Journal of Palaeogeography最新文献

{"title":"Seismites of the Late Triassic Lockatong Formation, Pennsylvania, USA: implications for Newark Basin border fault movement","authors":"Edward L. Simpson ,&nbsp;Michael C. Wizevich ,&nbsp;David L. Fillmore","doi":"10.1016/j.jop.2024.12.005","DOIUrl":"10.1016/j.jop.2024.12.005","url":null,"abstract":"<div><div>Numerous soft-sediment deformation structures (SSDS) within thin-bedded, heterolithic lacustrine shoreline deposits of the Upper Triassic Tumble Falls Member, Lockatong Formation of eastern Pennsylvania, demonstrate liquefaction, fluidization and shearing features processes affecting sediment. This study employs thin-section analysis of SSDS to interpret them as probable seismites from the Triassic-Jurassic Newark Basin. Sedimentary structures include right-lateral offset of desiccation cracks and ichnofossils, thrust, reverse, and normal faults with mm-scale offsets, horsts and grabens, lateral spreads, and single and complex multiple networks of dikes and sills and associated sedimentary volcanoes, thin mudflows on a paleosurface linked to sediment dikes, load and flame structures, ball and pillow structures, recumbent folds, and incipient breccias. Dike fill consists of mudstone, angular sedimentary clasts, sandstone margins with mudstone cores, and plastically deformed sediment fill. The SSDS indicate that Late Triassic lacustrine shoreline sediments were subjected to forces, probably compressive with a minimal shear component reflected in the offset of the dikes and ichnofossils, that induced liquefaction followed by fluidization and vertical movement of fluids. Kinetic forces that altered sediment vertical stability, leading to deformation of the sediment included gravitationally unstable density gradients, vertical shear stress, and gravitational body forces. SSDS can be induced by seismic and aseismic processes. However, this unique combination of forces and resulting sedimentary structures indicate an origin by earthquake activity, likely produced by the nearby, active Newark Basin border fault system. The Lockatong Formation SSDS seismites improve our understanding via thin section analysis of the rheology and preservation potential of SSDS in lacustrine shoreline deposits, critical for the geologic history of Newark Basin, as well as the refinement for paleoseismic reconstruction in general.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 1","pages":"Pages 1-14"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134451","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 comparison of the proto-dolomite induced by cyanobacteria and halophilic bacteria: implications for dolomite-inducing microbe identification","authors":"Yan-Yang Zhao ,&nbsp;Xiang-Yu Wei ,&nbsp;Xiao Gao ,&nbsp;Na Guo ,&nbsp;Jie Li ,&nbsp;Kai-Ming Hu ,&nbsp;Chao Han ,&nbsp;Qi-Yu Wang ,&nbsp;Zuo-Zhen Han","doi":"10.1016/j.jop.2024.09.002","DOIUrl":"10.1016/j.jop.2024.09.002","url":null,"abstract":"<div><div>This study investigates the morphological and mineralogical characteristics of proto-dolomite induced by two specific microorganisms with varying lifestyles: the extremely halophilic bacterium <em>Vibrio harveyi</em> QPL2 and the cyanobacterium <em>Leptolyngbya boryana</em>. Halophilic bacterially-induced proto-dolomite (HBD) and cyanobacterially-induced proto-dolomite (CBD) were subjected to comprehensive characterization techniques, including X-ray diffraction, scanning electron microscopy, Focused Ion Beam, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The results indicate that both HBD and CBD exhibit a low degree of crystallinity and possess comparable molar ratios of MgCO₃ to CaCO₃. Moreover, neither of them exhibits the ordered structure of ideal dolomite. HBD and CBD exhibit notable distinctions in external morphology and internal structure. HBD forms a subunit aggregate with a less dense surface and numerous pinhole structures resulting from bacterial survival. In contrast, CBD adopts a bispherical shape with a relatively dense surface and minimal indications of cyanobacterial survival. Both HBD and CBD have an internal hollow structure. However, HBD is characterized by sparse population and loosely arranged subunits, while CBD features only a central cavity. Additionally, HBD particles are smaller compared to CBD particles. These morphological differences suggest that HBD primarily grows through bacterial surface-dependent processes, whereas the growth of CBD is not directly reliant on the surface of cyanobacteria. Compositionally, the weight percentage of crystalline water in CBD exceeded that of HBD with a value of 29.42 % compared to 5.9 %. This increase in internal crystalline water enables a faster conversion of CBD to the ordered ideal dolomite in a specific diagenetic environment. This study implies that the morphology and composition of microbial proto-dolomite may aid in identifying the type of dolomite-inducing microbes.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 1","pages":"Pages 277-290"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134025","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":"3D morphology of crab (Macrophthalmus japonicus) burrows from the Pearl River Delta front, China: The physicochemical factors, with implications for the rock record","authors":"Yuan-Yuan Wang ,&nbsp;Ya-Bin Zhang ,&nbsp;Song-Lin Gou ,&nbsp;Guo-Cheng Zhang","doi":"10.1016/j.jop.2024.09.004","DOIUrl":"10.1016/j.jop.2024.09.004","url":null,"abstract":"<div><div>Neoichnological characterization of modern depositional settings addresses the response of benthic animals to ecological conditions and their fluctuations, usually on a relatively short time scale. In this way, analogue models for interpretation of sedimentary strata in the geological record can be developed. <em>Macrophthalmus japonicus</em> (De Haan, 1835), a crab, is commonly found in the Pearl River Delta front of southern China. The burrows of <em>M. japonicus</em> are vertical or inclined, I-, U-, Y-, J- and L-shaped tubes, and these are imaged in 7.5-cm-diameter sediment cores. The cores were studied by X-ray radiography, computed tomography, and VG Studio MAX reconstruction to obtain three-dimensional images for elaborate morphological study. This crab's burrows are analogous to the trace fossil <em>Psilonichnus</em>. Several environmental parameters, i.e., sediment grain size and its total organic carbon (TOC) content, and turbidity and salinity of water, have been measured. The results indicated that <em>M. japonicus</em> prefers to live in mesohaline water with turbidity levels of 20–170 NTU, where bioturbation is more abundant. It prefers to occur in mud and silty sand substrates, with TOC content decreasing as particle size increases. The sedimentary environment, grain size and ichnofacies of analogical trace fossils <em>Psilonichnus</em> are discussed which supports the interpretation that <em>Psilonichnus</em> is a good indicator of delta front environments.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 1","pages":"Pages 203-220"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134023","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":"Basin inversion controls on diagenetic evolution of Lower Cretaceous non-marine succession: the English Wealden sandstones","authors":"Oladapo O. Akinlotan ,&nbsp;Sunday E. Okunuwadje ,&nbsp;Stuart J. Hatter","doi":"10.1016/j.jop.2024.12.003","DOIUrl":"10.1016/j.jop.2024.12.003","url":null,"abstract":"<div><div>Modelling the diagenetic history of a tectonically active basin is crucial for understanding the depositional and post-depositional processes including the evolution and development of porosity and permeability. This study describes the diagenetic imprints of the inverted Lower Cretaceous Weald Basin and examines the depositional and tectonic controls on the diagenetic, porosity and permeability evolution of its sandstones. Seventy-two representative sandstone samples from the Weald Basin were subjected to detailed microscopic (optical and scanning electron) analyses. The dominant early diagenetic fabrics include grain-coating detrital clays, degraded and dissolved detrital grains, and vermiform kaolinite pore-filling cement while uplift-related or telogenetic characteristics are mainly post-compactional pore-filling goethite and hematite cement. This work is significant because it presents the first diagenetic model of the Lower Cretaceous Wealden sandstones which can be very useful for understanding basins with similar depositional and tectonic settings.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 1","pages":"Pages 15-39"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134450","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 Camborygma Ichnofacies in a high-resolution sequence-stratigraphic framework for the Eocene palustrine-alluvial depositional interval of the Kutch Basin, India","authors":"Mohuli Das ,&nbsp;Sudipta Dasgupta ,&nbsp;Seema Singh ,&nbsp;Marcos Antônio Klunk ,&nbsp;Renzo D'souza","doi":"10.1016/j.jop.2024.12.001","DOIUrl":"10.1016/j.jop.2024.12.001","url":null,"abstract":"<div><div>The non-marine strata of the Ypresian Naredi Formation have been deposited and intermittently pedogenized after the culmination of the Early Eocene Climatic Optimum (EECO). This continental interval comprises intercalation of laterite and palaeosol horizons developed by cyclic episodes of erosion, subaerial exposure, and deposition. The palaeopedological analyses investigate the morphological and micromorphological features evidencing repeated subaerial exposure and consequently moderate to well-developed palaeosol horizons. The topmost laterite bed records an intensely bioturbated ichnofabric (consisting of the root traces and the composite ichnotaxa of lungfish aestivation burrows, <em>Macanopsis</em> (possible arachnid burrows), and <em>Skolithos</em>. The pedogenized shale horizons contain the paucispecific <em>Camborygma</em>-root trace ichnofabric with highly localized patchy preservation of <em>Camborygma</em> <em>symplokonomos</em>, <em>Camborygma eumekenomos</em>, and rhizoturbation. The ichnospecies variation of <em>Camborygma</em> along with the ichnofabric analyses led to the demarcation of stratigraphic horizons and evaluation of the palaeowater-table fluctuations vis-à-vis the low-order allocyclicity, the ethology of producers, and the depositional setting. The paucispecific suite of trace fossils refers to the <em>Camborygma</em> Ichnofacies, where the substrate is intermittently pedogenized and lateritized with upward increasing thickness of beds and intensity of pedogenesis, lateritization, ichnodiversity, and ichnoabundance. Hence, as an expression of high-frequency (interpreted as 5th-order) stratigraphic fluctuations within an early Falling Stage Systems Tract (FSST), a hot palaeoclimate with seasonality varying between humid inundated to dry desiccated conditions is interpreted with the palaeowater table being the base-level control. It culminates with the driest condition at the top with the thickest laterite development associated with the RAeMaS ichnofabric. With the onset of early transgression as documented in the overlying marine deposits of the Bartonian Harudi Formation, the top of the studied interval marks an induced subaerial unconformity.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 1","pages":"Pages 141-156"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134356","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":"First documentation of early Silurian conodonts from western Thailand and its geological implications","authors":"Zhong-Yang Chen ,&nbsp;Hathaithip Thassanapak ,&nbsp;Wen-Jie Li ,&nbsp;Xue-Jin Wu ,&nbsp;Mongkol Udchachon ,&nbsp;Xiang Fang ,&nbsp;Clive Burrett","doi":"10.1016/j.jop.2024.08.010","DOIUrl":"10.1016/j.jop.2024.08.010","url":null,"abstract":"<div><div>The early Silurian conodonts are firstly described and illustrated from western Thailand. Samples were collected from the Kroeng Kravia Forest Park area for conodont and lithofacies analyses. An upper Telychian Lower <em>Pterospathodus amorphognathoides amorphognathoides</em> Subzone is recognized for the studied succession. Three lithofacies were identified from the carbonate succession, including stromatolite–thrombolite limestone, nodular limestone, and red limestone. Both analyses on lithofacies and conodont assemblages indicate a deeper marine depositional environment. The conodont fauna in the study area is similar to that from Baoshan of Yunnan Province and Langao of Shaanxi Province in West China and resembles that from similar depositional environments in Australia, Laurentia, and peri-Gondwana, suggesting good connections among these regions by ocean currents.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 1","pages":"Pages 157-171"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134357","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":"Responses of non-marine deposits to fluctuating base level and their implications in the Precambrian sequence building: Late Neoproterozoic Girbhakar Sandstone, Rajasthan, India","authors":"Pradip Samanta ,&nbsp;Soumik Mukhopadhyay ,&nbsp;Arunava Sen ,&nbsp;Madhurya Roy","doi":"10.1016/j.jop.2024.10.002","DOIUrl":"10.1016/j.jop.2024.10.002","url":null,"abstract":"<div><div>The distinctive sedimentation patterns of the late Neoproterozoic Girbhakar Sandstone were investigated within the context of a Precambrian sedimentation system devoid of vegetation. This comprehensive study utilized an integrated approach, incorporating facies analysis, fluvial architectural elements analysis, and palaeocurrent analysis, to offer detailed insights into the controlling factors of sedimentology and depositional settings within the studied interval. Process-based facies analysis revealed thirteen distinct facies types organized into five associations, uncovering a diverse range of depositional palaeoenvironments — from alluvial fan and braided fluvial to transitional marine settings. An alluvial fan, dominated by debris flow and multiple ephemeral channels at the basin margin, emerged initially. The stratigraphic architecture of this alluvial fan and the associated ephemeral fluvial system was primarily influenced by water table fluctuations in arid to semiarid climatic conditions. A transition to a semi-perennial to perennial braided fluvial system occurred as the depositional slope decreased. However, the stratigraphic architecture of these fluvial systems exhibited distinctive variations in response to fluctuating base level rise. Notably, the basal segment, characterized by an unconformity below and a granular lag succeeded by wave-agitated sandstone above, represented the lowstand systems tract (LST). During the early LST, channel belts prograded at the northern distal end of upstream aggradational semi-perennial braided systems in response to the transgression of Girbhakar Sea from the north, aligning with the late Neoproterozoic Indian plate configuration. The coarsening upward deposits suggest a potential classification as a braid-delta, formed by a gradual rise in base level, low epeiric gradient, and episodic flashy discharges, which facilitate the downstream development of this deposit. During the late LST, the evolution of perennial fluvial systems resulted in braid-plain deposits throughout the study area, with a transitional marine unit at the downstream site. An accelerated rate of base level rise facilitated marine reworking, leading to the deposition of transitional marine sediments. The final phase of base level rise marked the cessation of terrestrial deposition, culminating in the submergence of the site underneath the sea. The study highlights the unique responses of alluvial sediments to diverse controlling factors along the deposition downslope. This enhances insights into Neoproterozoic alluvial sedimentation dynamics and the resulting stratigraphic architecture in time and space from a broad perspective.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 1","pages":"Pages 66-90"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134449","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":"Autocyclic switching processes and architecture of lobes in river-dominated lacustrine deltas","authors":"Zhen-Hua Xu ,&nbsp;Sheng-He Wu ,&nbsp;Piret Plink-Björklund ,&nbsp;Tao Zhang ,&nbsp;Da-Li Yue ,&nbsp;Qi-Hao Qian ,&nbsp;Qing Li ,&nbsp;Wen-Jie Feng","doi":"10.1016/j.jop.2024.12.004","DOIUrl":"10.1016/j.jop.2024.12.004","url":null,"abstract":"<div><div>River-dominated lacustrine deltas typically consist of multiple lobes due to autogenic lobe switching that occurs over short time scales. However, the switching patterns of multiple lobes in these deltas remain poorly understood, and the architectural features attributed to lobe switching are also lacking. By integrating Delft3D simulations, flume experiments, and modern deposit analysis, we proposed that autogenic lobe switching follows a cyclic pattern. Autocyclicity begins with the formation of an offshore lobe and concludes after a series of longshore lobe growth events, marked by longshore avulsions occurring along the sides of offshore distributary channels. Longshore avulsions follow a sequence that usually occurs earlier distally than proximally and subsequently occurs on one longshore side and then on the other side. Each lobe begins with rapid growth, which gradually slows and then stops once a channel avulsion is influenced by the backwater effect that triggers lobe switching. Three signals indicate lobe switching: a decrease in progradation rate, foreset slope steepening coupled with topset slope gentling, and the deposition of mud-dominated sediments. The number of autocyclic events never exceeds seven. The first two autocyclicities contribute to more than 55% of delta length and 70% of delta area. The lobes are separated by 1–6 stages of mud-dominated accretion beds that exhibit a downstream-inclined shape and convex-up or lateral overlapping pattern. This study conducts a coupled growth-geometric assessment to establish an architectural pattern for river-dominated lacustrine deltas. This architectural pattern offers valuable insights into predicting sandy lobe distribution in river-dominated lacustrine delta reservoirs, and the architecture of muddy accretion beds aids in predicting the rule of oil–water movement and distribution of remaining oil.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 1","pages":"Pages 126-140"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134446","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":"Paleomapping: Creating testable visual hypotheses of ancient worlds","authors":"Holger Petermann ,&nbsp;Annaka M. Clement ,&nbsp;Patrick M. Sullivan ,&nbsp;Hannah M. Bonner ,&nbsp;James W. Hagadorn","doi":"10.1016/j.jop.2024.11.003","DOIUrl":"10.1016/j.jop.2024.11.003","url":null,"abstract":"<div><div>The story of the Earth's changing landscapes is often told through paleogeographic maps. These images are some of the most accessible and widely used illustrations in the Earth sciences. However, no formal procedure for the creation of photorealistic paleomaps (i.e., paleosatellite images) exists. Using an example from the Late Jurassic of the Rocky Mountain region, we present a method for making paleoenvironmental and paleosatellite maps that is scalable, reproducible, testable, and incorporates peer review. The process includes a literature review followed by data-visualization, paleoenvironmental interpretation, peer-review, iterative revisions, and the creation of a false contour map and color gradient used to render a paleosatellite image. Paleosatellite images are photorealistic versions of paleoenvironmental maps that incorporate global climatic and tectonic information as well as principles of actualism; they can be made through comparison to analogous modern landscapes. An important component of this process is that the data maps that ground this paleomapping process allow evaluation of where paleoenvironmental interpretations are well-supported by outcrop and subsurface data, and where such visualization is highly interpretive – often because of lack of available rocks or studies in a given area. As such, our paleoenvironmental maps and paleosatellite images are testable pictorial hypotheses. By outlining a procedure that produces referenced, data-rich, and visually realistic maps, we hope to demystify the paleoenvironmental map-making process and improve accessibility of paleomaps for the broader geoscience community. Where resources and complementary data are available, such maps also have potential for georeferencing and integration with larger continent-scale paleogeographic maps.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 1","pages":"Pages 91-104"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134447","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":"Vertical variations in planar lamination of marine shale: Elucidating hydrodynamic changes during the Ordovician–Silurian transition on the Upper Yangtze Block","authors":"Zhen-Sheng Shi ,&nbsp;Tian-Qi Zhou ,&nbsp;Hui-Bo Song ,&nbsp;Yong-Bin Niu ,&nbsp;Sha-Sha Sun","doi":"10.1016/j.jop.2024.09.003","DOIUrl":"10.1016/j.jop.2024.09.003","url":null,"abstract":"<div><div>The hydrodynamics and their evolution on the Upper Yangtze Block during the Ordovician–Silurian transition period remain unclear. The present study is an assessment of how regional and global events may have influenced the hydrodynamic evolution based on a planar lamination investigation of the shales from the Upper Yangtze Block. Analyses of large thin sections and argon-ion polished thin sections using field emission-scanning electron microscopy (FE-SEM) showed that there are four types of planar lamination, namely, silty graded planar lamination (SGPL), silt–clay graded planar lamination (SCGPL), silt–clay interlaminated planar lamination (SCIPL), and paper-like planar lamination (PPL). SGPL is formed by turbidity current with a flow speed less than 15 cm/s. SCGPL is formed by turbidity currents with a flow speed less than 15 cm/s for normal grading type and 15–25 cm/s for alternating grading type. SCIPL has a continuum of sparsely spaced type, closely spaced type, and alternating type, which is formed by bottom current with an increasing flow speed from 15 to 25 cm/s to above 25 cm/s. PPL can be divided into normal grading and composite grading types. The former is formed by vertical settling, while the latter is formed by bottom current with a flow speed of 5–15 cm/s. Vertically, types of planar lamination varied from SGPL to PPL and then SCIPL manifesting the waxing and waning of flow speed with a positive excursion at graptolite biozone <em>Metabolograptus extraordinarius</em> (WF4) and a negative excursion at graptolite biozone <em>Persculptograptus</em> <em>persculptus (</em>LM1). The sudden decrease in flow speed across Linxiang and graptolite biozone <em>Paraorthograptus</em> <em>pacificus</em> (WF3) and the subsequent progressive increase from graptolite biozone <em>Akidograptus ascensus</em> (LM2) to graptolite biozone <em>Demirastrites triangulatus</em> (LM6) and to graptolite biozone <em>Stimulograptus sedgwickii</em> (LM8) during deposition of the Ordovician–Silurian transition succession on the Upper Yangtze Block were linked to the bulge uplift, the rapid subsidence, and the relaxation controlled by the Kwangsian orogeny. In contrast, the positive excursion at WF4 and the negative excursion at LM1 were strongly controlled by the Hirnantian Glaciation and global warming, respectively.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 1","pages":"Pages 221-244"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134452","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}