Journal of Palaeogeography最新文献

{"title":"Southern Tethys shelf evolution around the Cenomanian–Turonian OAE2: The Saharan Atlas (Algeria) depositional model","authors":"Madani Benyoucef ,&nbsp;Marcin Krajewski ,&nbsp;Mohamed Lassad Guendouz ,&nbsp;Mohammed Adaci ,&nbsp;Ashley Gumsley ,&nbsp;André Piuz ,&nbsp;Djamila Zaoui ,&nbsp;Imad Bouchemla ,&nbsp;Mariusz Salamon","doi":"10.1016/j.jop.2024.07.006","DOIUrl":"10.1016/j.jop.2024.07.006","url":null,"abstract":"<div><div>The present work, based on lithostratigraphy and biostratigraphy, is focused on ammonites, microfacies, and chemostratigraphic study (δ¹³C and δ¹⁸O) of the late Cenomanian–early Turonian sequence in the El Bayadh area (Saharan Atlas, Algeria). Five informal stratigraphic units (units 1 to 5) have been defined within the Rhoundjaïa Formation, which is subdivided into four ammonite biozones: the <em>Neolobites vibrayeanus</em>, the <em>Metoicoceras geslinianum</em>, the <em>Vascoceras cauvini</em>, and the <em>Choffaticeras sinaiticum</em> zones. The Cenomanian–Turonian boundary (CTB) is located at the limit between units 2 and 3. Field data and microscopic analysis have resulted in the recognition of fourteen microfacies types (MT 1 to MT 14) that are described in terms of depositional environments, and grouped into six main limestone and limestone–marl facies associations (FA 1–6), representing two different palaeosettings: (i) open shelf/ramp-type carbonate platform and (ii) isolated carbonate platform. The sequence stratigraphic analysis revealed two third-order depositional sequences (DS1 and DS2) covering a period of about 2.8 million years. The depositional model for the uppermost Cenomanian shows the presence of a rudist- and microbial-rich isolated carbonate platform, away from terrigenous influence, and surrounded by deep-water open shelf facies. The comparison of the isotopic fluctuation profile with those of various marine sites in the Tethyan Ocean shows synchronous global events.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 2","pages":"Pages 334-369"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143869229","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":"Sedimentary system and palaeogeographic evolution of Ordos Basin, northern China","authors":"Yan-Qin Guo ,&nbsp;Bai-Qiang Li ,&nbsp;Bo Li ,&nbsp;Wen-Hou Li ,&nbsp;Hong-Xia Cao ,&nbsp;Yun Liao ,&nbsp;Zhen-Zhen Wu ,&nbsp;Shi-Xiang Fei ,&nbsp;Qian Zhang ,&nbsp;Qiang Chen ,&nbsp;Ruo-Gu Wang ,&nbsp;Yao Ma ,&nbsp;Zhen Yuan ,&nbsp;Zhi-Chao Li ,&nbsp;Sheng Fu","doi":"10.1016/j.jop.2025.01.002","DOIUrl":"10.1016/j.jop.2025.01.002","url":null,"abstract":"<div><div>Extensive work on outcrops and drilling wells in the Ordos Basin, northern China, has been carried out over the past decades to study its depositional systems. Investigation of depositional environments, lithology, sedimentary structures, and fossils in the basin reveals that during the Changchengian and Jixianian periods, the depositional system transformed from the continental-nearshore environment to carbonate tidal flat. From the deposition period of Xinji to the Zhushadong formations, the western and southern margin of the basin evolved from sand flat to dolomite flat. The open platform dominated the basin during the deposition period from Mantou to the Sanshanzi formations. From the deposition period of Yeli to the Liangjiashan formations, the eastern and southern margins of the basin evolved from argillaceous dolomitic flat to dolomitic flat. The large-scale transgression in the deposition period of Majiagou Formation resulted in extensive shallow-water epicontinental deposits. In the deposition period of Fengfeng Formation, the western margin of the basin was dominated by platform margin slope and continental slope-trough deposits, while the southeastern and southern parts were mainly open-platform deposits. During the deposition period of Pingliang Formation, shoal deposits occurred on the platform margin in the southern part of the basin. During the deposition period of Beiguoshan Formation, the dominant open platform and platform foreslope deposits were only distributed in the southwestern corner of the basin. The Ordovician and Carboniferous strata were separated by a major unconformity and the Silurian to Devonian were missing in the basin. In the deposition period of Benxi Formation, a filling process and the deposition of tidal flat–lagoon–barrier island–shallow sea shelf occurred in the basin. During the deposition period of Taiyuan Formation, the range of the shallow sea-shelf sedimentation in the eastern part reduced. During the deposition period from Shanxi to the Zhifang formations, the delta and shallow lacustrine deposits developed. The depocenters migrated in different periods. From the deposition period of the Yanchang Formation to the Cretaceous, lacustrine, meandering rivers, braided rivers, and deltas dominated the basin. The maximum lacustrine transgression occurred in the deposition period of Chang 7 Member of the Yanchang Formation, which can be divided into 10 members with Chang 1 at the top and Chang 10 at the bottom. During the deposition period from Fuxian to the Anding formations, the meandering river, delta, and shallow lake deposits developed, and the depocenter of shallow lake varied. Deep lacustrine sediments developed in the deposition period of the Anding Formation. During the deposition period of the Fenfanghe Formation, alluvial fan deposits dominated, then transformed into a desert and shallow lake facies in the Cretaceous, which resulted in the shrinking of the depocenter.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 2","pages":"Pages 501-534"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143869315","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":"A moderate elevation and warm-humid climate of the Wulan Basin, NE Tibetan Plateau in the Middle Miocene indicated by Pueraria macrofossils","authors":"Zhen-Dong Cao,&nbsp;San-Ping Xie,&nbsp;Li-Ming Liu,&nbsp;Xiao-Mei Li,&nbsp;Si-Hang Zhang,&nbsp;Yun-Zhe Zhang,&nbsp;De-Fei Yan","doi":"10.1016/j.jop.2024.08.012","DOIUrl":"10.1016/j.jop.2024.08.012","url":null,"abstract":"<div><div>The phased uplift of the Tibetan Plateau since the Cenozoic strongly changed the Asian topography and greatly impacted not only the regional but also the global climate. Being sensitive to past climate changes, fossil plants are proven pivotal bio-indicators that can infer the paleoclimate and paleoelevation of different Tibetan Plateau parts. However, the timing and mechanisms of the uplift in the northeastern Tibetan Plateau remain debated due to limited evidence from plant fossils and inconsistent results. In this investigation, <em>Pueraria</em> leaflet and pod fossils collected from the Miocene Upper Youshashan Formation of the Wulan Basin, northeastern Tibetan Plateau, are reported. The leaflet fossils are assigned as a new species: <em>Pueraria qinghaiensis</em> Zhen-Dong Cao et San-Ping Xie sp. nov., while <em>P. montana</em> is recognized as its nearest living relative; the pod fossils are assigned as <em>Pueraria</em> sp. The leaflet margins of <em>P. qinghaiensis</em> and other fossils found in the same layer indicate that <em>Pueraria</em> from the Wulan Basin likely lived in open habitats and sprawled at the waterside. Moreover, the climate of the basin apparently was warm and humid in the Middle Miocene, and the elevation was about 723–2398 m based on the ecological niche of <em>Pueraria</em>. The occurrence of these new <em>Pueraria</em> fossils from the Wulan Basin supports the view that the elevation of the northeastern Tibetan Plateau did not attain its present elevation during the Middle Miocene. Subsequently, the plateau's uplift caused a series of environmental transformations, including increased elevation, reduced temperature and precipitation, and the intensification of Asian monsoons, which altogether led to the regional disappearance of the <em>Pueraria</em> population in the Wulan Basin.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 2","pages":"Pages 413-430"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143868998","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":"Depositional age and provenance of Triassic sedimentary succession from Northwestern México: Evidence from petrography and detrital zircon U–Pb geochronology","authors":"Erik Ramirez-Montoya ,&nbsp;Jayagopal Madhavaraju ,&nbsp;Rogelio Monreal ,&nbsp;Luigi Solari","doi":"10.1016/j.jop.2025.01.001","DOIUrl":"10.1016/j.jop.2025.01.001","url":null,"abstract":"<div><div>The sedimentary succession of the El Antimonio Group, which unconformably overlies the Permian (Guadalupian) Monos Formation, is well exposed in the Sierra del Álamo section, southwest of Caborca, Sonora, México. Here, this section is composed of the Triassic Santa Eduwiges (renamed from the previous Antimonio Formation) and Río Asunción and the Lower Jurassic Sierra de Santa Rosa formations. This study focuses on the provenance and geochronology of the Triassic formations. The sandstone of Santa Eduwiges and Rio Asuncion formations are classified from litharenite to arkose. On the QtFL diagram, sandstone samples plot in the orogenic, transitional continental and undissected arc fields. In contrast, on the QmFLt diagram, the samples are mainly concentrated in the mixed, transitional continental and quartzose recycled fields. Main zircon populations identified in this study are Triassic, Permian and Proterozoic. Proterozoic zircon grains are grouped into ∼1.8, 1.7, 1.6, 1.4 and 1.1 Ga populations whose primary sources are the crustal basement rocks of the Mojave Yavapai and Mazatzal provinces of southwestern North America, and Mesoproterozoic granitic plutons that intrude them. Permo-Triassic zircon grains may be sourced in magmatic arc rocks of this age that in southwestern North America is well presented in northwestern Sonora. The detrital zircon dated allows us to constrain maximum depositional ages for the Triassic Santa Eduwiges Formation of the El Antimonio Group: the youngest zircon grains from lowermost part (Sequence I) yielded an age of 252.64±1.98 Ma; zircon grains from its middle part (Sequence IV) yielded an age of 244.63±3.04 Ma and zircon grains from Sequence VI of the upper part of this unit yielded an age of 229.33±1.72 Ma. The El Antimonio Group was deposited in a forearc basin located south as a product of the Permo-Triassic continental magmatic arc that contributed much of the detritus to the early Triassic basin. During later stages of sedimentation in the Triassic basin, detritus was mostly sourced from the Proterozoic basement rocks.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 2","pages":"Pages 370-390"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143868996","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":"Astronomical forces as a potential cause for the end-guadalupian biotic crisis: A case study from central Alborz, Iran","authors":"Forough Abasaghi ,&nbsp;Rui Zhang ,&nbsp;Qing-Yong Luo ,&nbsp;Ren Wei","doi":"10.1016/j.jop.2024.12.007","DOIUrl":"10.1016/j.jop.2024.12.007","url":null,"abstract":"<div><div>The Middle Permian extinction event is considered one of the most devastating events of all Phanerozoic biotic crises, yet it is not fully understood and has attracted a lot of controversial comments. This event is found at the end of the Capitanian carbonate strata in the Ruteh Formation (late Wordian–Capitanian) at the Alborz Mountains in Iran. It is characterized by the decimation of marine organisms, particularly calcareous algae and microproblematic fossils. The current study attempts to interpret the cause of this crisis in the framework of astronomically-forced climatic changes. Based on cyclostratigraphy analysis, the evidence of the Milankovitch cycles, including long eccentricity, short eccentricity, obliquity, and precession are recorded in the Ruteh Formation succession. The establishment of a floating astronomical time scale using the long eccentricity cycles led to an estimation of a duration of 1.6 and 2.43 million years for the Wordian and Capitanian stages, respectively. Integrated facies studies and a sedimentary noise model indicate that the Ruteh Formation is composed of three ∼1.2 Myr sequences, corresponding to third-order sequences, and ten 405-kyr sequences, corresponding to fourth-to fifth-order sequences. The boundaries of the ∼1.2 Myr sequences indicate regression in sea level and low sedimentation rate. Considering the paleogeographic situation of the Alborz Mountains, the sedimentation of the Ruteh Formation in the Middle Permian was affected by the Inter-Tropical Convergence Zone and interactions between the ocean and atmosphere during the Pangea assemblage, leading to an increase in temperature. With the sum of these observations, we conclude that factors such as high temperature and a decrease in sedimentation rate created unfavorable conditions for the mentioned biota at the end of the Capitanian.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 2","pages":"Pages 603-628"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143869267","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":"Origin and depositional environments of mounded, banded and bedded dolostones in the clastic deposits of the Paleoproterozoic Chuanlinggou Formation in Beijing, North China","authors":"Jin-Yi Wang,&nbsp;Zhen-Kui Jin,&nbsp;Hao Cheng,&nbsp;Ke-Bei Hua,&nbsp;Hao-Xuan Ran","doi":"10.1016/j.jop.2024.11.005","DOIUrl":"10.1016/j.jop.2024.11.005","url":null,"abstract":"<div><div>Various studies have indicated that microbes were involved in the precipitation of dolostones in the Proterozoic. The identification of ancient microbial dolostones remains challenging due to the rare preservation of microbe fossils. In this study, we found ancient microbial dolostones in Paleoproterozoic Chuanlinggou Formation in Beijing, North China, employing thin-section observations, trace and rare earth elements as well as carbon and oxygen isotope analyses to reveal the origin. The paleoenvironment has also been reconstructed. The results indicate that dolostones found in the Chuanlinggou Formation are formed through primary dolomite precipitation induced by cyanobacterial activity. These dolomitized geobodies exhibit various morphologies of mounded, banded and bedded, and all dolostones are microcrystalline textures. The geochemical characteristics of these dolostones show a relatively low δ¹⁸O value (average = −7.34‰), Fe(II) enrichment, Ce anomaly and comparable patterns of REY. The specific geomorphology (mounded, banded and bedded) and mottled structures of the dolostones indicate that they are formed through in-situ dolomite precipitation induced by cyanobacterial activity. The high Fe(II) content suggests a reducing environment, whereas the Ce anomaly indicates anoxic conditions within the water body. The REY patterns provide evidence for the microbial origin of the dolostones. These dolostones were formed in clastic off-shore shelf environments. The seawater was warm, normal in salinity, and the sea floor was slightly agitated to quiet and reducing. The geomorphology of the dolomitized geobodies changes from mounded to banded and bedded in correlation with depth increase and hydrodynamic energy decrease. This study may provide another type of environments for microbial dolostones and the geochemical characteristics of these dolostones may serve as a valuable reference for identifying similar ancient microbial dolostones.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 2","pages":"Pages 629-650"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143869268","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 role of algal reproduction in phylloid algal buildups: a case study in Pennsylvanian phylloid algae in southern Guizhou, China","authors":"Jun-Jie Wang ,&nbsp;En-Pu Gong ,&nbsp;Yong-Li Zhang ,&nbsp;Wen-Tao Huang ,&nbsp;Xiao Li ,&nbsp;Li-Fu Wang ,&nbsp;Guan-Ming Lai ,&nbsp;De-Peng Li","doi":"10.1016/j.jop.2025.02.002","DOIUrl":"10.1016/j.jop.2025.02.002","url":null,"abstract":"<div><div>The well-preserved reproductive morphology of <em>Eugonophyllum</em> within Pennsylvanian algal deposits in Guizhou Province, South China, provides a unique opportunity to study phylloid algal ecology and its role in carbonate buildups. Vegetative reproduction, characterized by the branching growth of algal segments followed by lateral budding in young thalli, appears to be the primary mechanism for maintaining and continuously increasing the population in the community. This method provides a dense, stable framework and bioclastic sediments for the development of lateral growth. Sexual reproduction occurs among mature thalli (comprising approximately 5%–10% of the population) and is characterized by synchronous gamete release. The synchronous spawning periodically increases the population and controls reef growth by the superposition of alternating generations. The combined effects of intrinsic factors of phylloid algae (rapid growth and reproductive strategy) and extrinsic factors (nutrient availability, ocean chemistry, seawater temperature) contributed to the dominance of phylloid algae in reef ecosystems in tropical-subtropical regions during the Pennsylvanian. Detailed evidence of <em>Eugonophyllum</em> growth and reproduction reveals the widespread distribution and high productivity of phylloid algae, opening new insights into global algal reef ecosystem blooms.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 2","pages":"Pages 664-678"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143869270","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":"Early Pleistocene vertebrate tracks impressed on Oligocene beds from the southernmost Iberian Peninsula: Palaeogeographic implications","authors":"Eduardo Mayoral ,&nbsp;Antonio Rodríguez Ramírez ,&nbsp;Jérémy Duveau ,&nbsp;Ricardo Díaz-Delgado ,&nbsp;Juan Antonio Morales ,&nbsp;Eloísa Bernáldez Sánchez ,&nbsp;Esteban García-Viñas ,&nbsp;Ana Santos ,&nbsp;Mili Jiménez Melero ,&nbsp;Milagros Alzaga ,&nbsp;Ignacio Díaz-Martínez","doi":"10.1016/j.jop.2025.01.004","DOIUrl":"10.1016/j.jop.2025.01.004","url":null,"abstract":"<div><div>The southern of the Iberian Peninsula preserves a diverse ichnological record of vertebrates from the late Neogene–Quaternary. While the ages of several tracksites, such as those from the Miocene–Pliocene transition and the middle-late Pleistocene, are well-established, others remain undated or have unknown ages. This paper reports the discovery of the southernmost tracksite in the Iberian Peninsula and continental Europe on the Island of Tarifa (Cádiz). The tracksite contains over 600 vertebrate footprints from the early Pleistocene that are grouped in four morphotypes. Morphotypes 1, 2 and 3 (M1, M2 and M3) are predominantly didactyl-shaped, rounded to ovoid and elongated, and associated with tracks left by artiodactyls. Morphotype 4 (M4), suboval to subcircular in outline, is the largest and is probably related to the imprint left by proboscideans.</div><div>We also document the progressive transition from morphotype 2 with isolated, rounded footprints to morphotype 3 with elongated tracks formed by overlapping two tracks of the same animal which is observed. The consistency of the substrate, together with the trackmaker limb dynamics, conditioned the final morphology of the tracks, which were produced in a very soft clay-rich substrate of late Oligocene, that was folded and tilted in the latest Pliocene. This relief configuration gave rise to a narrow, partially or totally flooded corridor through which the trackmaker animals passed continuously, simultaneously, and in opposite ways. This discovery from the southernmost tip of continental Europe is the first one from the early Pleistocene in the Iberian Peninsula and a rare example from the Mediterranean region.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 2","pages":"Pages 315-333"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143869228","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":"Two ribbon-like macrofossils in contrasting preservational styles from the Ediacaran–Cambrian interval","authors":"Yu-Lan Li ,&nbsp;Giovanni Mussini ,&nbsp;Li-Jun Zhang ,&nbsp;Si-Cun Song ,&nbsp;Ming Li ,&nbsp;Ling Zhong ,&nbsp;Feng Tang","doi":"10.1016/j.jop.2025.03.002","DOIUrl":"10.1016/j.jop.2025.03.002","url":null,"abstract":"<div><div>The fossil record of the latest Ediacaran and earliest Cambrian comprises diverse tubular and ribbon-like macrofossils of uncertain affinities, some of which could record early metazoans and macroalgae. This study compares two ribbon-like macrofossils typical of Ediacaran–Cambrian intervals, investigating their morphology, potential affinities, and biostratigraphic significance: <em>Rugosusivitta</em>, preserved as essentially two-dimensional carbonaceous compressions, and <em>Harlaniella,</em> preserved as casts and molds. It is shown that the recently described <em>Rugosusivitta orthogonia</em> Tang et al., 2021 resembles the tube-like <em>Harlaniella ingriana</em> in its morphology, characterized by a combination of transverse ridges and longitudinal stripes separated into distinct parts of an elongate body. This combination of features challenges algal or protistan affinities, leaving open the possibility of metazoan origins. Both <em>Rugosusivitta</em> and <em>Harlaniella</em> likely represent body fossils rather than ichnofossils consistent with their preservation as either carbonaceous compressions or sediment-infilled tubes, respectively. By reconstructing the global distribution of <em>Rugosusivitta</em> and <em>Harlaniella</em> in different taphonomic windows, we suggest that these fossils record a coherent morphotype spanning the Ediacaran–Cambrian boundary.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 2","pages":"Pages 651-663"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143869269","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":"Palaeogeomorphological control on the depositional architecture of lacustrine gravity-flow deposits in a depression lacustrine basin: a case study of the Triassic Yanchang Formation, southern Ordos Basin, China","authors":"Ming-Cheng Liu ,&nbsp;Sheng-He Wu ,&nbsp;Da-Li Yue ,&nbsp;Zhen-Hua Xu ,&nbsp;Xiao-Long Wan ,&nbsp;Hong-Li Wu ,&nbsp;Zhao-Hui Chen ,&nbsp;Zhen Li","doi":"10.1016/j.jop.2025.01.003","DOIUrl":"10.1016/j.jop.2025.01.003","url":null,"abstract":"<div><div>Lacustrine gravity-flow deposits have enormous hydrocarbon potential. However, their depositional architecture has long been considered very complicated and is controlled by various factors, making petroleum exploration and development highly challenging. The influence of palaeogeomorphology on the extent and formation mechanisms of lacustrine gravity-flow deposits remains poorly understood. This study uses 3D seismic data, well-log data, and core data to characterize the palaeogeomorphology and depositional architecture of the lacustrine gravity-flow deposit of the Yanchang Formation in the Ordos Basin, while analyzing the influence of palaeogeomorphology on the architecture, distribution, and evolution of lacustrine gravity-flow deposit systems. The results showed that three palaeogeomorphologic units—shelf, slope, and basin floor—developed in the basin. Gravity-flow deposits can be further divided into channel and lobe systems. Gravity-flow channel systems have developed in the upper slope area, which include three types of architectural elements: confined channels, unconfined channels, and levee-overbank. As the transport distance of gravity flow increases, the erosion ability of gravity flow weakens, resulting in the terrain formed by gravity flow erosion gradually weakening the constraint on sediment transport. Consequently, gravity-driven flow pathways shift from linear, confined channels to curved, unconfined channels, finally leading to the development of numerous distributary channels. In the lower slope area, gravity flow sediments distribute rapidly and accumulate to form lobes after encountering slope breaks, due to the decrease of dynamics, including three types of architectural elements: distributary channels, lobe axis and lobe fringe. These lobes are tongue-shaped and fan-shaped on the plane. A series of lobes are superimposed and form a lobe complex set. These lobe complex sets are distributed in a branch-like manner. There are many branch-shaped low-bend amplitude channels inside the lobe complex set. Palaeogeomorphology plays an important role in controlling the spatial distribution of depositional architecture. As the slope gradient increases, the influence of slope break on sediment gravity flow weakens, leading to a delay of the sediment gravity flow slumping to the basin bottom. Additionally, the extension length of the channel system on the slope increases. Furthermore, the extension length of the lobes toward the center of the basin also increases. This work improves the fundamental understanding of the depositional architecture of lacustrine gravity-flow deposits and may help enhance sand prediction for the same type deposit reservoirs.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"14 2","pages":"Pages 476-500"},"PeriodicalIF":0.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143869314","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}