Journal of Palaeogeography最新文献

{"title":"Cryo-paleosols and paleoclimate/cosmic archives in the Dry Valleys, Antarctica","authors":"William C. Mahaney ,&nbsp;Peeter Somelar","doi":"10.1016/j.jop.2025.100291","DOIUrl":"10.1016/j.jop.2025.100291","url":null,"abstract":"<div><div>Perhaps the most obscure and overlooked paleoenvironmental resource in Antarctica is the cryosol-paleosol record of the Dry Valleys, and the cryo-stratigraphy of the Palmer Peninsula, East Antarctica, and the islands. The Scientific Committee on Antarctic Research (SCAR) Committee in 2014 outlined a forward look for new initiatives and of the six priorities, the ‘Reveal Antarctica’s History’ focused on ‘rock and sediment records to know whether past climate states are fated to be repeated’. Of all the records available to us across the continent, the thinnest and most obscure, are found within cryo-paleosols and accompanying clastic rinds, the latter often embedded in pavements capping these ancient sentinels. An ancient pedostratigraphy, extending horizon group-to-horizon group reported here, offers unexpectedly strong post-∼15 Ma weathering and salt accumulation, interrupted by a recent airburst, presumably the BM (black mat) of 12.8 ka. Evidence for a cosmic event comes in the form of melted/welded, air-quenched, dendritic, Pt (Ir) coated, organic-fused grains and highly sheaved and plate-uplifted mineral surfaces. As shown here, Antarctic paleosols, housing both oxidized and Na-encrusted beds, shed light not only on paleoclimatic/ecologic histories that might be repeated, but this one cometary occurrence, reported for the first time in any Dry Valley paleosols, may well occur again, the next time with enough energy to destroy Earth’s atmosphere.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 4","pages":"Article 100291"},"PeriodicalIF":2.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219189","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":"Reversal of drainage patterns related to the Late Cretaceous topographic doming: a case study from eastern Gondwana basins of India","authors":"Sankar Kumar Nahak ,&nbsp;N. Prabhakar ,&nbsp;Santanu Banerjee ,&nbsp;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}

{"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 ,&nbsp;Zhi-Yuan He ,&nbsp;Sheng-Li Wang ,&nbsp;Yan Chen ,&nbsp;Yi-Fan Shi ,&nbsp;Guo-Hui Chen ,&nbsp;Shao-Wen Liu ,&nbsp;Yun-Jian Li ,&nbsp;Fei Xue ,&nbsp;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}

{"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":"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}

{"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 ,&nbsp;Lu-Qi Chen ,&nbsp;Hua-Ying Song ,&nbsp;Yu Qiao ,&nbsp;Su-Ping Li ,&nbsp;Wei Wu ,&nbsp;Chang-Song Lin ,&nbsp;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_EF and Zn_EF) 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_EF 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}

{"title":"Devonian-Carboniferous paleosols and tectonics of northwest China","authors":"Xue-Lian Guo ,&nbsp;Gregory J. Retallack ,&nbsp;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}

{"title":"Characteristics, genesis, and paleoenvironmental significances of oncolites in the lower Permian (Cisuralian) Balikelike Formation from the northwestern Tarim Basin, China","authors":"Guang Yang ,&nbsp;Zhen-Yu Wang ,&nbsp;Xing-Zhi Wang ,&nbsp;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 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.</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}

{"title":"New perspectives on the paleogeographic context of the Late Paleozoic Ice Age in Southwest Gondwana: U–Pb ages and sedimentary provenance data from the Paganzo Basin, Argentina","authors":"Julián D. Rolan ,&nbsp;Jonatan A. Arnol ,&nbsp;Francisco I. Lugo ,&nbsp;Norberto J. Uriz ,&nbsp;Andrea R. Bidone ,&nbsp;Carlos A. Cingolani ,&nbsp;Miguel A.S. Basei ,&nbsp;Maximiliano Naipauer","doi":"10.1016/j.jop.2025.100274","DOIUrl":"10.1016/j.jop.2025.100274","url":null,"abstract":"<div><div>This study presents the first detrital zircon U–Pb analysis alongside new petrographic data from the Jejenes Formation (Serpukhovian–Bashkirian), located on the southern margin of the Paganzo Basin, Argentina in Southwest Gondwana. The results were compared with previously published data from other synchronously deposited units to the north (Guandacol Formation) and northeast (Malanzán Formation). Notably, glacigenic deposits are present in both the Guandacol and Jejenes formations but absent in the Malanzán Formation. A sedimentary provenance analysis was conducted for the three units, highlighting similarities and differences among the depocenters, allowing for the reconstruction of the paleogeographic and topographic landscape of the Paganzo Basin during the Serpukhovian–Bashkirian time. The comparative analysis supports the idea of disconnection and isolation among the three depocenters with each unit recording predominantly proximal sources and the recycling of pre-Carboniferous substrate. Although certain similarities exist in the age distribution of the detrital zircon grains recorded for the Malanzán and Guandacol formations, this does not imply that the depocenters were connected or fed by the same source area. Instead, these successions were likely sourced from rocks with a similar geological history, resulting in comparable age distributions due to sediment recycling. Thus, the results support a conservative approach when estimating sedimentary provenance in ancient glacigenic deposits, emphasizing the need to evaluate local sediment sources. The absence of glacigenic deposits in the Malanzán Formation could be linked to a lower topography, linked to distinct tectonic histories in the Pie de Palo, Valle Fértil, and Chepes–Malanzán ranges, underscoring the role of tectonic inheritance in the distribution of glacial centers during the Late Paleozoic Ice Age.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 4","pages":"Article 100274"},"PeriodicalIF":2.0,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144914007","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":"Paleoenvironmental reconstruction and sequence biostratigraphy of Miocene transgressive–regressive sedimentary succession in the northern JDA, northern Malay Basin","authors":"Fatin Nur Adilah Md Idris ,&nbsp;Khairul Azlan Mustapha ,&nbsp;Fatin Izzati Mihnat ,&nbsp;Zainey Konjing","doi":"10.1016/j.jop.2025.100273","DOIUrl":"10.1016/j.jop.2025.100273","url":null,"abstract":"<div><div>The northern sector of the Malay Basin has long been underrepresented, leaving a gap in the understanding of its paleoenvironmental evolution. In addressing this gap, detailed biostratigraphic analysis based on palynology and foraminifera from two wells, i.e., Tj-1 and Tp-1, has been conducted to reconstruct the paleoenvironment during the Miocene age. The factors influencing their distribution were analyzed using a sequence biostratigraphic approach, complemented by environmental parameters such as grain size and organic matter content, supported by seismic and gamma ray logs. The findings reveal significant differences in the faunal distribution of the inner shelf and delta front between the two studied wells. The inner shelf in Tj-1 well is dominated by <em>Asterorotalia pulchella</em> and the accessory species <em>Pseudorotalia schroeteriana</em>. Whereas Tp-1 well, is dominated by <em>Pseudorotalia schroeteriana</em>, but <em>Asterorotalia pulchella</em> is absent. For delta front species, <em>Bigenerina</em> sp. and <em>Reophax</em> sp. are found throughout Tp-1 well. However, in Tj-1 well, the dominant assemblages are <em>Bigenerina</em> sp. and <em>Miliammina</em> sp. during Serravallian to Tortonian, and <em>Cavarotalia annectens</em> from Tortonian to Messinian. Furthermore, our study identifies a major transgressive–regressive (T–R) event during Langhian to Serravallian period, inferred from stratigraphic dating using the standard palynological zonation of Malay Basin (‘PR’ zone) with the age according to VIM (Vietnam–Indonesia–Malaysia) and SEA (Southeast Asia) cycles, which also highlights unconformities. This suggests that tectonic events have led to distinct fauna provinces within the Miocene biostratigraphic assemblages.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 4","pages":"Article 100273"},"PeriodicalIF":2.0,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144739523","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 optical textures of pyrobitumen in nature and its geological significance: revealed from the Ediacaran pyrobitumen in the central Sichuan Basin, SW China","authors":"Lian-Qiang Zhu ,&nbsp;Ze-Zhang Song ,&nbsp;Bing Luo ,&nbsp;Guang-Di Liu ,&nbsp;Wen-Zhi Zhao ,&nbsp;Qian-Qian Feng ,&nbsp;Ben-Jian Zhang ,&nbsp;Gang Zhou ,&nbsp;Xing-Wang Tian ,&nbsp;Dai-Lin Yang ,&nbsp;Lu-Ya Wu ,&nbsp;Lin Ma ,&nbsp;Mikhail Spasennykh ,&nbsp;Yi-Shu Li","doi":"10.1016/j.jop.2025.100271","DOIUrl":"10.1016/j.jop.2025.100271","url":null,"abstract":"<div><div>Some natural pyrobitumens exhibit optical anisotropy similar to mesophase asphalt, potentially recording critical geological information. However, the significance of their distinctive optical textures remains understudied. Anisotropic pyrobitumen in the Ediacaran Dengying Formation (central Sichuan Basin, southwestern China) provides a key example. This study investigates controls on pyrobitumen optical texture evolution using petrography, scanning electron microscopy, and U–Pb dating. Then, it discusses the relationship between these textures and anomalous thermal events by analyzing their spatial distribution and their geological significance. Results reveal that anisotropic pyrobitumen in Dengying Formation formed from oil cracking caused by Late Permian hydrothermal activity. These pyrobitumen can be divided into two categories based on the optical textures: fibrous and mosaic, reflecting distinct internal physical structures. Fibrous pyrobitumen exhibits more ordered aromatic layers than the mosaic type. Temperature primarily controls optical textures by regulating polycondensation reactions and pyrobitumen viscosity. Although the Gaoshiti and Moxi areas share similar burial histories, Gaoshiti is dominated by highly evolved fibrous pyrobitumen, while Moxi contains predominantly low-evolved mosaic pyrobitumen. This disparity indicates formation of anisotropic pyrobitumen was unrelated to normal burial temperatures but to hydrothermal activity. This study demonstrates that anisotropic pyrobitumen cannot form below 240 °C, even over extended durations. Consequently, in situ anisotropic pyrobitumen in deep strata serves as an indicator of paleo-thermal anomalies, with varying textures acting as proxies for relative temperatures within these events. Under identical geological settings, fibrous pyrobitumen typically records higher temperatures than mosaic pyrobitumen.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 4","pages":"Article 100271"},"PeriodicalIF":0.0,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144695053","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}