Pub Date : 2026-01-19DOI: 10.1016/j.jop.2026.100326
Zhong-Yang Chen , Mongkol Udchachon , Hathaithip Thassanapak , Jian-Feng Lu , Xiang Fang , Wen-Jie Li , Clive Burrett
Late Silurian to Early Devonian conodonts are first documented from the marl–limestone alternations, with biostromes and mud mounds, succession in the north of the Loei fold belt, in the Truong Son Terrane of the Indochina Composite Terrane in NE Thailand. Species found include Wurmiella excavata, Panderodus unicostatus, Zieglerodina eladioi, Belodella resima, Neopanderodus aequabilis, Belodella anomalis, and Icriodus? sp. indet. Seven major lithofacies of sedimentary rocks were identified and interpreted as shallower to deeper marine environments in a warm, tropical zone. The sequence was deposited to the east of a Silurian rhyolitic volcanic arc with which it interdigitates and is regarded as a part of an arc or back-arc basin. A Siluro-Devonian arc shows that this part of the Indochina Composite Terrane rifted away from Gondwana in or prior to the Silurian.
{"title":"First documentation of late Silurian and earliest Devonian (Lochkovian) conodonts from biostromes and mud mounds in Truong Son Terrane of the Indochina Composite Terrane: Geological significance","authors":"Zhong-Yang Chen , Mongkol Udchachon , Hathaithip Thassanapak , Jian-Feng Lu , Xiang Fang , Wen-Jie Li , Clive Burrett","doi":"10.1016/j.jop.2026.100326","DOIUrl":"10.1016/j.jop.2026.100326","url":null,"abstract":"<div><div>Late Silurian to Early Devonian conodonts are first documented from the marl–limestone alternations, with biostromes and mud mounds, succession in the north of the Loei fold belt, in the Truong Son Terrane of the Indochina Composite Terrane in NE Thailand. Species found include <em>Wurmiella excavata</em>, <em>Panderodus unicostatus</em>, <em>Zieglerodina eladioi</em>, <em>Belodella resima</em>, <em>Neopanderodus aequabilis</em>, <em>Belodella anomalis</em>, and <em>Icriodus</em>? sp. indet. Seven major lithofacies of sedimentary rocks were identified and interpreted as shallower to deeper marine environments in a warm, tropical zone. The sequence was deposited to the east of a Silurian rhyolitic volcanic arc with which it interdigitates and is regarded as a part of an arc or back-arc basin. A Siluro-Devonian arc shows that this part of the Indochina Composite Terrane rifted away from Gondwana in or prior to the Silurian.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 2","pages":"Article 100326"},"PeriodicalIF":2.0,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079875","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 : 2026-01-01DOI: 10.1016/j.jop.2025.100313
Ashif Ali , Rafael Felipe de Almeida , Mahasin Ali Khan , Raman Patel , Rajendra Singh Rana
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 Eomalpighia indica 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 BioGeoBEARS 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.
在印度西部拉贾斯坦邦Gurha露天褐煤矿的始新世早期(~ 55-52 Ma)发现的一种已灭绝的malpiighiaceae分类群的花化石,有助于强调这一被子植物谱系在印度新生代历史中的进化意义。基于几个宏观形态特征,提出了一种新的麻瓜科化石属和种,命名为Eomalpighia indica Ali, R.F. de Almeida, and Khan gen. et sp. nov.。此外,利用Malpighiaceae的一般分子系统发育和历史生物地理学的biogeobars软件包进行了大陆祖先范围的重建,讨论了该新化石的系统发育定位及其对Malpighiaceae生物地理学的意义。化石标本的特征是一个前花瓣和四个侧花瓣,腺状;一后萼片和四侧萼片,爪状在基部,腺状,椭圆形;四雄蕊,离生,花药具二花萼;中心有雌蕊,先端有三叶。由于其独特的形态和化石分布,新描述的化石花最适合作为tribe Acridocarpeae的祖先。祖先范围的重建表明,从新热带到古热带可能有两次不同的扩散波,分别发生在始新世气候最适最大值的开始(55.0 ~ 45.0 Ma)和结束(52 ~ 50 Ma)。第一波穿过南极洲,第二波穿过北方热带。本研究对印度麻瓜科植物的分类、进化历史、形态演化和古生态意义等方面提供了新的认识。
{"title":"The first fossil flower of Malpighiaceae from India sheds light on the historical biogeography of a mostly Neotropical family","authors":"Ashif Ali , Rafael Felipe de Almeida , Mahasin Ali Khan , Raman Patel , 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}
Pub Date : 2025-12-23DOI: 10.1016/j.jop.2025.100322
Ren-Dan Yang , Ai Song , Li Wang , Li-Rong Jia , Shi-Hu Li , Shi-Tao Zhang , Quan-Fu Wu , Yi Gao , Jiang-Bo Meng , Xuan-Rong Yao , Min Deng , Shu-Feng Li , Tao Su
Sequoia 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 Sequoia leaf fossil record from the Late Eocene to Early Oligocene in Yunnan Province of southwestern China displays morphological similarity to the fossil species S. maguanensis, 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 S. sempervirens (the only extant species of Sequoia) as a reference, we identified optimal potential distribution areas for Sequoia from the Palaeocene to the Pliocene. Our results indicate that Sequoia, 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 Sequoia 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, Sequoia 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 Sequoia alongside the intensification of the monsoon climate as key factors contributing to its eventual disappearance in southwestern China.
{"title":"Palaeogene Sequoia leaves from Yunnan Province, China and their biogeographical significance","authors":"Ren-Dan Yang , Ai Song , Li Wang , Li-Rong Jia , Shi-Hu Li , Shi-Tao Zhang , Quan-Fu Wu , Yi Gao , Jiang-Bo Meng , Xuan-Rong Yao , Min Deng , Shu-Feng Li , 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":"2025-12-23","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}
Pub Date : 2025-12-22DOI: 10.1016/j.jop.2025.100321
Wen-Yi He , Yong-An Qi , Ming-Yue Dai , Zhen Zhang , Yao-Gang Du , Min Wang
Abundant fenestral fabrics are widely developed in microcrystalline dolomite, algal clump dolomite, and stromatolitic dolomite of Cambrian Stage 4 on southern North China Block. The paper aims to elucidate the genesis of fenestral fabrics and their relevance to palaeoenvironmental and palaeoclimatic conditions. The fenestral fabrics comprise micron-to millimetric (bird's-eye structures) and centimetric voids, predominantly infilled with calcite and gypsum, with minor occurrences of dolomite. Raman spectral data indicate that organic matter is more concentrated at the edges of fenestral fabrics than in the dolomite matrix or the fabric cores, suggesting that these structures may represent potential accumulation zones for gas bubbles, possibly linked to microbial decomposition. The dolomite sediments consolidated under the exposed, arid, and hot climate conditions, preserving these gas bubbles as micropores. Increased evaporation led to the desiccation and shrinkage of the dolomite sediments, which in turn enlarged the original micropores into larger voids, thereby creating the necessary space for the formation of fenestral fabrics. The calcite and gypsum crystals in fenestral fabrics were interpreted as products of significant Ca2+ loss from the dolomite matrix during the transformation of high-magnesium calcite to dolomite, coupled with the Ca2+ precipitation from high-salinity brine into fenestral fabrics. This rarely documented fabric type, defined by a dolomite matrix with calcite infill, contributes novel petrographic and geochemical evidence that refines current models of fenestral fabric formation, and supports new interpretations of palaeoenvironmental and palaeoclimatic conditions in ancient evaporitic systems.
{"title":"Genesis of fenestral fabrics in tidal flat dolomites of Cambrian Stage 4: Evidence from Western Henan, Southern North China Block","authors":"Wen-Yi He , Yong-An Qi , Ming-Yue Dai , Zhen Zhang , Yao-Gang Du , Min Wang","doi":"10.1016/j.jop.2025.100321","DOIUrl":"10.1016/j.jop.2025.100321","url":null,"abstract":"<div><div>Abundant fenestral fabrics are widely developed in microcrystalline dolomite, algal clump dolomite, and stromatolitic dolomite of Cambrian Stage 4 on southern North China Block. The paper aims to elucidate the genesis of fenestral fabrics and their relevance to palaeoenvironmental and palaeoclimatic conditions. The fenestral fabrics comprise micron-to millimetric (bird's-eye structures) and centimetric voids, predominantly infilled with calcite and gypsum, with minor occurrences of dolomite. Raman spectral data indicate that organic matter is more concentrated at the edges of fenestral fabrics than in the dolomite matrix or the fabric cores, suggesting that these structures may represent potential accumulation zones for gas bubbles, possibly linked to microbial decomposition. The dolomite sediments consolidated under the exposed, arid, and hot climate conditions, preserving these gas bubbles as micropores. Increased evaporation led to the desiccation and shrinkage of the dolomite sediments, which in turn enlarged the original micropores into larger voids, thereby creating the necessary space for the formation of fenestral fabrics. The calcite and gypsum crystals in fenestral fabrics were interpreted as products of significant Ca<sup>2+</sup> loss from the dolomite matrix during the transformation of high-magnesium calcite to dolomite, coupled with the Ca<sup>2+</sup> precipitation from high-salinity brine into fenestral fabrics. This rarely documented fabric type, defined by a dolomite matrix with calcite infill, contributes novel petrographic and geochemical evidence that refines current models of fenestral fabric formation, and supports new interpretations of palaeoenvironmental and palaeoclimatic conditions in ancient evaporitic systems.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 2","pages":"Article 100321"},"PeriodicalIF":2.0,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145981600","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 : 2025-12-19DOI: 10.1016/j.jop.2025.100320
Yuan-Yuan Tang , Yu Shi , Guo-Dong Jin
The Early Paleozoic tectonic evolution of the South China Block (SCB) remains a subject of considerable debate, particularly regarding whether it resulted from intracontinental orogeny or the subduction–collision process. The Wuyi Terrane (WYT), located at the center of the Wuyi–Yunkai orogen, plays a crucial role in understanding the petrogenesis of the Early Paleozoic magmatic products and tectonic evolution of the SCB. This study presents zircon U–Pb ages, geochemical analyses, and Lu–Hf isotopic data for the Fufang and Guixi granitic plutons located within the WYT. Zircon U–Pb dating results indicate that these granites were formed during the Early Paleozoic (ca. 437–436 Ma), and negative zircon εHf(t) values (−20.7 to −6.2) suggest an ancient crustal source for the granites. These contemporaneous granites, characterized by peraluminous to strongly peraluminous compositions, are classified as high-K calc-alkaline to shoshonitic series and are recognized as highly fractionated S-type granites. They exhibit enrichment in Rb, Th, U, K, and Pb, while showing depletions in Ba, Sr, Nb, Ta, P, and Ti. The observed variations in Eu anomalies suggest differing source compositions and magmatic processes between the two plutons. Based on the geochemical and isotopic evidence, we propose that the Fufang granites originated from the partial melting of crustal meta-sedimentary rocks, without the contribution of mantle-derived materials, whereas the Guixi granites resulted from the partial melting of a heterogeneous crustal source predominantly composed of meta-sedimentary rocks, with a minor contribution from meta-igneous rocks. The granites underwent varying degrees of feldspar-dominated fractional crystallization throughout their magmatic evolution. In conjunction with their post-collisional geochemical characteristics and the regional tectonic frameworks, we suggest that the Early Paleozoic tectonic evolution of the SCB was characterized by intracontinental orogeny, with the formation of the Fufang and Guixi granites occurring during the intracontinental lithospheric extensional phase that followed collisional compression.
{"title":"Petrogenesis of the Early Paleozoic S-type granites within the Wuyi Terrane: Implications for the tectonic evolution of the South China Block","authors":"Yuan-Yuan Tang , Yu Shi , Guo-Dong Jin","doi":"10.1016/j.jop.2025.100320","DOIUrl":"10.1016/j.jop.2025.100320","url":null,"abstract":"<div><div>The Early Paleozoic tectonic evolution of the South China Block (SCB) remains a subject of considerable debate, particularly regarding whether it resulted from intracontinental orogeny or the subduction–collision process. The Wuyi Terrane (WYT), located at the center of the Wuyi–Yunkai orogen, plays a crucial role in understanding the petrogenesis of the Early Paleozoic magmatic products and tectonic evolution of the SCB. This study presents zircon U–Pb ages, geochemical analyses, and Lu–Hf isotopic data for the Fufang and Guixi granitic plutons located within the WYT. Zircon U–Pb dating results indicate that these granites were formed during the Early Paleozoic (ca. 437–436 Ma), and negative zircon <em>ε</em><sub>Hf</sub>(t) values (−20.7 to −6.2) suggest an ancient crustal source for the granites. These contemporaneous granites, characterized by peraluminous to strongly peraluminous compositions, are classified as high-K calc-alkaline to shoshonitic series and are recognized as highly fractionated S-type granites. They exhibit enrichment in Rb, Th, U, K, and Pb, while showing depletions in Ba, Sr, Nb, Ta, P, and Ti. The observed variations in Eu anomalies suggest differing source compositions and magmatic processes between the two plutons. Based on the geochemical and isotopic evidence, we propose that the Fufang granites originated from the partial melting of crustal meta-sedimentary rocks, without the contribution of mantle-derived materials, whereas the Guixi granites resulted from the partial melting of a heterogeneous crustal source predominantly composed of meta-sedimentary rocks, with a minor contribution from meta-igneous rocks. The granites underwent varying degrees of feldspar-dominated fractional crystallization throughout their magmatic evolution. In conjunction with their post-collisional geochemical characteristics and the regional tectonic frameworks, we suggest that the Early Paleozoic tectonic evolution of the SCB was characterized by intracontinental orogeny, with the formation of the Fufang and Guixi granites occurring during the intracontinental lithospheric extensional phase that followed collisional compression.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 2","pages":"Article 100320"},"PeriodicalIF":2.0,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145969134","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 : 2025-12-17DOI: 10.1016/j.jop.2025.100319
Arya Farjand , Qi-Gao Jiangzuo , Zhao-Qun Zhang , Paul Rummy , Mehdi Khoshnamvand , Shun-Dong Bi
The Amphicyonidae are an extinct group of large carnivorans that appeared during the Late Eocene in North America but thrived during the Miocene epoch in Eurasia. In China, Amphicyon has been recognized with three species; however, all are identified from limited material. A partial cranium discovered from the late Middle Miocene strata of Xin'an, Henan, central China, significantly improves our understanding of Amphicyon in China, Europe, and North America. It suggests the uniquity of this Amphicyon species, namely Amphicyon zhinu sp. nov., which is distinguishably smaller in size and differs in the morphology of its maxillary teeth. Therefore, the presence of these four different species of Amphicyon in North China during the Middle Miocene Climate Optimum verifies the high diversity and suggests an evolutionary divergence.
{"title":"New species of Amphicyon (Mammalia, Carnivora) from the Middle Miocene strata of Xin'an, Henan, China","authors":"Arya Farjand , Qi-Gao Jiangzuo , Zhao-Qun Zhang , Paul Rummy , Mehdi Khoshnamvand , Shun-Dong Bi","doi":"10.1016/j.jop.2025.100319","DOIUrl":"10.1016/j.jop.2025.100319","url":null,"abstract":"<div><div>The Amphicyonidae are an extinct group of large carnivorans that appeared during the Late Eocene in North America but thrived during the Miocene epoch in Eurasia. In China, <em>Amphicyon</em> has been recognized with three species; however, all are identified from limited material. A partial cranium discovered from the late Middle Miocene strata of Xin'an, Henan, central China, significantly improves our understanding of <em>Amphicyon</em> in China, Europe, and North America. It suggests the uniquity of this <em>Amphicyon</em> species, namely <em>Amphicyon zhinu</em> sp. nov., which is distinguishably smaller in size and differs in the morphology of its maxillary teeth. Therefore, the presence of these four different species of <em>Amphicyon</em> in North China during the Middle Miocene Climate Optimum verifies the high diversity and suggests an evolutionary divergence.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 2","pages":"Article 100319"},"PeriodicalIF":2.0,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145981601","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}
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.
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 (Cibicidoides spp., Coryphostoma 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.
{"title":"Ecological stability of late Maastrichtian benthic foraminifera amidst Deccan volcanism","authors":"Subham Patra , Kebenle Kesen , Gerta Keller , Thierry Adatte , 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 CO<sub>2</sub>-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":"2025-12-06","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}
Pub Date : 2025-12-06DOI: 10.1016/j.jop.2025.100318
Rong-Heng Tian , Ben-Zhong Xian , Qian-Ran Wu , Peng Chen , Naveed Ur Rahman , Lin Zhao , Peng-Yu Wang , Wen-Miao Zhang
Understanding the evolution of the segmented synsedimentary fault linkage, which controls the accommodation development, sediment infill, and stratigraphic architecture, is essential for reconstructing rift histories and exploring natural resources. This study investigates the tectono-sedimentary processes in the steep slope of the Dongying Depression within the Bohai Bay Basin rift system, eastern China by utilizing three-dimensional seismic and drilling data. A classification scheme for non-coaxial extensional fault linkage styles is proposed, categorizing them into two types—partial linkage and through-going hard linkage—with eight subtypes based on geometric architectures, evolutionary stages, and segment-scale activity. Statistical analysis of the length and separation distance of the main border fault (the Chennan Fault) reveals that non-coaxial linkage systems are pervasive along the northern rift margin of the Dongying Depression. These systems controlled the development of its irregular zigzag geometry. Furthermore, analysis of non-coaxial convergent fault linkage processes provides the most plausible explanation for the initial morphology of the large paleo-gullies observed on the steep slope. Seismic-geomorphologic mapping and borehole dataset allow us to constrain the spatial and architectural variability of depositional systems along the rift margin. The results demonstrate that non-coaxial fault linkage processes control deep-water depositional types: basinal fans dominate during partial linkage phases, while nearshore subaqueous fans develop under through-going linkage conditions. Non-coaxial fault segment activity influences sediment input directions: uniform fault activity promotes longitudinal transport systems, whereas heterogeneous activity controls oblique delivery along dominant fault segments. This study enhances the understanding of non-coaxial fault systems and their sedimentary responses, providing a reliable basis for hydrocarbon exploration in the steep slopes of lacustrine rift basins.
{"title":"Control of deep-water sedimentation on rift margin by non-coaxial fault linkage system: a case study from the steep slope of the Dongying Depression, Bohai Bay Basin, China","authors":"Rong-Heng Tian , Ben-Zhong Xian , Qian-Ran Wu , Peng Chen , Naveed Ur Rahman , Lin Zhao , Peng-Yu Wang , Wen-Miao Zhang","doi":"10.1016/j.jop.2025.100318","DOIUrl":"10.1016/j.jop.2025.100318","url":null,"abstract":"<div><div>Understanding the evolution of the segmented synsedimentary fault linkage, which controls the accommodation development, sediment infill, and stratigraphic architecture, is essential for reconstructing rift histories and exploring natural resources. This study investigates the tectono-sedimentary processes in the steep slope of the Dongying Depression within the Bohai Bay Basin rift system, eastern China by utilizing three-dimensional seismic and drilling data. A classification scheme for non-coaxial extensional fault linkage styles is proposed, categorizing them into two types—partial linkage and through-going hard linkage—with eight subtypes based on geometric architectures, evolutionary stages, and segment-scale activity. Statistical analysis of the length and separation distance of the main border fault (the Chennan Fault) reveals that non-coaxial linkage systems are pervasive along the northern rift margin of the Dongying Depression. These systems controlled the development of its irregular zigzag geometry. Furthermore, analysis of non-coaxial convergent fault linkage processes provides the most plausible explanation for the initial morphology of the large paleo-gullies observed on the steep slope. Seismic-geomorphologic mapping and borehole dataset allow us to constrain the spatial and architectural variability of depositional systems along the rift margin. The results demonstrate that non-coaxial fault linkage processes control deep-water depositional types: basinal fans dominate during partial linkage phases, while nearshore subaqueous fans develop under through-going linkage conditions. Non-coaxial fault segment activity influences sediment input directions: uniform fault activity promotes longitudinal transport systems, whereas heterogeneous activity controls oblique delivery along dominant fault segments. This study enhances the understanding of non-coaxial fault systems and their sedimentary responses, providing a reliable basis for hydrocarbon exploration in the steep slopes of lacustrine rift basins.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 2","pages":"Article 100318"},"PeriodicalIF":2.0,"publicationDate":"2025-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080283","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 : 2025-11-28DOI: 10.1016/j.jop.2025.100312
Feng-Bin Liu , Liang-Biao Lin , Bo-Lin Zhang , Yu Yu , Yong Dan , Si-Yu Liu
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, CuXS, and NiXS). These mechanisms overcame the typical constraints of an oxygenated carbonate platform setting (where Ce anomalies are mostly <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.
{"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 , Liang-Biao Lin , Bo-Lin Zhang , Yu Yu , Yong Dan , 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<sub>XS</sub>, and Ni<sub>XS</sub>). These mechanisms overcame the typical constraints of an oxygenated carbonate platform setting (where Ce anomalies are mostly <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 (Al<sub>2</sub>O<sub>3</sub>)—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":"2025-11-28","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}
Pub Date : 2025-11-27DOI: 10.1016/j.jop.2025.100311
Li-Da Xing , Shan Jiang , Qi-Yan Chen , Yong Ye , Guang-Zhao Peng , Anthony Romilio , Hendrik Klein , Yan-Yi Gong
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.
{"title":"Grallatorid–eubrontid tridactyl track assemblages from Lower Jurassic, Sichuan Province, China: Insights into theropod diversity, locomotion and behavior","authors":"Li-Da Xing , Shan Jiang , Qi-Yan Chen , Yong Ye , Guang-Zhao Peng , Anthony Romilio , Hendrik Klein , 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":"2025-11-27","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}