Journal of Palaeogeography最新文献

{"title":"Spatio-temporal variability in microfossil and geochemical records of Cenomanian-Turonian oceanic anoxic event-2: a review","authors":"","doi":"10.1016/j.jop.2024.06.002","DOIUrl":"10.1016/j.jop.2024.06.002","url":null,"abstract":"<div><div>The Cenomanian-Turonian boundary oceanic anoxic event (OAE-2; Bonarelli event; ∼94 Ma) is associated with a species turnover in the marine calcareous microfossil record, widespread marine anoxia, black shale deposition and positive δ¹³C excursions. This study reviews 141 CTBE sites globally, aiming to understand micropaleontological, geochemical, and sedimentological expressions of OAE-2. There is a clear palaeogeographic and palaeobathymetric heterogeneity in the development of OAE-2 marine anoxia. A majority of the documented OAE-2 sites are from deep marine environments. The calcareous nannoplankton and benthic foraminifera record a diversity decline, while planktic foraminifera shows community level shifts and no major mass extinction. The variability of total organic carbon in OAE-2 sediments across sites (&lt;1 to &gt;10 wt. %) and the δ¹³C profiles (diachronous) have been attributed to different mechanisms of anoxia development. The increased primary “productivity model” gains support from productivity proxies (e.g., Ba, P, Cu, Ni), redox-sensitive elements (e.g., Mn, Mo, U, V, As), and eutrophic genera (e.g., benthic foraminifera <em>Gabonita</em> spp., calcareous nannofossils <em>Biscutum</em> spp. and <em>Zeugrhabdotus</em> erectus). The enhanced organic carbon “preservation model” in stratified (semi) restricted basins gains support from sites with lower enrichment of redox-sensitive elements and oligotrophic flora and fauna in the OAE-2 records. Geochronology of the Caribbean and the High Atlantic Large Igneous Province events (CLIP and HALIP) mark them as likely triggers of the OAE-2 related global perturbation of marine biogeochemistry. Volcanic triggers may have caused climate warming, altered hydrological cycles, enhanced continental weathering, shifts in ocean circulation, and nutrient flows. Addressing knowledge gaps, further research is urged, utilizing innovative proxies, and exploring underrepresented depositional systems to comprehensively understand OAE-2 onset and biotic crisis.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 646-674"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141401880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sedimentary environment shift and organic matter enrichment mechanism in response to volcanic ash influence: A case study of the Permian Lucaogou Formation, Santanghu Basin, NW China","authors":"Miao Yu ,&nbsp;Gang Gao ,&nbsp;Miao Liu ,&nbsp;Hui Liang ,&nbsp;Ji-Lun Kang ,&nbsp;Xiong-Fei Xu ,&nbsp;Xin-Ying Zhao","doi":"10.1016/j.jop.2024.07.003","DOIUrl":"10.1016/j.jop.2024.07.003","url":null,"abstract":"<div><div>The second member of the Lucaogou Formation (P₂l₂) in the Tiaohu and Malang Sags of the Santanghu Basin (study area) underwent periodic volcanic activity and frequent lithological changes. This study comprehensively analyzed the organic geochemistry, mineral composition, organic matter (OM) types, volcanic cycle, and palaeoenvironment of shale in the study area. Techniques such as total organic carbon (TOC), rock pyrolysis (Rock-Eval), organic petrology, scanning electron microscopy (SEM) with energy-dispersive spectrum (EDS) analysis, X-ray diffraction (XRD), trace elements, and saturated hydrocarbon gas chromatography and mass spectrometry (GC–MS) were employed. The findings suggest that limited terrigenous input during the sedimentary period of the P₂l₂ led to the deposition of a distinctive mixture of volcanic ash (felsic) and carbonate (dolomite and calcite), with a low average clay mineral content of 6%. The P₂l₂ shale emerged as a high-quality source rock, predominantly composed of type I and II kerogens, with moderate OM maturity. The deposition environment was characterized by hot and arid conditions, high salinity, and intensive reducibility, which was favorable for algae development and conducive to OM preservation. Notably, two lamalginite types, labeled as lamalginite “A” and lamalginite “B,” were identified. Lamalginite “B”-rich shales were deposited in a hotter and drier climate compared to lamalginite “A”-rich shales. Lamalginite “B”- rich shale inexhibited high levels of C₂₈ regular sterane and β-carotenes, distinguishing it from lamalginite “A”-rich shale. A comprehensive analysis involving organic petrology, SEM, sedimentary environment, and biomarker characteristics suggests that lamalginite “B” may be a salt-tolerant green alga, while lamalginite “A” may be a cyanobacterium. Finally, an OM enrichment model for the P₂l₂ shale was established.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 793-822"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141699379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetostratigraphy and paleoenvironmental record of late Cenozoic sediments in the Taiyuan Basin, North China","authors":"Zhi-Qiang Feng ,&nbsp;Qian Li ,&nbsp;Wei Han ,&nbsp;Kun-Yuan Ma ,&nbsp;Yong-Jiang Liu ,&nbsp;Rong-Zhu Wei ,&nbsp;Yan-Wei Du ,&nbsp;Yong Lei ,&nbsp;Guang-Hui Li","doi":"10.1016/j.jop.2024.09.001","DOIUrl":"10.1016/j.jop.2024.09.001","url":null,"abstract":"<div><div>The Taiyuan Basin is of importance for intraplate tectonic deformation in North China and contains Cenozoic strata with a maximum thickness of 3800 m. A ∼853.5-m-deep borehole (ZK01) with an overall core recovery rate of 85.09% was drilled at Yuci (37°35′37ʺN, 112°39′47ʺE) in the central Taiyuan Basin, to obtain high-resolution records of paleomagnetism, paleoclimatic and paleoenvironmental conditions, and depositional environment of the sediments. The obtained magnetic polarity sequence consists of 13 normal and 12 reverse zones, which correspond to C1n–C4An.2n of the geomagnetic polarity time scale. Magnetostratigraphic data show that the evolution of ZK01 core covers the interval from 8.1 Ma to the present, and the bottoms of Pliocene, Quaternary, and Middle Pleistocene were identified in Taiyuan Basin, with a sedimentary accumulation rate ranging from 62.5 m/Ma to 175.9 m/Ma. Geochemical data reveal that the source rocks in the study area underwent intense weathering and the sediments mainly formed in a semi-arid and oxygen-rich conditions. In addition, paleoclimatic changes occurred at ∼7 Ma, 3.8 Ma, and 1.7 Ma, which can be closely related to the tectonic uplift of the Loess Plateau and Tibetan Plateau, as well as the variations in the Asian monsoon and associated regional and global climatic change.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 971-992"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemistry of cherts from the northern Jiangxi region, South China: Implication for paleoenvironment","authors":"Guo-Liang Xie ,&nbsp;Gao-Jie Zhou ,&nbsp;Yu-Yong Sun ,&nbsp;Yan-Ran Hu ,&nbsp;Wei-Duo Hao","doi":"10.1016/j.jop.2024.07.002","DOIUrl":"10.1016/j.jop.2024.07.002","url":null,"abstract":"<div><div>The extensive bedded cherts deposited during the Ediacaran–Cambrian (E–C) transition period play a crucial role in understanding the geological evolution of this period, yet the origin of these cherts remains disputed. Here, we present new geochemical data for cherts of the Piyuancun (PYC) Formation deposited during the Late Ediacaran and the Hetang (HT) Formation deposited during the Early Cambrian in northern Jiangxi region, Lower Yangtze region, South China. The PYC cherts contain a small amount of monaxons sponge spicules and radiolarian fragments, while the HT cherts lack siliceous organism evidence. Major and trace element analysis, coupled with discriminant diagrams, indicate a possible shift in redox conditions of seawater during the E–C transition in the northern Jiangxi region. The shift suggests a change from weakly–moderately restricted euxinic conditions to strongly restricted euxinic conditions. Furthermore, the location of both cherts are distant from the source area of siliceous organisms. Fossil evidence, as well as the values of Fe/Ti and Fe/(Mn+Ti), Eu anomalies, Post-Archean Australian Shale (PAAS) normalized REE+Y patterns, and various discriminant diagrams, support the conclusion that the PYC and HT cherts originated primarily from direct seawater precipitation, with the PYC cherts exhibiting weak hydrothermal evidence. Upwelling contributes to the formation of HT cherts and organic matter (OM) accumulation. Ocean acidification, triggered by OM degradation and biodegradation processes during the E–C transition period, leads to the extensive silica precipitation and preservation. These results enhance our understanding of the geological processes during the E–C transition.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 823-838"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141610351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The “underfilled trinity model” of foreland basins revisited: reality or myth?","authors":"Xiu-Mian Hu ,&nbsp;Eduardo Garzanti ,&nbsp;Juan Li ,&nbsp;Marcelle BouDagher-Fadel ,&nbsp;Giovanni Coletti ,&nbsp;An-Lin Ma ,&nbsp;Wen-Dong Liang ,&nbsp;Wei-Wei Xue","doi":"10.1016/j.jop.2024.07.001","DOIUrl":"10.1016/j.jop.2024.07.001","url":null,"abstract":"<div><div>The “<em>underfilled trinity</em>” model of foreland-basin stratigraphy was proposed based on the observation that the initial sedimentary stages along the western and northern front of the western and central Alps were represented by shallow-water carbonates (Calcaires à Nummulites) overlain by hemipelagic marls (Marnes Bleues) and capped by siliciclastic turbidites (Grès d’Annot). Subsequently, this model has been widely accepted and applied in foreland basins worldwide. We here re-investigated the Eocene-Oligocene sedimentary succession of the Western Alps to check its validity. Major geological features of this region include: i) the existence of a Cretaceous-Eocene unconformity spanning more than 25 Myr in the studied sections; ii) a virtually synchronous age of the Calcaires à Nummulites, Marnes Bleues, and Grès d’Annot formations across the Western Alps; iii) a long-term deepening-upward trend, from inner to outer ramp, documented by the Calcaires à Nummulites, followed by the pelagic Marnes Bleues and by the Grès d’Annot turbidites; iv) the provenance of the Grès d’Annot Formation from the Maures-Estérel Massif and/or Corsica-Sardinia block in the south, rather than from the Alpine orogen in the east. By integrating field observations, sedimentological, biostratigraphic, and provenance analyses, we found the Eocene “underfilled foreland” model too simplistic and inadequate to explain the basin evolution in the western Alpine region. Based on the alternative scenario proposed herein, the Annot and Barrême basins formed in the late Eocene (40-35 Ma) in an extensional/transtensional setting during a period of major change in tectonic stress fields across western Europe on the upper plate of the Apennine subduction.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 675-705"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141610352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A remarkable decade of learning and sharing knowledge through the Journal of Palaeogeography (JoP) (2014–2024): Reminiscences from an Associate Editor-in-Chief","authors":"","doi":"10.1016/j.jop.2024.06.005","DOIUrl":"10.1016/j.jop.2024.06.005","url":null,"abstract":"<div><div>In this editorial, an Associate Editor-in-Chief of the <em>Journal of Palaeogeography</em> (JoP) reminisces his publication experience in JoP during the period 2014-2024. 1) During a period of nine years, he contributed eight review articles, three discussions, two replies, one book review, one glossary, and one tribute to the first Editor-in-Chief Prof. Zeng-Zhao Feng. His contributions totaled 534 printed pages. 2) His contributions examined 19 different domains, such as landslides, submarine fans, seismites, SSDS, hyperpycnites, rivers, etc. 3) His contributions coincided with the formative years of JoP. 4) The impact of his articles is evident from the Stats published by ResearchGate. For example, his review article “The Landslide Problem” has reached 11,611 Reads and 186 Citations after nine years of publication in 2015. 5) In 2023, the CNKI (China National Knowledge Infrastructure) recognized his article “Submarine fans: a critical retrospective (1950-2015)” as the Top-1% most-highly cited publications in the <em>Journal of Palaeogeography</em> published during a 10–year survey period: 2012–2022. 6) He was inducted as a Founding Member of the International Society of Palaeogeography (ISP) at Changping District of China University of Petroleum (Beijing), Beijing on July 16, 2022. 7) His JoP editorship during the past 10 years has been the most challenging, inspiring, and rewarding experience of his global scientific journey spanning over six decades (1962–2024).</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 1029-1040"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141552498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Upwelling current and its relationship to the enrichment of organic matter in the Lower Silurian Longmaxi Formation, northern Chongqing–western Hubei area, southern China","authors":"Jun-Jun Shen ,&nbsp;Jia-Kai Yan ,&nbsp;Peng-Wan Wang ,&nbsp;Yu-Man Wang ,&nbsp;Lin Zhou ,&nbsp;Yu-Bing Ji ,&nbsp;Min Xu","doi":"10.1016/j.jop.2024.08.005","DOIUrl":"10.1016/j.jop.2024.08.005","url":null,"abstract":"<div><div>Upwelling currents play a crucial role in the enrichment of organic matter, yet the mechanisms driving this process remain incompletely understood due to methodological and data resolution limitations. In this paper, we employ a combination of biostratigraphic classification, qualitative methods, and quantitative methods to systematically analyze the sedimentological and geochemical characteristics of the Lower Silurian Longmaxi Formation in the northern Chongqing–western Hubei area, southern China. The relationship between the upwelling currents and organic matter enrichment in the shale of the Longmaxi Formation is investigated. Results indicate that the upwelling currents in the study area were primarily influenced by the foreland flexure process. From the Rhuddanian (flexure–sedimentation stage) to the Aeronian (flexure–migration stage), the more intense tectonic activity led to gradual opening of the barrier between the South Qinling Ocean and the Yangtze Platform, resulting in an increase in the influx of the oceanic current. The upwelling currents significantly contributed to the organic matter production, albeit without substantially affecting the preservation conditions. Throughout the succession of the Longmaxi Formation, the organic matter content decreased gradually from the passive continental margin to the foreland flexural stagnant basin, which was mainly due to deterioration of the preservation conditions as a result of sea level fall and increased terrigenous input. Despite the increase in the upwelling currents, they did not decisively control the organic matter enrichment. Spatially, during the Rhuddanian to Aeronian period, the organic matter content decreased similarly from the passive continental margin to the foreland flexural stagnant basin, influenced by reduced organic matter production caused by weakening of the upwelling currents and the worsening preservation conditions caused by sea-level fall. The terrigenous input had a relatively minor impact. The results of this study provide new insights into the role of upwelling currents in the organic matter enrichment within the Longmaxi Formation, overcoming previous methodological and resolution barriers.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 993-1015"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three-dimensional reconstruction of Late Miocene Trapa from eastern Zhejiang Province, China: Insights into its phytogeography and evolution","authors":"Liang Xiao ,&nbsp;Man Yuan ,&nbsp;De-Shuang Ji ,&nbsp;Li-Yan Guo ,&nbsp;Xiang-Chuan Li ,&nbsp;Xing Wang ,&nbsp;Jia-Nan Wang ,&nbsp;Jia-Qi Liang ,&nbsp;Mei-Ting Wang","doi":"10.1016/j.jop.2024.08.002","DOIUrl":"10.1016/j.jop.2024.08.002","url":null,"abstract":"<div><div>Abundant plant fossils were found in the Upper Miocene Shengxian Formation, eastern Zhejiang Province, China, among which <em>Trapa</em> belongs to a dominant population. The fossil fruits of <em>Trapa</em> were well preserved with abundant details. However, due to compaction during fossilization, <em>Trapa</em> fruits were often flattened, leading to the loss of some characteristic features. Thereby, a bias in taxonomic and phylogenetic studies would occur when such studies were based on these fruit fossils. In this study, we present the first quantitative three-dimensional reconstruction of compressed <em>Trapa</em> fruit fossils to restore their original morphology prior to burial. This approach provides a novel perspective for the identification and classification of compressed fruit fossils. The three-dimensional reconstruction of <em>Trapa</em> fruit fossils enabled accurate comparisons with extant species. We subsequently identified it as a new species, named <em>Trapa</em> <em>radiatiformis</em> L. Xiao sp. nov., revealing differences from previously known taxa of <em>Trapa</em>. Importantly, our comparison suggests that the long lower horns and residual stalk may represent inherent characteristics of early <em>Trapa</em> fruits. However, these traits gradually degenerated during fruit evolution, resulting in morphological simplification during geological time. <em>T. radiatiformis</em> with primitive features exhibits good resemblance to <em>Trapa</em> <em>natans</em> fruit characteristics, which means it may be an ancestor of <em>T. natans.</em> We summarize the palaeogeographic distribution of fossil <em>Trapa</em> using previously published literature and demonstrate that the genus was most prosperous in the Miocene and exhibited the same distribution as that at present. Additionally, through detailed morphological comparisons between <em>Trapa</em> and <em>Hemitrapa</em> fruits, along with phylogenetic analysis within the <em>Primotrapa</em> genus itself, we propose a homology between <em>Trapa</em> and <em>Hemitrapa</em>, suggesting that they could have a common ancestor.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 954-970"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Provenance and tectonic setting of sandstones of the Lomas Coloradas Formation, Cabullona Group, Sonora, México: Constraints on petrography and geochemistry","authors":"J. Madhavaraju ,&nbsp;D.G. Noriega-Montoya ,&nbsp;E. Ramirez-Montoya ,&nbsp;C.M. González-León ,&nbsp;John S. Armstrong-Altrin","doi":"10.1016/j.jop.2024.07.005","DOIUrl":"10.1016/j.jop.2024.07.005","url":null,"abstract":"<div><div>The sedimentary rocks of the Cabullona Group are well exposed in the Cabullona Basin of northeastern Sonora, México, which represent syntectonic sedimentation associated with Laramide-style deformation during the Campanian−early Maastrichtian. The sandstones of the Lomas Coloradas Formation deposited at the upper part of the Cabullona Group. Petrography and geochemical (major, trace, and rare earth elements) studies were carried out on the sandstones to interpret the palaeoweathering, provenance, and tectonic setting of the Lomas Coloradas Formation sandstones. Most of the sandstone modal analysis data plotted in the QFL and QmFLt ternary diagrams fall into the fields of dissected arcs and recycled orogens, respectively. Geochemically the sandstones are classified as litharenites while few samples plot into the arkosic field. The chondrite-normalized REE diagrams for sandstones have LREE-enriched, relatively flat HREE patterns with negative Eu anomalies. CIA values and the A‒CN‒K diagram indicate a low intensity of chemical weathering in the source area. The tectonic setting diagram suggests both arc and rift settings for the studied sandstones. The bivariate and ternary diagrams and elemental ratios suggest a felsic source for the Lomas Coloradas Formation. The average REE patterns of the studied sandstones are comparable with REE patterns of the granite from the Caborca block, the rhyolite and granite of the Tarahumara Formation, and the Mesozoic felsic volcanic rocks. The modeled mixture of 40% Proterozoic granite, 30% Triassic arc, 10% Jurassic arc, and 20% Laramide arc represents the probable source rocks for the Lomas Coloradas Formation.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 839-861"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolution of a confined gravelly river to a braided-meandering river in the Late Cretaceous Khasi group, southern Shillong plateau, NE India","authors":"Adrita Choudhuri ,&nbsp;Prem Raj Uddandam ,&nbsp;Debarati Nag","doi":"10.1016/j.jop.2024.08.003","DOIUrl":"10.1016/j.jop.2024.08.003","url":null,"abstract":"<div><div>This paper intends to unravel the depositional condition of the Basal Conglomerate/Jadukata Formation and the Lower Mahadek Formation in southern Shillong Plateau, NE India deposited during the Late Cretaceous period. The studied succession is entirely siliciclastics in composition and was built up on the Precambrian basement rocks. State-of-art facies analysis and palaeocurrent evidence helped us to reconstruct the palaeogeography and palaeoenvironment. The facies tracts reveal that frequent hyperconcentrated mass flow deposits dominated the proximal part of the river channels. Gradually, the river evolved to a sandy braided and finally mud-dominated, meandering system. The river channel changed its pattern through onlapping and progressive elimination of the accommodation space created by the tectonic subsidence/upliftment. Major shifts in palaeocurrent direction at different stages of the river evolution confirm the role of tectonics on the river channel evolution. QFL detrital modes of the sandstones reflecting lithic wacke composition and the recycled orogeny corroborate the interpretation. Rapid lateral and vertical facies transition suggests a pull-apart type basin due to ongoing rifting. Geochemical analyses also show signatures of the overlapping tectonic conditions supporting the pull-apart basin model.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 754-774"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}