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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 深湖盆地泥质堆积的沉积动力学和沉积模型:中国北部鄂尔多斯盆地上三叠统长-7组的案例研究
Pub Date : 2024-10-01 DOI: 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.
深湖盆地页岩已成为大陆页岩油气勘探的重点。为揭示深湖盆地泥岩沉积动力学特征,本研究采用岩芯观察、薄片检验、X射线衍射和QEMSCAN(扫描电镜矿物定量评价)相结合的方法,分析了鄂尔多斯盆地延长地层(上三叠统)长-7组泥岩的沉积特征,建立了深湖盆地泥岩堆积的沉积模型。本研究确认了长-7 组的四种泥岩岩相:(1)层状粉砂质泥岩,一般发育 "粉砂-粘土 "二元组合或 "粉砂-粘土-有机质 "三元组合;(2)层状泥岩,主要由深灰色和灰黑色泥岩夹粉砂质泥岩组成;(3) 块状泥岩,内部呈均匀分布的石英、粘土和碳酸盐矿物,也有少量有机碎屑;以及 (4) 层状页岩,一般由粘土层和前两者的有机层组成。沉积物的供应、地形坡度和洪水强度共同控制着重力流的演变以及长-7 组泥岩的搬运和沉积。造山运动的影响为重力流的形成提供了地形坡度、水深、源区丰富的沉积物和触发机制。湿润事件引发的洪水为沉积物迁移提供了动力。长-7 组的泥质沉积主要与超热流的泥质运移和沉积以及浮力羽流絮凝的快速沉积有关。综合各种触发机制和泥质运移沉积过程,建立了深湖盆地页岩堆积的综合演化模型。
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引用次数: 0
Girvanella fossils from the Phanerozoic: Distribution, evolution and controlling factors 新生代的吉尔瓦内拉化石:分布、演化和控制因素
Pub Date : 2024-10-01 DOI: 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。
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引用次数: 0
High-frequency lacustrine sequence stratigraphy of clastic lakes: lessons from ancient successions 碎屑湖的高频湖相序列地层学:古代演替的启示
Pub Date : 2024-10-01 DOI: 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
层序地层学的概念和方法为进行地层分析提供了新的工具,使我们能够更好地理解沉积模型和盆地演化。传统层序地层学认识到的主要控制和沉积要素(如地表、系统道、副层序等)是为与海洋有关的系统设计的。相比之下,湖相演替的层序地层学要复杂得多,而且人们对其了解甚少,因为它不是由海平面变化驱动的,而是由构造和高频气候周期之间复杂的相互作用驱动的。通过对湖沼系统水平衡的全面分析,可以识别三种类型的湖泊状况:充水不足型、平衡充水型和过度充水型湖泊。了解古代演替中的湖泊条件是揭示湖相序列地层学的基础,因为这些条件有效地控制着水盐度、内部堆积模式和系统道的特征。灌注不足的湖泊是水文封闭的湖泊,因此,在高频率的干湿气候周期的驱动下,湖泊水位会剧烈波动。在湿润时期,河流提供水和沉积物,从而形成了在横断系统道(TST)期间积累的细-薄-向上的基本沉积序列(EDS)。与此相反,干旱期的特点是湖泊水位相对下降,湖泊边缘地区在回归系统(RST)期间露出地面以下。湖水盐度可从咸盐到高盐度波动。平衡充填湖泊是部分封闭的湖泊,因此同时具有充填不足湖泊和充填过度湖泊的特征。在 TST 期间,湖泊处于填充不足的状态,因此,引入的水和沉积物会积累一个细化的上升区间,直至在最大洪水期间达到溢出点。RST 是在湖泊过度充盈的情况下积累的,沿岸三角洲和相关的水下三角洲沉积逐渐变粗。湖水盐度从咸水到淡水不等。溢满的湖泊在水文上是开放的湖泊。大多数沉积物是在陆相沉积时期堆积的,形成了粗化向上的阶式沿岸沉积,以及相关的水下三角洲。所有被过度填充的湖泊都是淡水湖。沉降对于湖泊沉积的长期保存至关重要。在缺乏沉降的地区,湖泊可以暂时储存水和沉积物,但这些沉积物不会保存在地层记录中。因此,人们认识到有两种类型的湖泊:1) 下沉湖泊,具有永久的容纳空间;2) 悬湖,具有临时的容纳空间。虽然悬湖不能永久储存沉积物,但它们对湖泊层序地层学至关重要,因为它们可以通过近乎瞬时释放大量的水淹没下沉湖泊,为富含有机质的页岩的堆积创造有利条件。这种来自悬湖的快速洪水诱发了强迫横断(FT),这是一种大规模的快速横断(异相),与来自当地源区的正常沉积物和水供应无关。
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引用次数: 0
A combined tectono-climatic control on Holocene sedimentation in Ladakh Himalaya, India: Clues from Anisotropy of Magnetic Susceptibility (AMS) of lake sediments 印度拉达克喜马拉雅全新世沉积的构造-气候综合控制:湖泊沉积物磁感应强度(AMS)各向异性提供的线索
Pub Date : 2024-10-01 DOI: 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.
位于雷-拉达克喜马拉雅山印度河北岸、全新世时代的斯皮图克古湖序列(Spituk Palaeolake Sequence,SPSS)中厚度为 27.8 米的软沉积泥浆序列(10.5-3.25 千年)的磁感应强度(AMS)各向异性数据显示了喜马拉雅山沉积作用的构造与气候动力学效应。沉积序列由风化砂层和冰川流泥流沉积交替组成,可细分为较古老的末期冰川第一阶段(LGP 1)和较年轻的末期冰川第二阶段(LGP 2),每个阶段的终点都有厚度≤1 米的砾石层,这些砾石层是由于冰川融化而沉积下来的。目前的 AMS 数据以及之前公布的沉积学信息证实,LGP 1 和 LGP 2 阶段的泥石流沉积是在冰川-河流条件下的湖泊环境中沉积的。不过,LGP 1 期和 LGP 2 期可能分别存在向西北和东北方向的微弱河流。终止 LGP 1 和 LGP 2 的冰川床似乎分别是由气候变暖和构造活动形成的。因此,全新世喜马拉雅山沉积同时受到气候和构造活动的影响。然而,在本研究中,终止 LGP 2 的砾石层厚度(0.8 米)仅占所研究的 SPSS 总厚度(28 米)的 2.8 Vol %,这表明构造活动对研究区及其周边地区喜马拉雅山的生长影响较小。
{"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}
引用次数: 0
Evolution of Neoproterozoic siliciclastic Kerur Formation in the light of sequence stratigraphic framework: Badami Basin, Karnataka, India 从层序地层框架看新新生代硅质碎屑岩凯鲁尔地层的演化:印度卡纳塔克邦巴达米盆地
Pub Date : 2024-10-01 DOI: 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
基于现场的沉积学、最先进的岩相分析和层序地层框架分析揭示了当地和全球构造、盆地边缘坡度、气候和相对海平面(RSL)变化对印度卡拉吉超群巴达米组内新新生代凯鲁尔地层的沉积模式和演化的影响。整个演替显示了三个主要的沉积周期。地貌研究和河流建筑元素分析表明,沉积环境和古地理环境存在很大差异。在第一个沉积周期中,可以看到从盆地边缘冲积锥沉积到辫状系统的过渡,最初是波动的短时流,然后是较稳定的半常年流,这是对地下水位上升导致沉积坡度减小的反应。最初的冲积锥和高坡地区的辫状短时溪流被认为是低容纳系统(LAST)的产物,而代表最初裂谷轴向河流的具有稳定水流的半常年系统似乎是高容纳系统(HAST)的产物。第 2 个周期以常年稳定的辫状河系统为起点,向上渐变为浅海演替,由波浪为主、分选良好的砂岩组成,底部为颗粒状的横断滞后层。因此,2 个周期的最底层河道区间构成了低洼地带(LST)。海洋演替代表了从外陆架近海到前滩-海滩环境的沉积,由最初变深变细的上跨式系统剖面(TST)和随后变粗变浅的上高台系统剖面(HST)组成,两者之间为最大海洋洪积面(MFS),由富含页岩的凝结带划分。第 3 周期的冲积扇和辫状河沉积物不断增大,出现范围有限,仅代表低容积系地层(LAST),底部有一个次生不整合带。该盆地显然始于西段,在第 1 个周期沉积之后,盆地边缘断层的第一次大恢复期间向东扩展。第 2 周期在整个盆地沉积后,第 3 周期仅在西段的断层系统第二次大更新过程中得到了有限制的发展。所提出的沉积模型得到了已确立的地质年代制约因素的支持,表明第 1 周期的沉积始于碎石锥、冲积扇和辫状短流河道网络,它们起源于断裂成因环境中的断裂盆地边缘,可能与罗迪尼亚断裂的全球尺度扩展构造有关。在盆地扩张之后,海洋淹没与断裂后成熟阶段可能发生的横断有关。
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引用次数: 0
Late Ordovician cornulitid tubeworms from high-latitude peri-Gondwana (Sardinia and the Pyrenees) and their palaeobiogeographic significance 来自高纬度近冈瓦纳地区(撒丁岛和比利牛斯山)的晚奥陶世矢车菊管虫及其古生物地理学意义
Pub Date : 2024-10-01 DOI: 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.
该研究描述了撒丁岛上奥陶统 Portixeddu 地层(卡蒂亚期,Ka2-3阶段)和比利牛斯山脉的 Cavá(下卡蒂亚期,Ka2阶段)和 Estana(上卡蒂亚期,Ka3-4阶段)地层中的 7 个物种,其中包括一个新物种--n. sp.。撒丁岛和比利牛斯山脉的粟粒石代表了对生活在高沉积速率和有限硬基质环境中的适应。它们突出的环纹可能在松软的沉积物中具有稳定作用,有助于矢车菊鱼在沉积物中保持有利位置,从而实现悬浮取食。在冈瓦纳不同地区,已知的晚奥陶世粟粒虫多样性很低,通常只有一到三个类群,撒丁岛的类群较多(七个)。与晚奥陶世的其他底栖生物类群一样,高纬度近冈瓦纳省的粟管虫动物群也具有一定的地方性,并在形态和生态方面具有共同之处,如体型较小,管体顶端角度明显较小。虽然基本上是地方性的,但与苏格兰奥陶纪晚期的粟壳类动物有一些联系。
{"title":"Late Ordovician cornulitid tubeworms from high-latitude peri-Gondwana (Sardinia and the Pyrenees) and their palaeobiogeographic significance","authors":"Olev Vinn ,&nbsp;Jorge Colmenar ,&nbsp;Samuel Zamora ,&nbsp;Sofia Pereira ,&nbsp;Gian Luigi Pillola ,&nbsp;Abdullah A. Alkahtane ,&nbsp;Saleh Al Farraj ,&nbsp;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}
引用次数: 0
Characteristics and geological significance of carbon and oxygen isotopes of the Permian Lucaogou Formation dolomite in the southern Junggar Basin, northwestern China 中国西北准噶尔盆地南部二叠系芦草沟组白云岩碳、氧同位素特征及其地质意义
Pub Date : 2024-10-01 DOI: 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.
古白云岩中异常的正δC 值非常罕见。二叠系卢草沟组湖相沉积的深灰色霰粒岩是准噶尔盆地的重要源岩,厚度从10厘米到150厘米不等的白云岩往往夹杂在霰粒岩中。本文在岩相切片研究的基础上,系统分析了白云岩的碳氧同位素,探讨了碳同位素值异常偏高的原因及其对重建古环境和古气候的意义。结果表明,卢草沟组白云岩碳同位素值异常偏高,δC值介于+3.2‰PDB和+19.6‰PDB之间,平均为+9.7‰PDB。δO值介于-17.4‰ PDB和-1.7‰ PDB之间,平均值为-8.1‰ PDB。从卢草沟组的下部到上部,碳同位素值逐渐增大,且越来越正,近岸沉积的白云岩的碳同位素比远岸沉积的白云岩的碳同位素更正。白云岩碳同位素的异常正值主要是由微生物甲烷化作用引起的,蒸发也有一定的作用。微生物主要分布在氧化还原界面。蒸发控制着沉积水的盐度和氧化还原界面的波动。近岸和近海沉积白云岩碳同位素的正偏差差异可能与沉积过程中氧化还原界面的位置有关。这些断面的岩相特征和碳氧同位素特征共同反映了古湖从水文开放环境逐渐演变为水文封闭环境,以及古气候可能从相对温暖过渡到干旱状态,这可能是对二叠纪全球气候变化的地球化学响应。
{"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 ,&nbsp;Guo-Zhi Wang ,&nbsp;Na Li ,&nbsp;Hong-Ling He ,&nbsp;Nan-Nan Lu ,&nbsp;Qing Lei ,&nbsp;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}
引用次数: 0
Extensive carbon cycle between peatland and vegetation: Insights from high net primary productivity of the Middle Jurassic in northwestern China 泥炭地与植被之间广泛的碳循环:中国西北部中侏罗世高净初级生产力的启示
Pub Date : 2024-10-01 DOI: 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。
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引用次数: 0
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 盆地边缘高阶跃迁中的低阶跃迁-跃迁循环:印度早中新世卡奇盆地古沉积物和生物叠层生物织物的异常交错
Pub Date : 2024-10-01 DOI: 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 VondrichnusTermitichnus‒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.
库奇盆地的查斯拉地层(CF)是典型的硅质岩-碳酸盐岩混合体系,由生物质碳酸盐岩和细粒硅质岩床交替组成。碳酸盐岩被细分为两个部分:下部的粘土岩(CM)和上部的粉砂岩(SM)。三个 CM 露头(P1-P3)由埋藏的古溶胶组成,它们是在特定的环境条件下形成的,排水条件不完善到很差,沿 Berwali 河出露。与古溶胶交替出现的生物质碳酸盐床含有无脊椎动物生物碎屑(双壳类、腹足类、回声类等),其特征是具有低特异性的坚硬地层生物结构。在 P1 段,在下层古沉积与上覆碳酸盐岩的接触面以下,古沉积内部转变为坚硬地层,形成了复合的生物群。P1 和 P2 断面的古沉积层间由根痕迭层组成,确定了迭层结构。在 P3 断面,在整体淤泥质古溶层中可以观察到透镜状的完全生物扰动的粉砂岩,其上有单一的坚硬地层生物网状结构,从而在局部与成土特征交叉。P3 断面的生物网状结构表明多相成土过程分为三个阶段:(1) 初始阶段:成土过程掩盖了未确定沉积亲缘关系的粉砂岩中的成土过程;(2) 短暂阶段:在古壤土上的透镜状古地形凹陷中反复出现的海洋入侵和甲壳类动物的定殖;(3) 最终阶段:次大气暴露和另一个保留的成土阶段。中新世盆地显示了一个明显的低阶 T-R(横断-递减)循环,它位于三阶 TST(横断系统道)中,并得到了成土强度、出土织物和中新世盆地边缘附近往复沉积作用的支持,尽管这种循环可能是自生和/或低阶异生变化的结果。
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引用次数: 0
Global pattern of conodont similarity and faunal constraints during the highstand of the Evae eustatic event (late Floian, Lower Ordovician) Evae 生态事件高位期(下奥陶纪晚期弗洛期)全球锥齿类相似性模式和动物群制约因素
Pub Date : 2024-10-01 DOI: 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.
奥陶纪最大的海平面上升事件之一是埃瓦(Evae)横断面,发生在生物区的下部,显示了弗洛纪晚期的特征。具体来说,与这一事件高位相关的特征包括:指数物种标本的比例高于其他物种;生物区的多样性达到顶峰;生物地理屏障减少,导致具有世界性分布的物种比例很高。在本论文中,我们通过多元系数分析评估了劳伦提亚、阿根廷前山地带、波罗的海、哈萨克斯坦、华南和澳大利亚之间的物种相似性模式,其中只包括记录了埃瓦河大断裂高潮的地段。此外,还利用 Raup-Crick 指数分析了可能存在的陆地、纬度、物理化学障碍和古地理距离对物种分布的影响。我们的研究结果表明,锥齿类物种的全球分布模式受到所测试的古环境因素的高度制约。这表明,在埃瓦河溺水高峰期,动物障碍并没有明显减少,这与人们对一个突出的横断面的预期相反。
{"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,&nbsp;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}
引用次数: 0
期刊
Journal of Palaeogeography
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