phase, enhanced upwelling compensated for the decline in terrigenous nutrients. OM accumulation persisted even under oxygenated bottom-water conditions. This finding contrasts with the anoxia-dependent models typical of high OM shales and underscores the predominance of productivity over preservation factors in this icehouse carbonate platform. The transition toward glacial conditions is evidenced by the decreasing Rb/Sr ratios, indicating weakened chemical weathering, and declining Ti/Al ratios, signifying reduced terrigenous input. Our findings elucidate how multi-factor interactions govern OM accumulation in mixed carbonate–clastic systems and provide valuable constraints for predicting the stratigraphic distribution and quality of potential hydrocarbon source rocks in such settings.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 1","pages":"Article 100312"},"PeriodicalIF":2.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145736859","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}