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Ecological stability of late Maastrichtian benthic foraminifera amidst Deccan volcanism 德干火山活动中马斯特里赫特晚期底栖有孔虫的生态稳定性
IF 2 Pub Date : 2025-12-06 DOI: 10.1016/j.jop.2025.100317
Subham Patra , Kebenle Kesen , Gerta Keller , Thierry Adatte , Jahnavi Punekar
The late Maastrichtian witnessed profound disruptions in biogeochemical cycles, leading to the fifth mass extinction at the Cretaceous–Paleogene (K/Pg) boundary. At Bidart section (France), the final ∼60 kyr of the Maastrichtian coincide with mercury (Hg) peaks, low magnetic susceptibility, evidence of biological stress and taphonomic alteration in planktic foraminifera, indicative of an ocean acidification event. While this event primarily appears to be a surface-ocean phenomenon, previous studies also documented a minor rise in benthic foraminiferal test fragmentation beginning 0.5 m below the K/Pg boundary, with a pronounced spike at the boundary itself.
A detailed investigation of benthic foraminifera in biozone CF1 at Bidart section (France) reveals a diverse and balanced assemblage preceding the K/Pg boundary, with minimal taphonomic alterations. At the K/Pg boundary, infaunal populations diminished, diversity declined sharply, test fragmentation intensified, yet paradoxically, the absolute abundance of genera rose markedly. Preferential preservation is evident in the dominance of robust taxa (Cibicidoides spp., Coryphostoma spp.), while a high fragmentation index reflects strong taphonomic dissolution and time-averaging. A plausible explanation for this could be CO2-rich waters mixing into the ocean interior over 100–1000 years, driving dissolution during the ∼10,000-year deposition of the K/Pg boundary red clay. The stark contrast between the planktic and benthic census and morphometric data at Bidart section clearly constrains any Deccan-related calcification stress to the surface mixed layer. Lastly, the integrated planktic and benthic considerations re-emphasize a need to carefully separate taphonomic signals from true ecological stress.
马斯特里赫特晚期生物地球化学循环被严重破坏,导致了白垩纪-古近纪(K/Pg)界线上的第五次大灭绝。在Bidart剖面(法国),马斯特里赫特的最后~ 60 kyr与汞(Hg)峰值、低磁化率、浮游有孔虫生物应激和地学改变的证据一致,表明海洋酸化事件。虽然这一事件主要是表面海洋现象,但先前的研究也记录了底栖有孔虫试验破碎的轻微上升,从K/Pg边界以下0.5 m开始,边界本身出现明显的峰值。对法国Bidart剖面CF1生物带底栖有孔虫的详细调查表明,在K/Pg边界之前,底栖有孔虫的组合多样化且平衡,地层学变化很小。在K/Pg边界上,动物种群数量减少,多样性急剧下降,试验破碎化加剧,而属的绝对丰度却显著上升。较强的分类群(Cibicidoides spp., Coryphostoma spp.)具有明显的优先保存优势,而较高的碎片化指数反映了较强的埋藏分解和时间平均。对此,一个合理的解释可能是,在100-1000年的时间里,富含二氧化碳的水混合到海洋内部,在K/Pg边界红粘土的沉积过程中,导致了溶解。Bidart剖面的浮游生物和底栖生物普查数据与形态测量数据之间的鲜明对比,清楚地限制了任何与decan有关的钙化应力到表面混合层。最后,对浮游生物和底栖生物的综合考虑再次强调需要仔细地将地学信号与真正的生态压力分开。
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引用次数: 0
Control of deep-water sedimentation on rift margin by non-coaxial fault linkage system: a case study from the steep slope of the Dongying Depression, Bohai Bay Basin, China 非同轴断裂联动系统对裂谷边缘深水沉积的控制——以渤海湾盆地东营坳陷陡坡带为例
IF 2 Pub Date : 2025-12-06 DOI: 10.1016/j.jop.2025.100318
Rong-Heng Tian , Ben-Zhong Xian , Qian-Ran Wu , Peng Chen , Naveed Ur Rahman , Lin Zhao , Peng-Yu Wang , Wen-Miao Zhang
Understanding the evolution of the segmented synsedimentary fault linkage, which controls the accommodation development, sediment infill, and stratigraphic architecture, is essential for reconstructing rift histories and exploring natural resources. This study investigates the tectono-sedimentary processes in the steep slope of the Dongying Depression within the Bohai Bay Basin rift system, eastern China by utilizing three-dimensional seismic and drilling data. A classification scheme for non-coaxial extensional fault linkage styles is proposed, categorizing them into two types—partial linkage and through-going hard linkage—with eight subtypes based on geometric architectures, evolutionary stages, and segment-scale activity. Statistical analysis of the length and separation distance of the main border fault (the Chennan Fault) reveals that non-coaxial linkage systems are pervasive along the northern rift margin of the Dongying Depression. These systems controlled the development of its irregular zigzag geometry. Furthermore, analysis of non-coaxial convergent fault linkage processes provides the most plausible explanation for the initial morphology of the large paleo-gullies observed on the steep slope. Seismic-geomorphologic mapping and borehole dataset allow us to constrain the spatial and architectural variability of depositional systems along the rift margin. The results demonstrate that non-coaxial fault linkage processes control deep-water depositional types: basinal fans dominate during partial linkage phases, while nearshore subaqueous fans develop under through-going linkage conditions. Non-coaxial fault segment activity influences sediment input directions: uniform fault activity promotes longitudinal transport systems, whereas heterogeneous activity controls oblique delivery along dominant fault segments. This study enhances the understanding of non-coaxial fault systems and their sedimentary responses, providing a reliable basis for hydrocarbon exploration in the steep slopes of lacustrine rift basins.
研究控制可容纳发育、沉积充填和地层构型的分段同沉积断裂链的演化,对于重建裂谷历史和勘探自然资源具有重要意义。利用三维地震资料和钻井资料,研究了渤海湾盆地裂谷系东营坳陷陡坡带的构造-沉积过程。提出了非同轴张拉断层连接类型的分类方案,根据构造、演化阶段和段尺度活动性将其划分为部分连接和贯通连接两种类型,并划分为8个子类型。对主边界断裂(陈南断裂)长度和分离距离的统计分析表明,东营坳陷北部断陷边缘普遍存在非同轴联动体系。这些系统控制着不规则之字形几何的发展。此外,对非同轴会聚断层联动过程的分析为陡坡上观测到的大型古沟的初始形态提供了最合理的解释。地震地貌填图和钻孔数据使我们能够约束裂谷边缘沉积体系的空间和结构变异性。结果表明,非同轴断裂联动过程控制着深水沉积类型,在部分联动阶段以盆地扇为主,而在全程联动条件下则发育近岸水下扇。非同轴断层段活动影响沉积物输入方向:均匀断层活动促进纵向输送系统,而非均匀断层活动控制沿主要断层段的斜向输送。该研究增强了对非同轴断裂体系及其沉积响应的认识,为湖相裂谷盆地陡坡带油气勘探提供了可靠的依据。
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引用次数: 0
Organic matter accumulation in limestone-marl alternations of the middle Permian Maokou Formation, Sichuan Basin, China, and its response to the interglacial–glacial transition 四川盆地中二叠统茅口组灰岩-泥灰岩交替带有机质聚集特征及其对间冰期-冰期过渡的响应
IF 2 Pub Date : 2025-11-28 DOI: 10.1016/j.jop.2025.100312
Feng-Bin Liu , Liang-Biao Lin , Bo-Lin Zhang , Yu Yu , Yong Dan , Si-Yu Liu
The deposition of limestone-marl alternations (LMAs) with elevated organic matter (OM) content within the Middle Permian (Guadalupian) Maokou Formation of the Sichuan Basin, China, was influenced by the interglacial–glacial transition. However, the mechanisms of OM accumulation remain unclear. This study examines OM accumulation in the first member of the Maokou Formation (i.e., the Mao I Member) from the Hegou and Zaodu sections using multiple geochemical proxies, with a focus on its response to climatic shifts during the interglacial–glacial transition. OM accumulation was primarily influenced by this climatic transition through two interrelated processes: (1) by regulating the intensity of chemical weathering (Rb/Sr) in nearshore shallow-platform environments, which in turn controlled terrigenous nutrient input (Ti/Al); and (2) by enhancing upwelling in distal deeper waters (Cd/Mo), thereby stimulating primary productivity (OCAR, PAR, CuXS, and NiXS). These mechanisms overcame the typical constraints of an oxygenated carbonate platform setting (where Ce anomalies are mostly <1.3), exerting a stronger control on OM accumulation than redox conditions. As glacial conditions intensified, the dominant mode of OM accumulation in the Mao I Member shifted from a detrital-driven regime—characterized by high terrigenous input (Ti/Al) and clay-mediated preservation (Al2O3)—to a hybrid system jointly regulated by both detrital input and upwelling-related nutrient delivery (Cd/Mo). In this latter phase, enhanced upwelling compensated for the decline in terrigenous nutrients. OM accumulation persisted even under oxygenated bottom-water conditions. This finding contrasts with the anoxia-dependent models typical of high OM shales and underscores the predominance of productivity over preservation factors in this icehouse carbonate platform. The transition toward glacial conditions is evidenced by the decreasing Rb/Sr ratios, indicating weakened chemical weathering, and declining Ti/Al ratios, signifying reduced terrigenous input. Our findings elucidate how multi-factor interactions govern OM accumulation in mixed carbonate–clastic systems and provide valuable constraints for predicting the stratigraphic distribution and quality of potential hydrocarbon source rocks in such settings.
四川盆地中二叠统瓜达鲁普系茅口组灰泥-泥灰岩互变沉积受间冰期-冰期过渡的影响,有机质含量较高。然而,OM积累的机制尚不清楚。利用多种地球化学指标,研究了河沟段和灶渡段茅一段OM的富集特征,重点研究了其对间冰期-冰期气候变化的响应。这种气候转变主要通过两个相互关联的过程影响有机质积累:(1)通过调节近岸浅台地环境的化学风化强度(Rb/Sr),从而控制陆源养分输入(Ti/Al);(2)通过增强远端深水(Cd/Mo)的上升流,从而提高初级生产力(OCAR、PAR、CuXS和NiXS)。这些机制克服了典型的含氧碳酸盐岩台地环境的限制(其中Ce异常大多为<;1.3),比氧化还原条件对OM聚集的控制更强。随着冰川条件的加剧,茂一段有机质的主要积累模式从碎屑驱动模式(以高陆源输入(Ti/Al)和粘土保存(Al2O3)为特征)转变为碎屑输入和上升流相关的养分传递(Cd/Mo)共同调节的混合系统。在后一阶段,增强的上升流弥补了陆源营养物质的减少。即使在含氧的底水条件下,OM积累也持续存在。这一发现与高有机质页岩典型的缺氧依赖模型形成对比,并强调了在这个冰库碳酸盐岩台地中,生产力比保存因素更重要。Rb/Sr比值下降,表明化学风化作用减弱;Ti/Al比值下降,表明陆源输入减少。我们的发现阐明了多因素相互作用如何控制混合碳酸盐岩-碎屑体系中OM的聚集,并为预测这种环境下潜在烃源岩的地层分布和质量提供了有价值的约束。
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引用次数: 0
Grallatorid–eubrontid tridactyl track assemblages from Lower Jurassic, Sichuan Province, China: Insights into theropod diversity, locomotion and behavior 四川下侏罗统食食兽脚亚目-前翼类三趾亚目足迹组合:对兽脚亚目多样性、运动和行为的认识
IF 2 Pub Date : 2025-11-27 DOI: 10.1016/j.jop.2025.100311
Li-Da Xing , Shan Jiang , Qi-Yan Chen , Yong Ye , Guang-Zhao Peng , Anthony Romilio , Hendrik Klein , Yan-Yi Gong
The Sichuan Basin in southwestern China is home to the most extensive theropod track record in the Lower Jurassic of China, comprising a range of minute-to medium-sized tracks that form the grallatorid–eubrontid (GE) plexus. The majority of these had previously been discovered in the Ma’anshan Member of the Ziliujing Formation. New material described herein is from the Wuli tracksite that suggests a flourishing paleoecological scene in a temporary waterfront habitat. Upon reviewing the GE plexus at different scales, we consider the locomotion style of these early theropod trackmakers, which likely included the ‘grounded-running’ gait of extant birds, as well as the possibility of a tail trace that may be related to intra- or interspecific interactions.
中国西南部的四川盆地是中国下侏罗统最广泛的兽脚亚目足迹记录的所在地,包括一系列分钟至中等大小的足迹,形成了grallatorid-eubrontid (GE)丛。其中大部分已在自流井组马鞍山段发现。本文描述的新材料来自Wuli轨道遗址,表明在一个临时的滨水栖息地有一个繁荣的古生态场景。在回顾了不同尺度的GE神经丛后,我们考虑了这些早期兽脚亚目追踪者的运动方式,其中可能包括现存鸟类的“地面奔跑”步态,以及可能与种内或种间相互作用有关的尾巴痕迹的可能性。
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引用次数: 0
Late Jurassic manganese microbial carbonates of West Siberian oil and gas basin: Diagnostic features, environmental sedimentation, secondary transformations 西西伯利亚油气盆地晚侏罗世锰微生物碳酸盐:诊断特征、环境沉积、次生转化
IF 2 Pub Date : 2025-11-27 DOI: 10.1016/j.jop.2025.100316
Latypova Margarita , Gafurova Dina , Churkina Valeria , Kalmykov Anton , Kalmykov Georgy
This study focuses on the investigation of Late Oxfordian–Early Tithonian manganese microbial carbonates (MC) found at the top of the Georgiev regional stage in the Western Siberian oil and gas basin. In some isolated areas, these MC are oil reservoirs. However, these rocks are still one of the least studied sediments in the carbonate interval at the boundary of the Bazhenov and Georgiev subregional stage. We have described their geochemical, lithological and mineralogical composition in detail. Based on the characteristics of MC, we assumed their formation settings. The elevated MnO content, associated with microbial processes, and the high concentration of biophilic elements, both suggest the active involvement of organic matter in the formation and development of microbial sediments. The isotopic composition of carbon in the microbial carbonates further supports a biogenic source of carbon dioxide playing an important role in the formation of these deposits. We have established that the Late Jurassic manganese MC were intensely secondary altered, partially recrystallized and calcified by catagenetic processes. Isometric pyrite crystal aggregates with kutnohorite fragments were formed at the contacts between kutnohorite and calcite zones. We suggest that the presence of caverns and high reservoir potential in the microbial carbonates from the Yem-Egovskaya field of the Krasnoleninsky arch may be attributed to intense secondary catagenetic alterations.
本研究对西西伯利亚盆地格奥尔基耶夫区域阶段顶部发现的晚牛津世—早铁东世锰微生物碳酸盐(MC)进行了研究。在一些孤立的地区,这些MC是油藏。然而,这些岩石仍然是巴切诺夫和格奥尔基耶夫分区域阶段边界碳酸盐层间研究最少的沉积物之一。我们详细地描述了它们的地球化学、岩性和矿物组成。根据MC的特点,我们假设了它们的地层设置。与微生物过程相关的MnO含量升高,以及亲生物元素的高浓度,都表明有机质积极参与了微生物沉积物的形成和发育。微生物碳酸盐中碳的同位素组成进一步支持二氧化碳的生物源在这些矿床的形成中起着重要作用。研究表明,晚侏罗世锰矿砾岩经历了强烈的次生蚀变、部分再结晶和钙化作用。在黄铁矿与方解石带接触处,形成了含黄铁矿碎片的等长黄铁矿晶体聚集体。我们认为,Krasnoleninsky拱的Yem-Egovskaya油田微生物碳酸盐中存在溶洞和高储层潜力可能是由于强烈的次生变质作用。
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引用次数: 0
Middle Devonian stromatoporoid-dominated reefs at Maoying, South China: New insights into age, biotic turnover and palaeogeographical model 毛营中泥盆世叠孔虫为主的礁群:时代、生物更替和古地理模式的新认识
IF 2 Pub Date : 2025-11-24 DOI: 10.1016/j.jop.2025.100315
Jia-Yuan Huang , Wen Guo , Yu-Cong Sun , Wen-Kun Qie
Middle Devonian was the time for extensive reefs across South China, but their importance in understanding the development of reef communities was undervalued. This study described the lithological and palaeontological features of the Middle Devonian reef deposits at Maoying Town, Guizhou Province, South China. Two different units are recognised based on five road-cut exposures. The lower unit is characterised by argillaceous limestone, yielding a variety of auto-to autoparabiostromes. The biostromes are dominated by morphologically diverse stromatoporoids, including Gerronostromaria, Salairella, Synthetostroma, and Stachyodes, with subordinate roles of tabulate corals, rugose corals, chaetetids, bryozoans, brachiopods, gastropods, bivalves, and tubeworms. The upper unit consists mainly of parabiostromes, characterised by abundant dendroid and bulbous stromatoporoids (Amphipora, Stachyodes, and Actinostroma), along with leperditicopid ostracods, parathuramminid foraminifers, and calcispheres. The environments of these two units are interpreted to be open marine and back-reef to lagoonal environments, respectively. Newly recognised icriodid and bipennatid conodonts from the lower unit and brachiopod Stringocephalus in the upper unit indicate a Givetian age of the entire succession, pushing back the age of the latter from Frasnian of the previous thought. Comparison with nearby two sections possibly reflects a palaeogeographical turnover from ramp to carbonate platform. This study sheds light on understanding how reef communities changed in relation to environmental conditions in South China during the expansion of global Givetian reefs.
中泥盆世是华南地区广泛存在珊瑚礁的时期,但它们对了解珊瑚礁群落发展的重要性被低估了。本文描述了贵州茂营镇中泥盆统生物礁沉积的岩性和古生物学特征。两个不同的单位被识别基于五个道路切割暴露。较低的单元以泥质石灰岩为特征,产生各种自拟生基质。叠层孔类以Gerronostromaria、Salairella、Synthetostroma和Stachyodes等形态多样的叠层孔类为主,其次为表珊瑚、绢珊瑚、毛纲、苔藓虫、臂足类、腹足类、双壳类和管虫。上单元主要由副孔虫组成,其特征是大量的树突状和球茎状的层孔虫(Amphipora, Stachyodes, Actinostroma),以及麻风类介形虫,副孔虫,有孔虫和石孔虫。这两个单元的环境分别被解释为开阔的海洋环境和礁后到泻湖环境。新近发现的下部单元的石齿形和双鳍形牙形刺和上部单元的腕足动物链头形牙形刺表明整个演替的给定时代,将后者的年龄从先前认为的弗拉斯尼亚时代推后。与附近两个剖面的对比可能反映了从斜坡到碳酸盐岩台地的古地理转换。该研究揭示了在全球吉田礁扩张过程中,中国南方珊瑚礁群落与环境条件的关系。
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引用次数: 0
Palaeogeography and its controls on organic carbon accumulation in the Wufeng–Longmaxi formations of Chongqing, southeastern Sichuan Basin, southwestern China 四川盆地东南部重庆五峰组—龙马溪组古地理特征及其对有机碳成藏的控制作用
IF 2 Pub Date : 2025-11-19 DOI: 10.1016/j.jop.2025.100314
Yan-Wen Shao , Feng-Hua Zhao , Feng-Xian Jin , Zhen-Sheng Shi , Qun Zhao , Shi-Long Kang , Long-Yi Shao
The Upper Ordovician Wufeng Formation and Lower Silurian Longmaxi Formation are important target strata for shale gas exploration in the Sichuan Basin, China. In this paper, the sedimentary facies and palaeogeography of the two formations in Chongqing area have been analyzed, and total organic carbon (TOC) contents are correlated with the sedimentary facies to prospect the favorable areas for shale gas exploration. According to the lithological characteristics and sedimentary structures, five sedimentary facies are identified, i.e., siliceous deep-water shelf, muddy deep-water shelf, calcareous shallow-water shelf, muddy shallow-water shelf, and silty-muddy shallow-water shelf facies, respectively. The palaeogeography reconstruction is based on the lithological distribution in the study area. The lower part of Wufeng Formation was developed with the muddy deep-water shelf, siliceous deep-water shelf, and calcareous shallow-water shelf facies. The Guanyinqiao Member, representing the upper part of Wufeng Formation, was developed with the transition from siliceous deep-water shelf and muddy deep-water shelf facies to a domination of muddy shallow-water shelf and calcareous shallow-water shelf facies, which was deposited during the glacial-induced global regression. The Lower Member of Longmaxi Formation was characterized by the expansion of siliceous deep-water shelf facies and contraction of muddy shallow-water shelf and calcareous shallow-water shelf facies, signifying a rapid sea level rise associated with global warming. The Upper Member of Longmaxi Formation was developed with muddy shallow-water shelf facies, with the expansion of calcareous shallow-water shelf and silty-muddy shallow-water shelf facies. The shales with higher TOC content tend to be developed in the siliceous deep-water shelf and muddy deep-water shelf facies that were distributed in the Nanchuan, Shizhu, Yongchuan, and Wuxi areas. The results of lithofacies palaeogeography reconstruction have a certain significance to predict shale-gas target areas in Wufeng and Longmaxi formations of Chongqing.
四川盆地上奥陶统五峰组和下志留统龙马溪组是页岩气勘探的重要目标层。本文通过对重庆地区两组沉积相及古地理的分析,将总有机碳(TOC)含量与沉积相进行对比,寻找页岩气勘探的有利区域。根据岩性特征和沉积构造,确定了5种沉积相,分别为硅质深水陆架相、泥质深水陆架相、钙质浅水陆架相、泥质浅水陆架相和粉质-泥质浅水陆架相。古地理重建以研究区岩性分布为基础。五峰组下部发育泥质深水陆架、硅质深水陆架和钙质浅水陆架相。观音桥段为五峰组上半段,发育于冰川全球退变时期,由硅质深水陆架和泥质深水陆架相向泥质浅水陆架和钙质浅水陆架相为主的过渡时期。龙马溪组下段以硅质深水陆架相扩张、泥质浅水陆架和钙质浅水陆架相收缩为特征,标志着与全球变暖相关的海平面快速上升。龙马溪组上段发育泥质浅水陆架相,发育钙质浅水陆架相和粉质-泥质浅水陆架相。TOC含量较高的页岩多发育在南川、石柱、永川和无锡地区的硅质深水陆架相和泥质深水陆架相。岩相古地理重建结果对重庆五峰组和龙马溪组页岩气靶区预测具有一定意义。
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引用次数: 0
First record of Araucaria with leafy shoots and reproductive organs from the Lower Cretaceous of NW China and its historical biogeography 中国西北下白垩世带叶芽和生殖器官的木蚶的首次记录及其历史生物地理学
IF 2 Pub Date : 2025-11-11 DOI: 10.1016/j.jop.2025.100310
Ai-Jing Li , Bao-Xia Du , Jing Zhang , Jing Peng , Ming-Chen Zhang , Pei-Hong Jin , Shao-Hua Lin , Yi-Qiao Fu , Jing-Jing Cai
The modern Gondwanan genus, Araucaria, exhibited a worldwide distribution during its early evolution in the late Mesozoic. However, the scarcity of fossil records restricted exploring its early radiation and evolution. A new species, Araucaria gansuensis sp. nov. was described based on well-preserved leafy shoots associated with female cones, deciduous pollen cones and bract-scale complexes from the Lower Cretaceous in Northwest China. Maximum parsimony analysis revealed that the phylogenetic position of A. gansuensis is within the basal clade of Sect. Eutacta. Moreover, palaeobiogeographic analysis suggested that Araucaria possibly originated in the low latitudes of the Pangea and formed differentiation centers in Laurasia (East Asia) and Gondwana (South America) in the Middle Jurassic. Furthermore, with the breakup of Pangea, Araucaria rapidly radiated globally, and exhibited a more extensive distribution in the Northern Hemisphere during the Cretaceous. The discovery of A. gansuensis as a significant representative has unveiled a pathway for the dispersion of Araucaria in East Asia and Europe. Subsequently, Araucaria, which belonged to a more primitive lineage, started declining and facing extinction in the Northern Hemisphere in the Early Paleocene due to factors such as geographic isolation, climatic variations, and expansion and dominance of angiosperms.
现代冈瓦南属(Araucaria)在中生代晚期的早期进化中呈现出世界性分布。然而,化石记录的缺乏限制了对其早期辐射和进化的探索。根据保存完好的带雌球果的叶芽、落叶花粉球果和苞片鳞片复合体,描述了中国西北地区下白垩统的一新种——甘肃Araucaria gansuensis sp. 11 .。最大简约性分析表明,甘肃银杏的系统发育位置在长尾科的基支内。此外,古生物地理分析表明,Araucaria可能起源于泛大陆的低纬度地区,并在中侏罗世形成了东亚Laurasia和南美洲Gondwana的分异中心。此外,随着盘古大陆的分裂,白垩纪Araucaria迅速向全球扩散,在北半球的分布更为广泛。gansuensis的发现作为一个重要的代表,揭示了Araucaria在东亚和欧洲扩散的途径。随后,由于地理隔离、气候变化以及被子植物的扩张和优势等因素,原属较原始谱系的荒木属在北半球的古新世早期开始衰落并面临灭绝。
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引用次数: 0
Organic lithofacies and its reservoir characteristics of lacustrine shales of the Dongyuemiao Member in the Jurassic Ziliujing Formation, eastern Sichuan Basin 川东侏罗系自流井组东月庙段湖相页岩有机岩相及储层特征
IF 2 Pub Date : 2025-11-05 DOI: 10.1016/j.jop.2025.100309
Ming-Yang Wei , Wang Chen , Xing-Zhi Wang , Zhi-Dong Bao , De-Ming Zeng , Jia-Hao Kang , Yang Li , Kai-Ming Liu , Fei Huo
This study investigates the reservoir properties and main controlling factors of different organic lithofacies in the Jurassic Dongyuemiao Formation lacustrine shales, eastern Sichuan Basin. Based on lithofacies classification, the spatial characteristics and physical properties of the reservoirs, along with the primary controlling factors, were analyzed using core observation, scanning electron microscopy (SEM), low-temperature nitrogen adsorption, and other techniques. The results indicate that: 1) In the eastern Sichuan Basin, the Dongyuemiao Member is predominantly composed of clay minerals and quartz, which are the main mineral constituents of the lacustrine shales. Minor amounts of calcite, feldspar, dolomite, pyrite, and rhodochrosite are also present. Four main lithofacies were identified within the study area: argillaceous shale with high-medium TOC (Ⅰ2), mixed shale with low-medium TOC (Ⅱ1), sacrilegious-silt mixed shale with medium-low TOC (Ⅱ2), and argillaceous siltstone with low TOC (Ⅲ2). 2) The shale microstructure is characterized by micropores, primarily comprising intergranular pores between clay minerals and organic-matter pores. Intragranular dissolution pores, notably within shell fragments, are locally developed. Microfractures are mainly observed as intra-layer shale fractures and fractures along the edges of shell fragments. 3) High organic matter abundance (>1 %), high clay mineral content (>40 %), and moderate carbonate mineral content (<10 %) in the shale of the study area contribute to the development of pores. In contrast, high quartz and feldspar mineral content (>50 %) and excessively high (>12 %) or low (<8 %) carbonate mineral content inhibit shale pore development. 4) A comprehensive analysis shows that the argillaceous-silt mixed shale with medium-low TOC (Ⅱ2) is the most favorable lithofacies for reservoir development, followed by argillaceous shale with high-medium TOC (Ⅰ2). The mixed shale with lower-medium TOC (Ⅱ1) is less favorable, and the argillaceous siltstone with low TOC (Ⅲ2) is the poorest. Considering the vertical distribution of lithofacies in the Dongyuemiao Member, it is concluded that the middle-upper part of the Dong 2 submember is the most prospective reservoir interval in the study area.
研究了川东侏罗系东月庙组湖相页岩不同有机岩相储层物性及主控因素。在岩相分类的基础上,利用岩心观察、扫描电镜(SEM)、低温氮吸附等技术,分析了储层空间特征、物性特征及主控因素。结果表明:1)川东地区东月庙段以粘土矿物和石英为主,是湖相页岩的主要矿物成分;少量方解石、长石、白云石、黄铁矿和红锰矿也存在。研究区主要发育4种岩相:高-中TOC泥质页岩(Ⅰ2)、低-中TOC混合页岩(Ⅱ1)、中-低TOC泥质-淤泥质混合页岩(Ⅱ2)和低TOC泥质粉砂岩(Ⅲ2)。2)页岩微观结构以微孔为特征,主要包括黏土矿物与有机质孔隙之间的粒间孔。粒内溶蚀孔,尤其是壳片内溶蚀孔,是局部发育的。微裂缝主要表现为层内页岩裂缝和壳片边缘裂缝。3)研究区页岩有机质丰度高(> 1%),粘土矿物含量高(> 40%),碳酸盐矿物含量适中(< 10%),有利于孔隙发育。石英和长石矿物含量高(50%)和碳酸盐矿物含量过高(12%)或过低(8%)抑制页岩孔隙发育。4)综合分析表明,中低TOC的泥质-粉质混合页岩(Ⅱ2)是最有利于储层发育的岩相,其次是中高TOC的泥质页岩(Ⅰ2)。中低TOC混合页岩(Ⅱ1)较差,低TOC泥质粉砂岩(Ⅲ2)最差。结合东月庙段岩相垂向分布,认为东2亚段中上部是研究区最具发展前景的储层段。
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引用次数: 0
Sedimentology, provenance, and paleoclimate of Jurassic–Cretaceous red beds: Example from the southern front of the Central High Atlas and Northern Preafrican Trough, Morocco 侏罗纪-白垩纪红层沉积学、物源和古气候:以摩洛哥中部高阿特拉斯南锋和北非海槽为例
IF 2 Pub Date : 2025-10-14 DOI: 10.1016/j.jop.2025.100299
Said Adardor , Hicham Nasri , Hamid Haddoumi , Radouan El Bamiki , Rachid Chennouf , Hanane Miri
Five stratigraphic sections from the Aghbalou N'Kerdouss–Tadighoust area were analyzed using integrated petrographic, granulometric, calcimetric, and mineralogical approaches applied to both bulk samples and clay fractions. The findings reveal a transitional depositional environment shaped by a dynamic interplay of continental and restricted marine influences, particularly within the Ifezouane Formation (Member 2), which reflects low-amplitude sea-level oscillations under confined paleoenvironmental conditions. Whole-rock mineralogy is dominated by quartz, K-feldspar, plagioclase, hematite, calcite, dolomite, siderite, and gypsum. The associated clay mineral assemblages comprise illite, kaolinite, smectite, and chlorite, with compositional variability across sections. Illite crystallinity and illite chemistry index data indicate a dual provenance, with sediment sources originating from both the Anti-Atlas and Sahara regions to the south, as well as the Jurassic uplands to the north. These interpretations are supported by petrographic evidence and mineralogical signatures. Furthermore, the mineralogical data suggest that arid to semi-arid climatic conditions and/or tectonic activity played a significant role during deposition. This study demonstrates how the integration of clay mineral signatures with petrography, grain-size distribution, and calcimetric data offers a reliable basis for reconstructing provenance, unraveling paleoenvironmental conditions, and refining palaeogeographic reconstructions of peri-Tethyan basins, while also providing a comparative framework applicable to analogous red bed systems worldwide.
对Aghbalou N 'Kerdouss-Tadighoust地区的5个地层剖面进行了综合岩石学、颗粒学、钙学和矿物学分析,并对大块样品和粘土组分进行了分析。这些发现揭示了一个由大陆和有限海洋影响的动态相互作用形成的过渡性沉积环境,特别是在Ifezouane组(成员2)内,这反映了在受限的古环境条件下的低幅度海平面振荡。全岩矿物学以石英、钾长石、斜长石、赤铁矿、方解石、白云石、菱铁矿和石膏为主。伴生的粘土矿物组合包括伊利石、高岭石、蒙脱石和绿泥石,其成分在剖面上具有可变性。伊利石结晶度和伊利石化学指数数据表明其具有双重物源特征,沉积物源既来自南部的反阿特拉斯和撒哈拉地区,也来自北部的侏罗纪高地。这些解释得到了岩石学证据和矿物学特征的支持。此外,矿物资料表明,干旱至半干旱的气候条件和/或构造活动在沉积过程中起重要作用。本研究展示了粘土矿物特征与岩石学、粒度分布和钙测量数据的整合如何为重建近特提斯盆地的物源、揭示古环境条件和改进古地理重建提供可靠的基础,同时也提供了一个适用于全球类似红层体系的比较框架。
{"title":"Sedimentology, provenance, and paleoclimate of Jurassic–Cretaceous red beds: Example from the southern front of the Central High Atlas and Northern Preafrican Trough, Morocco","authors":"Said Adardor ,&nbsp;Hicham Nasri ,&nbsp;Hamid Haddoumi ,&nbsp;Radouan El Bamiki ,&nbsp;Rachid Chennouf ,&nbsp;Hanane Miri","doi":"10.1016/j.jop.2025.100299","DOIUrl":"10.1016/j.jop.2025.100299","url":null,"abstract":"<div><div>Five stratigraphic sections from the Aghbalou N'Kerdouss–Tadighoust area were analyzed using integrated petrographic, granulometric, calcimetric, and mineralogical approaches applied to both bulk samples and clay fractions. The findings reveal a transitional depositional environment shaped by a dynamic interplay of continental and restricted marine influences, particularly within the Ifezouane Formation (Member 2), which reflects low-amplitude sea-level oscillations under confined paleoenvironmental conditions. Whole-rock mineralogy is dominated by quartz, K-feldspar, plagioclase, hematite, calcite, dolomite, siderite, and gypsum. The associated clay mineral assemblages comprise illite, kaolinite, smectite, and chlorite, with compositional variability across sections. Illite crystallinity and illite chemistry index data indicate a dual provenance, with sediment sources originating from both the Anti-Atlas and Sahara regions to the south, as well as the Jurassic uplands to the north. These interpretations are supported by petrographic evidence and mineralogical signatures. Furthermore, the mineralogical data suggest that arid to semi-arid climatic conditions and/or tectonic activity played a significant role during deposition. This study demonstrates how the integration of clay mineral signatures with petrography, grain-size distribution, and calcimetric data offers a reliable basis for reconstructing provenance, unraveling paleoenvironmental conditions, and refining palaeogeographic reconstructions of peri-Tethyan basins, while also providing a comparative framework applicable to analogous red bed systems worldwide.</div></div>","PeriodicalId":100819,"journal":{"name":"Journal of Palaeogeography","volume":"15 1","pages":"Article 100299"},"PeriodicalIF":2.0,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145363887","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}
引用次数: 0
期刊
Journal of Palaeogeography
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