Pub Date : 2024-10-01DOI: 10.1016/j.jop.2024.08.006
Wei Yu , Feng Wang , Jing-Chun Tian , Jiao Wang , Benjamin Kneller , Tian Yang , Wei-Zhen Chen
Shales in deep lake basins have become the main focus of continental shale oil and gas exploration. In order to highlight the sedimentary dynamics of mud deposition in deep lake basins, a combination of core observation, thin section examination, X-ray diffraction, and QEMSCAN (quantitative evaluation of minerals by scanning electron microscopy) was used to analyze the depositional characteristics of mudrocks in the Chang-7 Member from the Yanchang Formation (Upper Triassic) in Ordos Basin, and to establish a depositional model for mud accumulation in deep lake basins. This study recognizes four mudrock lithofacies in the Chang-7 Member: (1) the laminated silt-bearing mudstone, which generally develops a binary composition of “silt–clay” or a ternary composition of “silt–clay–organic matter”; (2) the graded mudstone, mainly composed of dark gray and gray-black mudstone sandwiched by silt-bearing mudstone; (3) the massive mudstone, internally showing a uniform distribution of quartz, clay, and carbonate minerals, with also a small amount of organic detritus; and (4) the laminated shale, which is generally composed of clay laminae, and organic laminae of the former two. Sediment supply, topographic slope, and flood intensity combine to control the evolution of gravity flows and the transport and deposition of the mudrock in the Chang-7 Member. The influence of orogeny provides terrain gradient, water depth, abundant sediments at source areas, and triggering mechanism for the formation of gravity flows. Floods triggered by wetting events provide the impetus for sediment transport. Mud deposition in the Chang-7 Member was mainly related to the transport and sedimentation of mud by hyperpycnal flows and rapid sedimentation by buoyant plume flocculation. A comprehensive evolutionary model for shale accumulation in the deep lake basin is established by integrating various triggering mechanisms and mud transport sedimentary processes.
{"title":"Sedimentary dynamics and depositional model for mud accumulation in deep lake basins: A case study in the Upper Triassic Chang-7 Member, Ordos Basin, northern China","authors":"Wei Yu , Feng Wang , Jing-Chun Tian , Jiao Wang , Benjamin Kneller , Tian Yang , Wei-Zhen Chen","doi":"10.1016/j.jop.2024.08.006","DOIUrl":"10.1016/j.jop.2024.08.006","url":null,"abstract":"<div><div>Shales in deep lake basins have become the main focus of continental shale oil and gas exploration. In order to highlight the sedimentary dynamics of mud deposition in deep lake basins, a combination of core observation, thin section examination, X-ray diffraction, and QEMSCAN (quantitative evaluation of minerals by scanning electron microscopy) was used to analyze the depositional characteristics of mudrocks in the Chang-7 Member from the Yanchang Formation (Upper Triassic) in Ordos Basin, and to establish a depositional model for mud accumulation in deep lake basins. This study recognizes four mudrock lithofacies in the Chang-7 Member: (1) the laminated silt-bearing mudstone, which generally develops a binary composition of “silt–clay” or a ternary composition of “silt–clay–organic matter”; (2) the graded mudstone, mainly composed of dark gray and gray-black mudstone sandwiched by silt-bearing mudstone; (3) the massive mudstone, internally showing a uniform distribution of quartz, clay, and carbonate minerals, with also a small amount of organic detritus; and (4) the laminated shale, which is generally composed of clay laminae, and organic laminae of the former two. Sediment supply, topographic slope, and flood intensity combine to control the evolution of gravity flows and the transport and deposition of the mudrock in the Chang-7 Member. The influence of orogeny provides terrain gradient, water depth, abundant sediments at source areas, and triggering mechanism for the formation of gravity flows. Floods triggered by wetting events provide the impetus for sediment transport. Mud deposition in the Chang-7 Member was mainly related to the transport and sedimentation of mud by hyperpycnal flows and rapid sedimentation by buoyant plume flocculation. A comprehensive evolutionary model for shale accumulation in the deep lake basin is established by integrating various triggering mechanisms and mud transport sedimentary processes.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 775-792"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195271","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}
Pub Date : 2024-10-01DOI: 10.1016/j.jop.2024.07.004
Hua-Shan Zhang , Ming-Yue Dai , Yong-An Qi , Lan-Lan Han , Zhong-Lei Yin , Song-Hua Chen , Liang-Biao Lin
Girvanella is one of the common genera of cyanobacteria that plays a monumental role in the evolution of life on Earth and the formation of microbialites. Based on a detailed search in the literature of Girvanella fossils, we have compiled a global database of Girvanella fossils and revealed the evolution of Girvanella fossils throughout the Phanerozoic. Four species, Girvanella kasakiensis, Girvanella problematica, Girvanella wetheredii, and Girvanella staminea, are recognized and described. These data show that Girvanella fossils have well-defined temporal distribution during the Paleozoic Era, have a significant temporal gap in the Mesozoic Era, and have only been recorded sporadically in the Cenozoic Era. They were relatively abundant during the Cambrian Epoch 2–Early Ordovician, Late Ordovician, Late Devonian–Mississippian, and tended to lesser degrees during the Silurian–Early Devonian, Lopingian Epoch–Middle Jurassic, and Cretaceous–Present day. Furthermore, the evolution of the abundance and diversity of Girvanella fossils was fundamentally consistent and showed episodical declining during the Phanerozoic. To further explore these relationships, we thoroughly compared them with environmental factors such as seawater carbonate saturation state, Ca2+ concentration, pH values, and atmospheric partial pressure of carbon dioxide (pCO2). This study indicates that seawater carbonate saturation state and Ca2+ concentration are major controls on secular patterns of the abundance and diversity of Girvanella fossils, together with the secondary factors of pH values and pCO2. Considering the long history of Girvanella fossils, their abundance and diversity offer the potential to assist the interpretation of the long-term evolution of marine and atmosphere components during the Phanerozoic.
是蓝藻的常见属种之一,在地球生命进化和微生物岩的形成过程中发挥着不朽的作用。在对化石文献进行详细检索的基础上,我们编制了一个全球化石数据库,并揭示了化石在整个新生代的演化过程。确认并描述了、、和四个物种。这些数据表明,化石在古生代有明确的时间分布,在中生代有明显的时间空白,在新生代仅有零星记录。它们在寒武纪第二世-奥陶纪早期、奥陶纪晚期、泥盆纪晚期-密西西比期数量相对较多,在志留纪-泥盆纪早期、罗平纪-侏罗纪中期和白垩纪-现今数量较少。此外,化石的丰度和多样性的演变基本一致,在新生代期间呈偶发性下降。为了进一步探讨这些关系,我们将其与海水碳酸盐饱和状态、钙浓度、pH 值和大气二氧化碳分压等环境因素进行了深入比较。这项研究表明,海水碳酸盐饱和状态和钙的浓度是控制化石丰度和多样性的主要因素,pH 值和 CO 是次要因素。考虑到化石的悠久历史,它们的丰度和多样性有可能有助于解释新生代期间海洋和大气成分的长期演变。
{"title":"Girvanella fossils from the Phanerozoic: Distribution, evolution and controlling factors","authors":"Hua-Shan Zhang , Ming-Yue Dai , Yong-An Qi , Lan-Lan Han , Zhong-Lei Yin , Song-Hua Chen , Liang-Biao Lin","doi":"10.1016/j.jop.2024.07.004","DOIUrl":"10.1016/j.jop.2024.07.004","url":null,"abstract":"<div><div><em>Girvanella</em> is one of the common genera of cyanobacteria that plays a monumental role in the evolution of life on Earth and the formation of microbialites. Based on a detailed search in the literature of <em>Girvanella</em> fossils, we have compiled a global database of <em>Girvanella</em> fossils and revealed the evolution of <em>Girvanella</em> fossils throughout the Phanerozoic. Four species, <em>Girvanella kasakiensis</em>, <em>Girvanella problematica</em>, <em>Girvanella wetheredii</em>, and <em>Girvanella staminea</em>, are recognized and described. These data show that <em>Girvanella</em> fossils have well-defined temporal distribution during the Paleozoic Era, have a significant temporal gap in the Mesozoic Era, and have only been recorded sporadically in the Cenozoic Era. They were relatively abundant during the Cambrian Epoch 2–Early Ordovician, Late Ordovician, Late Devonian–Mississippian, and tended to lesser degrees during the Silurian–Early Devonian, Lopingian Epoch–Middle Jurassic, and Cretaceous–Present day. Furthermore, the evolution of the abundance and diversity of <em>Girvanella</em> fossils was fundamentally consistent and showed episodical declining during the Phanerozoic. To further explore these relationships, we thoroughly compared them with environmental factors such as seawater carbonate saturation state, Ca<sup>2+</sup> concentration, pH values, and atmospheric partial pressure of carbon dioxide (<em>p</em>CO<sub>2</sub>). This study indicates that seawater carbonate saturation state and Ca<sup>2+</sup> concentration are major controls on secular patterns of the abundance and diversity of <em>Girvanella</em> fossils, together with the secondary factors of pH values and <em>p</em>CO<sub>2</sub>. Considering the long history of <em>Girvanella</em> fossils, their abundance and diversity offer the potential to assist the interpretation of the long-term evolution of marine and atmosphere components during the Phanerozoic.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 924-938"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195275","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}
Pub Date : 2024-10-01DOI: 10.1016/j.jop.2024.08.004
Carlos Zavala , Hua-Qing Liu , Xiang-Bo Li , Valentin Trobbiani , Yang Li , Mariano Arcuri , Agustin Zorzano
<div><div>Sequence stratigraphic concepts and methods provide novel tools for performing stratigraphic analysis, allowing us to improve our understanding of depositional models and basin evolution. Main controls and depositional elements (e.g., surfaces, systems tracts, parasequences, etc.) recognized in conventional sequence stratigraphy are designed for marine-related systems. In contrast, the sequence stratigraphy of lacustrine successions is much more complex and poorly understood, because it is not driven by sea-level changes, but by a complex interaction between tectonics and high-frequency climatic cycles. The comprehensive analysis of the water balance of lacustrine systems allows the recognition of three types of lake conditions: Underfilled, balanced-fill and overfilled lakes. Understanding the lake conditions in ancient successions is fundamental for unraveling lacustrine sequence stratigraphy, since these conditions effectively control water salinity, internal stacking pattern and the characteristics of systems tracts. Underfilled lakes are hydrologically closed lakes, and consequently, the lake-level can highly fluctuate, driven by high-frequency wet-dry climatic cycles. During wet periods, rivers supply water and sediments, resulting in fining-and thinning-upward elementary depositional sequences (EDS's) accumulated during the transgressive systems tract (TST). In contrast, dry periods are characterized by a relative lake-level fall with the subaerial exposure of lake margin areas during the regressive systems tract (RST). Lake water salinity can fluctuate from brackish to hypersaline. Balanced-fill lakes are partially closed lakes, and consequently, they have characteristics of both underfilled and overfilled lakes. During the TST, the lake is in underfilled condition, and consequently, the introduction of water and sediment will accumulate a fining-upward interval until reaching the spill point during the maximum flooding. The RST is accumulated under an overfilled lake condition, with coarsening-upward progradational littoral deltas and related subaqueous delta deposits. Lake water salinity fluctuates from brackish to freshwater. Overfilled lakes are hydrologically open lakes. Most deposits accumulate during the RST, forming coarsening-upward progradational littoral deposits, with associated subaqueous deltas. All overfilled lakes are freshwater lakes. Subsidence is crucial for allowing the long-term preservation of lacustrine deposits. Lakes can temporarily store water and sediments in areas that lack subsidence, but these deposits will not be preserved in the stratigraphic record. Consequently, two types of lakes are recognized: 1) subsiding lakes, which have permanent accommodation space and 2) hanging lakes, having temporary accommodation space. Although they cannot permanently store sediments, hanging lakes are fundamental for lacustrine sequence stratigraphy, since they can flood subsiding lakes with the near-instantaneous
{"title":"High-frequency lacustrine sequence stratigraphy of clastic lakes: lessons from ancient successions","authors":"Carlos Zavala , Hua-Qing Liu , Xiang-Bo Li , Valentin Trobbiani , Yang Li , Mariano Arcuri , Agustin Zorzano","doi":"10.1016/j.jop.2024.08.004","DOIUrl":"10.1016/j.jop.2024.08.004","url":null,"abstract":"<div><div>Sequence stratigraphic concepts and methods provide novel tools for performing stratigraphic analysis, allowing us to improve our understanding of depositional models and basin evolution. Main controls and depositional elements (e.g., surfaces, systems tracts, parasequences, etc.) recognized in conventional sequence stratigraphy are designed for marine-related systems. In contrast, the sequence stratigraphy of lacustrine successions is much more complex and poorly understood, because it is not driven by sea-level changes, but by a complex interaction between tectonics and high-frequency climatic cycles. The comprehensive analysis of the water balance of lacustrine systems allows the recognition of three types of lake conditions: Underfilled, balanced-fill and overfilled lakes. Understanding the lake conditions in ancient successions is fundamental for unraveling lacustrine sequence stratigraphy, since these conditions effectively control water salinity, internal stacking pattern and the characteristics of systems tracts. Underfilled lakes are hydrologically closed lakes, and consequently, the lake-level can highly fluctuate, driven by high-frequency wet-dry climatic cycles. During wet periods, rivers supply water and sediments, resulting in fining-and thinning-upward elementary depositional sequences (EDS's) accumulated during the transgressive systems tract (TST). In contrast, dry periods are characterized by a relative lake-level fall with the subaerial exposure of lake margin areas during the regressive systems tract (RST). Lake water salinity can fluctuate from brackish to hypersaline. Balanced-fill lakes are partially closed lakes, and consequently, they have characteristics of both underfilled and overfilled lakes. During the TST, the lake is in underfilled condition, and consequently, the introduction of water and sediment will accumulate a fining-upward interval until reaching the spill point during the maximum flooding. The RST is accumulated under an overfilled lake condition, with coarsening-upward progradational littoral deltas and related subaqueous delta deposits. Lake water salinity fluctuates from brackish to freshwater. Overfilled lakes are hydrologically open lakes. Most deposits accumulate during the RST, forming coarsening-upward progradational littoral deposits, with associated subaqueous deltas. All overfilled lakes are freshwater lakes. Subsidence is crucial for allowing the long-term preservation of lacustrine deposits. Lakes can temporarily store water and sediments in areas that lack subsidence, but these deposits will not be preserved in the stratigraphic record. Consequently, two types of lakes are recognized: 1) subsiding lakes, which have permanent accommodation space and 2) hanging lakes, having temporary accommodation space. Although they cannot permanently store sediments, hanging lakes are fundamental for lacustrine sequence stratigraphy, since they can flood subsiding lakes with the near-instantaneous ","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 621-645"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263760","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}
Pub Date : 2024-10-01DOI: 10.1016/j.jop.2024.06.003
Anisotropy of Magnetic Susceptibility (AMS) data from a ∼27.8 m thick soft sedimentary mud sequence (∼10.5–3.25 k yrs) from the Spituk Palaeolake Sequence (SPSS) of Holocene age, located in the northern bank of the Indus River in the Leh-Ladakh Himalaya, show effects of tectonic versus climate dynamics responsible for the Himalayan sedimentation. The sedimentary sequence, consisting of alternating of aeolian sand and glacio-fluvial mud flow deposits, has been subdivided into an older Last Glacier Phase I (LGP 1) and a younger Last Glacier Phase II (LGP 2), where the termination of each phase is marked by the occurrence of gravel beds of thickness ≤1 m, which were deposited due to glacial melting. The present AMS data along with previously published information on sedimentology confirm that the mudflow deposits of the LGP 1 and LGP 2 phases were deposited in a lacustrine environment under glacio-fluvial conditions. However, a weak fluvial flow towards NW and NE could have existed for the LGP 1 and LGP 2, respectively. The glacial beds terminating LGP 1 and LGP 2 appear to have formed by climatic warming and tectonic activity, respectively. Hence, the Holocene Himalayan sedimentation was influenced by both climatic and tectonic activities. However, the thickness of the gravel bed (∼0.8 m) terminating LGP 2 occupies only ∼ 2.8 vol % of the total studied thickness ∼28 m, of the SPSS in the present study, which indicated a lesser control of tectonism in the growth of the Himalaya in and around the study area.
{"title":"A combined tectono-climatic control on Holocene sedimentation in Ladakh Himalaya, India: Clues from Anisotropy of Magnetic Susceptibility (AMS) of lake sediments","authors":"","doi":"10.1016/j.jop.2024.06.003","DOIUrl":"10.1016/j.jop.2024.06.003","url":null,"abstract":"<div><div>Anisotropy of Magnetic Susceptibility (AMS) data from a ∼27.8 m thick soft sedimentary mud sequence (∼10.5–3.25 k yrs) from the Spituk Palaeolake Sequence (SPSS) of Holocene age, located in the northern bank of the Indus River in the Leh-Ladakh Himalaya, show effects of tectonic versus climate dynamics responsible for the Himalayan sedimentation. The sedimentary sequence, consisting of alternating of aeolian sand and glacio-fluvial mud flow deposits, has been subdivided into an older Last Glacier Phase I (LGP 1) and a younger Last Glacier Phase II (LGP 2), where the termination of each phase is marked by the occurrence of gravel beds of thickness ≤1 m, which were deposited due to glacial melting. The present AMS data along with previously published information on sedimentology confirm that the mudflow deposits of the LGP 1 and LGP 2 phases were deposited in a lacustrine environment under glacio-fluvial conditions. However, a weak fluvial flow towards NW and NE could have existed for the LGP 1 and LGP 2, respectively. The glacial beds terminating LGP 1 and LGP 2 appear to have formed by climatic warming and tectonic activity, respectively. Hence, the Holocene Himalayan sedimentation was influenced by both climatic and tectonic activities. However, the thickness of the gravel bed (∼0.8 m) terminating LGP 2 occupies only ∼ 2.8 vol % of the total studied thickness ∼28 m, of the SPSS in the present study, which indicated a lesser control of tectonism in the growth of the Himalaya in and around the study area.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 738-753"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141508900","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}
Pub Date : 2024-10-01DOI: 10.1016/j.jop.2024.06.004
<div><div>Field-based sedimentology, state of the art facies analysis and sequence stratigraphic framework analysis have revealed the controls of local and global tectonics, basin-marginal slope, climate and changes in relative sea level (RSL) over the sedimentation pattern and evolution of a Neoproterozoic Kerur Formation within the Badami Group of Kaladgi Supergroup in India. The entire succession shows three major cycles of deposition. Facies study and fluvial architectural elemental analysis suggest considerable variations in depositional environments as well as palaeogeography. A transition from basin-margin alluvial cone deposits to braided system, initially with fluctuating ephemeral flows then to a steadier semi-perennial nature, is discernible within the 1<sup>st</sup> cycle, in response to decreasing depositional slope with rising water table. The initial alluvial cone and braided ephemeral streams of high slope areas is designated as a product of low accommodation systems tract (LAST), while the semi-perennial system with steadier flows, representing the axial river of the initial rift valley, appears to be a product of high – accommodation systems tract (HAST). The 2<sup>nd</sup> cycle begins with a perennial and steady braided river system and grades upward to a shallow marine succession, comprising wave-dominated, well-sorted sandstone, with a granular transgressive lag at the base. Thus, the bottommost fluvial interval of the 2<sup>nd</sup> cycle constitutes the lowstand systems tract (LST). The marine succession represents deposits of outer shelf offshore to foreshore-beach settings and is composed of an initially deepening and fining upward transgressive systems tract (TST), followed by a coarsening and shallowing upward highstand systems tract (HST) with a maximum marine flooding surface (MFS) in between, demarcated by a shale-rich condensed zone. The 3<sup>rd</sup> cycle, with its prograding alluvial fan and aggrading braided fluvial deposits and restricted occurrence, represents only the low accommodation systems tract (LAST) with a subaerial unconformity at the base. The basin evidently initiated in the western sector, followed by its eastward expansion during the first major rejuvenation of the basin margin faults, after the deposition of the 1<sup>st</sup> cycle. After the basin-wide deposition of the 2<sup>nd</sup> cycle, restricted development of the 3<sup>rd</sup> cycle took place in the western sector only, following the second major rejuvenation of the fault system. The proposed sedimentological model, supported by established geochronological constraints, suggests that the sedimentation in the 1<sup>st</sup> cycle begins with scree cones, alluvial fans and braided ephemeral channel networks, originated from faulted basin margins within a riftogenic setting possibly related to the global-scale extensional tectonics of Rodinia breakup. After the expansion of the basin, the marine inundation has been correlated to the tr
{"title":"Evolution of Neoproterozoic siliciclastic Kerur Formation in the light of sequence stratigraphic framework: Badami Basin, Karnataka, India","authors":"","doi":"10.1016/j.jop.2024.06.004","DOIUrl":"10.1016/j.jop.2024.06.004","url":null,"abstract":"<div><div>Field-based sedimentology, state of the art facies analysis and sequence stratigraphic framework analysis have revealed the controls of local and global tectonics, basin-marginal slope, climate and changes in relative sea level (RSL) over the sedimentation pattern and evolution of a Neoproterozoic Kerur Formation within the Badami Group of Kaladgi Supergroup in India. The entire succession shows three major cycles of deposition. Facies study and fluvial architectural elemental analysis suggest considerable variations in depositional environments as well as palaeogeography. A transition from basin-margin alluvial cone deposits to braided system, initially with fluctuating ephemeral flows then to a steadier semi-perennial nature, is discernible within the 1<sup>st</sup> cycle, in response to decreasing depositional slope with rising water table. The initial alluvial cone and braided ephemeral streams of high slope areas is designated as a product of low accommodation systems tract (LAST), while the semi-perennial system with steadier flows, representing the axial river of the initial rift valley, appears to be a product of high – accommodation systems tract (HAST). The 2<sup>nd</sup> cycle begins with a perennial and steady braided river system and grades upward to a shallow marine succession, comprising wave-dominated, well-sorted sandstone, with a granular transgressive lag at the base. Thus, the bottommost fluvial interval of the 2<sup>nd</sup> cycle constitutes the lowstand systems tract (LST). The marine succession represents deposits of outer shelf offshore to foreshore-beach settings and is composed of an initially deepening and fining upward transgressive systems tract (TST), followed by a coarsening and shallowing upward highstand systems tract (HST) with a maximum marine flooding surface (MFS) in between, demarcated by a shale-rich condensed zone. The 3<sup>rd</sup> cycle, with its prograding alluvial fan and aggrading braided fluvial deposits and restricted occurrence, represents only the low accommodation systems tract (LAST) with a subaerial unconformity at the base. The basin evidently initiated in the western sector, followed by its eastward expansion during the first major rejuvenation of the basin margin faults, after the deposition of the 1<sup>st</sup> cycle. After the basin-wide deposition of the 2<sup>nd</sup> cycle, restricted development of the 3<sup>rd</sup> cycle took place in the western sector only, following the second major rejuvenation of the fault system. The proposed sedimentological model, supported by established geochronological constraints, suggests that the sedimentation in the 1<sup>st</sup> cycle begins with scree cones, alluvial fans and braided ephemeral channel networks, originated from faulted basin margins within a riftogenic setting possibly related to the global-scale extensional tectonics of Rodinia breakup. After the expansion of the basin, the marine inundation has been correlated to the tr","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 706-737"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141529849","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}
Pub Date : 2024-10-01DOI: 10.1016/j.jop.2024.08.009
Olev Vinn , Jorge Colmenar , Samuel Zamora , Sofia Pereira , Gian Luigi Pillola , Abdullah A. Alkahtane , Saleh Al Farraj , Magdy El Hedeny
Seven Cornulites species, including a new one — Cornulites leonei n. sp., are described from the Upper Ordovician Portixeddu Formation (Katian, stage slices Ka2–3) of Sardinia and the Cavá (lower Katian, stage slice Ka2) and Estana (upper Katian, stage slices Ka3–4) formations of the Pyrenees. The Sardinian and Pyrenean cornulitids represent an adaptation to live in environments with high sedimentation rates and limited hard substrates availability. Their prominent annuli could have had a stabilizing function in the soft sediment that helped cornulitids to keep a favourable position in the sediment to enable suspension feeding. The known Late Ordovician cornulitid diversity in different Gondwana areas is low, usually ranging from one to three taxa, being higher (seven) in Sardinia. Like other benthic groups during the Late Ordovician, the cornulitid tubeworm faunas within the high-latitude peri-Gondwana Province indicate a certain endemism and share morphological and ecological affinities, such as a small body size and tubes with a strikingly small apical angle. Although essentially endemic, some links with cornulitids from the Late Ordovician of Scotland are revealed.
{"title":"Late Ordovician cornulitid tubeworms from high-latitude peri-Gondwana (Sardinia and the Pyrenees) and their palaeobiogeographic significance","authors":"Olev Vinn , Jorge Colmenar , Samuel Zamora , Sofia Pereira , Gian Luigi Pillola , Abdullah A. Alkahtane , Saleh Al Farraj , Magdy El Hedeny","doi":"10.1016/j.jop.2024.08.009","DOIUrl":"10.1016/j.jop.2024.08.009","url":null,"abstract":"<div><div>Seven <em>Cornulites</em> species, including a new one — <em>Cornulites leonei</em> n. sp., are described from the Upper Ordovician Portixeddu Formation (Katian, stage slices Ka2–3) of Sardinia and the Cavá (lower Katian, stage slice Ka2) and Estana (upper Katian, stage slices Ka3–4) formations of the Pyrenees. The Sardinian and Pyrenean cornulitids represent an adaptation to live in environments with high sedimentation rates and limited hard substrates availability. Their prominent annuli could have had a stabilizing function in the soft sediment that helped cornulitids to keep a favourable position in the sediment to enable suspension feeding. The known Late Ordovician cornulitid diversity in different Gondwana areas is low, usually ranging from one to three taxa, being higher (seven) in Sardinia. Like other benthic groups during the Late Ordovician, the cornulitid tubeworm faunas within the high-latitude peri-Gondwana Province indicate a certain endemism and share morphological and ecological affinities, such as a small body size and tubes with a strikingly small apical angle. Although essentially endemic, some links with cornulitids from the Late Ordovician of Scotland are revealed.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 939-953"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263723","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}
Pub Date : 2024-10-01DOI: 10.1016/j.jop.2024.08.008
Gang Liu , Guo-Zhi Wang , Na Li , Hong-Ling He , Nan-Nan Lu , Qing Lei , Zi-Ang Wang
Anomalously positive δ13C values in ancient dolomites are very rare. Dark gray argillaceous rocks of the lacustrine sediments of the Permian Lucaogou Formation are important source rocks in the Junggar Basin, and dolomites of varying thicknesses from 10 cm to 150 cm are often interspersed in argillaceous rocks. Based on the study of petrographic sections, this paper systematically analyzes the carbon and oxygen isotopes of dolomite and discusses the causes of abnormally high carbon isotope values and their significance in reconstructing paleoenvironment and paleoclimate. The results show that carbon isotope values are abnormally high in the dolomite of Lucaogou Formation, and the δ13C value is between +3.2 ‰ PDB and +19.6‰ PDB, with an average of +9.7‰ PDB. The δ18O values range from -17.4‰ PDB to -1.7‰ PDB, with an average of -8.1‰ PDB. From the lower part to the upper part of the Lucaogou Formation, the carbon isotope value gradually increases and becomes increasingly positive, and the carbon isotope of the dolomite deposited near the shore is more positive than that of the dolomite deposited far from the shore. The anomalously positive δ13C of the dolomite is mainly caused by microbial methanogenesis, with some contribution from evaporation. Microorganisms are mainly distributed at the redox interface. Evaporation controls the salinity and fluctuation of the redox interface in sedimentary water. The positive deviation difference in carbon isotopes between nearshore and offshore sedimentary dolomites may be related to the location of the redox interface during deposition. Together, the petrographic features and carbon and oxygen isotope signatures of the sections reflect the gradual evolution of the paleolake from a hydrologically open environment to a hydrologically closed one and the possible transition of the paleoclimate from a relatively warm to an arid condition, which is possibly a geochemical response to global climate change in the Permian period.
{"title":"Characteristics and geological significance of carbon and oxygen isotopes of the Permian Lucaogou Formation dolomite in the southern Junggar Basin, northwestern China","authors":"Gang Liu , Guo-Zhi Wang , Na Li , Hong-Ling He , Nan-Nan Lu , Qing Lei , Zi-Ang Wang","doi":"10.1016/j.jop.2024.08.008","DOIUrl":"10.1016/j.jop.2024.08.008","url":null,"abstract":"<div><div>Anomalously positive δ<sup>13</sup>C values in ancient dolomites are very rare. Dark gray argillaceous rocks of the lacustrine sediments of the Permian Lucaogou Formation are important source rocks in the Junggar Basin, and dolomites of varying thicknesses from 10 cm to 150 cm are often interspersed in argillaceous rocks. Based on the study of petrographic sections, this paper systematically analyzes the carbon and oxygen isotopes of dolomite and discusses the causes of abnormally high carbon isotope values and their significance in reconstructing paleoenvironment and paleoclimate. The results show that carbon isotope values are abnormally high in the dolomite of Lucaogou Formation, and the δ<sup>13</sup>C value is between +3.2 ‰ PDB and +19.6‰ PDB, with an average of +9.7‰ PDB. The δ<sup>18</sup>O values range from -17.4‰ PDB to -1.7‰ PDB, with an average of -8.1‰ PDB. From the lower part to the upper part of the Lucaogou Formation, the carbon isotope value gradually increases and becomes increasingly positive, and the carbon isotope of the dolomite deposited near the shore is more positive than that of the dolomite deposited far from the shore. The anomalously positive δ<sup>13</sup>C of the dolomite is mainly caused by microbial methanogenesis, with some contribution from evaporation. Microorganisms are mainly distributed at the redox interface. Evaporation controls the salinity and fluctuation of the redox interface in sedimentary water. The positive deviation difference in carbon isotopes between nearshore and offshore sedimentary dolomites may be related to the location of the redox interface during deposition. Together, the petrographic features and carbon and oxygen isotope signatures of the sections reflect the gradual evolution of the paleolake from a hydrologically open environment to a hydrologically closed one and the possible transition of the paleoclimate from a relatively warm to an arid condition, which is possibly a geochemical response to global climate change in the Permian period.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 862-882"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263759","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}
Pub Date : 2024-10-01DOI: 10.1016/j.jop.2024.06.006
Peatlands have obvious carbon storage capacity and are crucial in mitigating global climate change. As the end-product of peatlands, coals have preserved a large amount of palaeoenvironmental information. The carbon accumulation rate and the net primary productivity (NPP) of coal-forming peatlands can be used as proxies for recovering palaeoenvironments. A super-thick coal seam (42°35′N, 91°25′E) was developed in the Middle Jurassic Xishanyao Formation in the Shaerhu coalfield in the southern margin of the Tuha (Turpan-Hami) Basin, northwestern China. In this study, we use the time series analysis to identify the periods of Milankovitch orbital cycles in the Gamma-ray curve of this super-thick (124.85 m) coal and then use the obtained cycle periods of 405 ka, 173 ka, 44 ka, 37.6 ka, 22.5 ka to calculate the timeframe of the coal-forming peatlands which ranges from 2703.44 to 2975.11 ka. Considering that the carbon content of the coal seam is 78.32% and the carbon loss during the coalification is about 25.80%, the carbon accumulation rate of the targeted coal seam is estimated to be 58.47–64.34 g C/m2·a, and the NPP is estimated to be 252.28–277.63 g C/m2·a. The main palaeoenvironmental factors controlling the NPP of peatlands are CO2 content, palaeolatitude and palaeotemperature. The reduced NPP values of the palaeo-peatlands in the Shaerhu coalfield can be attributed to the mid-palaeolatitude and/or too low atmospheric CO2 contents. To a certain extent, the NPP of palaeo-peatlands reflects the changes in atmospheric CO2, which can further reveal the dynamic response of the global carbon cycle to climate change. Therefore, predicting the level of NPP in the Middle Jurassic and studying the final destination of carbon in the ecosystem are beneficial to understanding the coal-forming process and palaeoenvironment.
泥炭地具有明显的碳储存能力,对减缓全球气候变化至关重要。作为泥炭地的最终产物,煤炭保存了大量的古环境信息。成煤泥炭地的碳积累率和净初级生产力(NPP)可作为复原古环境的代用指标。中国西北吐哈(吐鲁番-哈密)盆地南缘沙尔湖煤田中侏罗世西山窑地层发育有超厚煤层(42°35′N,91°25′E)。本研究通过时间序列分析,确定了该超厚(124.85 m)煤层伽马射线曲线中的米兰科维奇轨道周期,并利用所得到的405 ka、173 ka、44 ka、37.6 ka、22.5 ka周期,计算出该煤层形成泥炭地的时间范围为2703.44-2975.11 ka。考虑到煤层的含碳量为 78.32%,煤化过程中的碳损失约为 25.80%,估算目标煤层的碳积累率为 58.47-64.34 g C/m-a,NPP 为 252.28-277.63 g C/m-a。控制泥炭地 NPP 的主要古环境因素是 CO 含量、古纬度和古温度。沙尔湖煤田古泥炭地NPP值的降低可归因于中古纬度和/或过低的大气CO含量。古高原NPP在一定程度上反映了大气CO的变化,可以进一步揭示全球碳循环对气候变化的动态响应。因此,预测中侏罗世的NPP水平,研究生态系统中碳的最终去向,有利于了解成煤过程和古环境。
{"title":"Extensive carbon cycle between peatland and vegetation: Insights from high net primary productivity of the Middle Jurassic in northwestern China","authors":"","doi":"10.1016/j.jop.2024.06.006","DOIUrl":"10.1016/j.jop.2024.06.006","url":null,"abstract":"<div><div>Peatlands have obvious carbon storage capacity and are crucial in mitigating global climate change. As the end-product of peatlands, coals have preserved a large amount of palaeoenvironmental information. The carbon accumulation rate and the net primary productivity (NPP) of coal-forming peatlands can be used as proxies for recovering palaeoenvironments. A super-thick coal seam (42°35′N, 91°25′E) was developed in the Middle Jurassic Xishanyao Formation in the Shaerhu coalfield in the southern margin of the Tuha (Turpan-Hami) Basin, northwestern China. In this study, we use the time series analysis to identify the periods of Milankovitch orbital cycles in the Gamma-ray curve of this super-thick (124.85 m) coal and then use the obtained cycle periods of 405 ka, 173 ka, 44 ka, 37.6 ka, 22.5 ka to calculate the timeframe of the coal-forming peatlands which ranges from 2703.44 to 2975.11 ka. Considering that the carbon content of the coal seam is 78.32% and the carbon loss during the coalification is about 25.80%, the carbon accumulation rate of the targeted coal seam is estimated to be 58.47–64.34 g C/m<sup>2</sup>·a, and the NPP is estimated to be 252.28–277.63 g C/m<sup>2</sup>·a. The main palaeoenvironmental factors controlling the NPP of peatlands are CO<sub>2</sub> content, palaeolatitude and palaeotemperature. The reduced NPP values of the palaeo-peatlands in the Shaerhu coalfield can be attributed to the mid-palaeolatitude and/or too low atmospheric CO<sub>2</sub> contents. To a certain extent, the NPP of palaeo-peatlands reflects the changes in atmospheric CO<sub>2</sub>, which can further reveal the dynamic response of the global carbon cycle to climate change. Therefore, predicting the level of NPP in the Middle Jurassic and studying the final destination of carbon in the ecosystem are beneficial to understanding the coal-forming process and palaeoenvironment.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 1016-1028"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141552496","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}
Pub Date : 2024-10-01DOI: 10.1016/j.jop.2024.08.007
Ayush Srivastava , Sudipta Dasgupta , Seema Singh
The Chhasra Formation (CF) of Kutch Basin exemplifies a typical mixed siliciclastic-carbonate system with alternations of biostromal carbonate and fine-grained siliciclastic beds. The CF is subdivided into two members: the lower Claystone (CM) and the upper Siltstone (SM) member. Three CM outcrops (P1-P3) comprising buried palaeosols that formed under a specific environmental set-up involving imperfectly to poorly drained conditions, are exposed along the Berwali River. The biostromal carbonate beds, alternating with the palaeosols, contain invertebrate bioclasts (bivalves, gastropods, echinoids, etc.) and are characterized by a paucispecific firmground Thalassinoides ichnofabric. At section P1, below the contact between the underlying palaeosol and overlying carbonate, Thalassinoides transforms into firmground Gyrolithes inside the palaeosol forming a compound ichnotaxon. The palaeosol intervals of sections P1 and P2 consist of a Vondrichnus‒Termitichnus‒root trace ichnofabric defining the Termitichnus ichnofacies. At section P3, lenses of fully bioturbated siltstones with a monospecific firmground Thalassinoides ichnofabric can be observed within an overall silty palaeosol horizon, thereby, locally cross-cutting the pedogenic features. The ichnofabrics of section P3 indicate polyphase pedogenesis with three stages: (1) initial stage: pedogenesis in siltstone of undefined depositional affinity which was obscured by pedogenic processes, (2) transient stage: recurring marine incursions and colonization by crustaceans within the lens-shaped palaeotopographic depressions overprinting the palaeosol, and (3) final stage: subaerial exposure and another preserved phase of pedogenesis. The CM shows an apparent low-order T–R (transgressive-regressive) cyclicity within a 3rd-order TST (transgressive systems tract) that is supported by pedogenic intensity, ichnofabrics, and reciprocal sedimentation near the Miocene basin margin, though the cyclicity can be the result of both autogenic and/or lower-order allogenic changes.
{"title":"Lower-order transgressive–regressive cycles within a higher-order transgression at the basin margin: an aberrant intercalation of palaeosol and biostromal ichnofabrics from the early Miocene Kutch Basin, India","authors":"Ayush Srivastava , Sudipta Dasgupta , Seema Singh","doi":"10.1016/j.jop.2024.08.007","DOIUrl":"10.1016/j.jop.2024.08.007","url":null,"abstract":"<div><div>The Chhasra Formation (CF) of Kutch Basin exemplifies a typical mixed siliciclastic-carbonate system with alternations of biostromal carbonate and fine-grained siliciclastic beds. The CF is subdivided into two members: the lower Claystone (CM) and the upper Siltstone (SM) member. Three CM outcrops (P1-P3) comprising buried palaeosols that formed under a specific environmental set-up involving imperfectly to poorly drained conditions, are exposed along the Berwali River. The biostromal carbonate beds, alternating with the palaeosols, contain invertebrate bioclasts (bivalves, gastropods, echinoids, etc.) and are characterized by a paucispecific firmground <em>Thalassinoides</em> ichnofabric. At section P1, below the contact between the underlying palaeosol and overlying carbonate, <em>Thalassinoides</em> transforms into firmground <em>Gyrolithes</em> inside the palaeosol forming a compound ichnotaxon. The palaeosol intervals of sections P1 and P2 consist of a <em>Vondrichnus</em>‒<em>Termitichnus</em>‒root trace ichnofabric defining the <em>Termitichnus</em> ichnofacies. At section P3, lenses of fully bioturbated siltstones with a monospecific firmground <em>Thalassinoides</em> ichnofabric can be observed within an overall silty palaeosol horizon, thereby, locally cross-cutting the pedogenic features. The ichnofabrics of section P3 indicate polyphase pedogenesis with three stages: (1) initial stage: pedogenesis in siltstone of undefined depositional affinity which was obscured by pedogenic processes, (2) transient stage: recurring marine incursions and colonization by crustaceans within the lens-shaped palaeotopographic depressions overprinting the palaeosol, and (3) final stage: subaerial exposure and another preserved phase of pedogenesis. The CM shows an apparent low-order T–R (transgressive-regressive) cyclicity within a 3rd-order TST (transgressive systems tract) that is supported by pedogenic intensity, ichnofabrics, and reciprocal sedimentation near the Miocene basin margin, though the cyclicity can be the result of both autogenic and/or lower-order allogenic changes.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 906-923"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195272","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}
Pub Date : 2024-10-01DOI: 10.1016/j.jop.2024.08.001
Gisella M. Della Costa, Guillermo L. Albanesi
One of the largest Ordovician sea-level rises is the Evae transgression, which occurs in the lower part of the Oepikodus evae Biozone, indicative of a late Floian age. Specifically, the characteristics associated with the highstand of this event included: a higher proportion of specimens of the index species O. evae than other species, a diversity acme in the evae Biozone, and a reduction of biogeographic barriers that resulted in a high proportion of species with cosmopolitan distribution. In the present contribution, the pattern of species similarity among Laurentia, Argentine Precordillera, Baltica, Kazakhstania, South China, and Australia is evaluated with a multiple coefficient analysis including only the sections that recorded the highstand of the Evae transgression. Moreover, the effect of possible terrestrial, latitudinal, physicochemical barriers and palaeogeographic distance on the species distribution is statistically analysed. Our results show a global pattern of conodont species distribution that is highly constrained by the tested palaeoenvironmental factors. This suggests that contrary to what was expected for a prominent transgression, faunal barriers did not decrease significantly during the Evae drowning peak.
{"title":"Global pattern of conodont similarity and faunal constraints during the highstand of the Evae eustatic event (late Floian, Lower Ordovician)","authors":"Gisella M. Della Costa, Guillermo L. Albanesi","doi":"10.1016/j.jop.2024.08.001","DOIUrl":"10.1016/j.jop.2024.08.001","url":null,"abstract":"<div><div>One of the largest Ordovician sea-level rises is the Evae transgression, which occurs in the lower part of the <em>Oepikodus evae</em> Biozone, indicative of a late Floian age. Specifically, the characteristics associated with the highstand of this event included: a higher proportion of specimens of the index species <em>O. evae</em> than other species, a diversity acme in the <em>evae</em> Biozone, and a reduction of biogeographic barriers that resulted in a high proportion of species with cosmopolitan distribution. In the present contribution, the pattern of species similarity among Laurentia, Argentine Precordillera, Baltica, Kazakhstania, South China, and Australia is evaluated with a multiple coefficient analysis including only the sections that recorded the highstand of the Evae transgression. Moreover, the effect of possible terrestrial, latitudinal, physicochemical barriers and palaeogeographic distance on the species distribution is statistically analysed. Our results show a global pattern of conodont species distribution that is highly constrained by the tested palaeoenvironmental factors. This suggests that contrary to what was expected for a prominent transgression, faunal barriers did not decrease significantly during the Evae drowning peak.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"13 4","pages":"Pages 883-905"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195309","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}