Journal of Palaeogeography最新文献_第8页

Astronomically-paced lake-level changes on halite deposition during the Paleogene in the Huanggang Basin, East China 黄冈盆地古近系湖泊水位变化对岩盐沉积的影响

IF 2

Journal of Palaeogeography

Pub Date : 2025-07-01 DOI: 10.1016/j.jop.2024.12.008

Cui-Yu Song , Da-Wei Lü , Wen-Tao Chen , Munira Raji , Bin Yang , Zhen-Guo Ning , Lu-Lu Tang , Zhi-Hui Zhang

The formation of halite in continental basins is intimately linked to lake-level changes. Current research has revealed the connection between lake-level variations and astronomical forcing on a million-year scale. Other studies have also highlighted the influence of orbitally-induced climate cycles on halite deposition. However, our understanding of the impact of astronomically-paced lake-level changes on halite formation remains constrained. The Paleogene Dawenkou Formation in the Huanggang Basin of East China provides a continuous salt-bearing sedimentary record to investigate the lake-level changes in halite deposition. Lake-level fluctuations reconstructed by sedimentary noise modeling for the Middle and Upper members of the Dawenkou Formation indicate that the lake-level variations in the Huanggang Basin were linked to astronomical forcing with periods of ∼2.4 Myr, ∼1.2 Myr and/or ∼100 kyr. Our results suggest that astronomical forcing, as a driver of lake-level variations, may have had an impact on halite deposition during the Paleogene. In the initial stage of halite formation within the Middle Member of the Dawenkou Formation, reduced heat and moisture transport during the ∼1.2 Myr obliquity minima resulted in low lake levels in mid-to-high latitudes. The prolonged droughts caused by the low amplitude of ∼2.4 Myr eccentricity created conditions more favorable for the development of thicker layers of halite. Subsequently, in the next halite-forming stage, a larger amplitude of ∼2.4 Myr eccentricity led to a more humid climate. Warm/dry winters and cool summers paced by the ∼100 kyr orbital eccentricity minima resulted in enhanced evaporation, relatively lower lake levels, and thinner halite deposition. Nevertheless, the possible transgressions may have contributed to complicated phase relationship between the lake-level change cycles and orbital cycles. This study offers an opportunity to delve deeper into the mechanism of halite deposition by objectively reconstructing lake levels using sedimentary noise modeling.

陆相盆地中岩盐的形成与湖面变化密切相关。目前的研究已经揭示了一百万年尺度上的湖泊水位变化和天文作用力之间的联系。其他研究也强调了轨道引起的气候循环对岩盐沉积的影响。然而，我们对以天文速度变化的湖泊水位对岩盐形成的影响的理解仍然有限。黄冈盆地古近系大门口组为研究岩盐沉积的湖平面变化提供了连续的含盐沉积记录。通过沉积噪声模拟重建的大汶口组中上段湖泊水位波动表明，黄冈盆地的湖泊水位变化与天文强迫有关，周期为~ 2.4 Myr、~ 1.2 Myr和/或~ 100 kyr。我们的研究结果表明，天文强迫作为湖泊水位变化的驱动因素，可能对古近纪期间的岩盐沉积产生了影响。在大汶口组中段岩盐形成初期，在倾角最小值~ 1.2 Myr期间，热量和水分输送减少，导致中高纬度湖泊水位低。由~ 2.4 Myr偏心率的低振幅引起的长期干旱为较厚岩盐层的发育创造了更有利的条件。随后，在下一个岩盐形成阶段，较大的~ 2.4 Myr偏心率振幅导致气候更加湿润。温暖/干燥的冬季和凉爽的夏季以~ 100 kyr的轨道偏心率最小值为速度，导致蒸发增强，湖泊水位相对较低，岩盐沉积较薄。然而，可能的海侵可能导致了湖平面变化旋回与轨道旋回之间复杂的相位关系。本研究利用沉积噪声模型客观地重建湖泊水位，为深入研究岩盐沉积机制提供了契机。

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引用次数: 0

Systematic palaeontology and biostratigraphy of early Oligocene larger benthic foraminifera, offshore, southern Iran (Asmari Formation) 伊朗南部近海早渐新世（Asmari组）大型底栖有孔虫系统古生物学与生物地层学

IF 2

Journal of Palaeogeography

Pub Date : 2025-07-01 DOI: 10.1016/j.jop.2024.08.013

Mohsen Yazdi-Moghadam , Mehdi Sarfi , Mehrdad Naghusi , Mohammad Sharifi , Reza Aharipour , Houshang Khairy

The biostratigraphic aspects of the lower Oligocene carbonates of the Asmari Formation, offshore, southern Iran were analyzed, providing a high-resolution dating based on recovered larger benthic foraminifera. As a part of the Tethyan Seaway, the Asmari Formation is located between the Western and Eastern Tethys Oceans. The fauna is dominated by both hyaline perforated and porcelaneous forms, including Nummulites fichteli, Operculina complanata, Eulepidina formosoides, Austrotrillina paucialveolata, and Peneroplis thomasi. Data from the Asmari Formation show a high similarity to occurrences from the Western Tethys. The co-existence of Nummulites fichteli and Eulepidina formosoides indicates SBZ 22A Subzone referring to a short time span restricted to late Rupelian.

对伊朗南部近海Asmari组下渐新世碳酸盐岩的生物地层进行了分析，并根据回收的大型底栖有孔虫提供了高分辨率的年代测定。作为特提斯海道的一部分，阿斯马里地层位于特提斯西部和东部海洋之间。区系以透明穿孔型和瓷状两种类型为主，包括麻麻属（Nummulites fichteli）、平皮属（Operculina complanata）、formosoides、Austrotrillina paucialveolata和Peneroplis thomasi。来自阿斯马里组的数据显示，与西特提斯的事件高度相似。麻麻属（Nummulites fichteli）与formosoides属（Eulepidina formosoides）共存，属于SBZ 22A亚区，时间跨度较短，仅局限于鲁伯利晚期。

引用次数: 0

Cyclic gravity flow deposits constrained by alternating dry/wet climates in a middle‒late Eocene saline lake, Jianghan Basin, Hubei Province, China 湖北江汉盆地始新世中晚期干湿交替气候约束下的旋回重力流沉积

IF 2

Journal of Palaeogeography

Pub Date : 2025-07-01 DOI: 10.1016/j.jop.2025.100257

Tao-Yuan Ge , Xiang-Xin Kong , Zai-Xing Jiang , Shi-Qiang Wu , Mathieu Schuster , Guilherme Bozetti

Lacustrine sediments serve as valuable archives of extreme events and past environmental changes. However, the formation mechanisms and distribution patterns of gravity flow deposits in inland hypersaline lakes under climatic controls remain underexplored. In the Eocene Jianghan Basin, rhythmic strata influenced by climatic cycles provide a unique opportunity to investigate the relationship between gravity flow deposits and paleoclimate. According to core descriptions, thin section analysis, logging data, and grain size analysis, seven lithofacies and four lithofacies associations related to gravity flow deposits were identified. Frequent turbidity flows, primarily flood-induced gravity flows, are widely distributed in the saline lake. Proximal gravity flow deposits are characterized by thick, massive sandstones with minimal mud debris, occasionally featuring deformed lamination and scoured bases. Distal gravity flow deposits comprise clast-bearing massive sandstones, planar laminated sandstones, and graded siltstones. Paleoclimate analysis, based on trace elements and rock salt thickness, reveals a strong linkage between gravity flow deposits and climatic cycles. Correlations were established by systematically identifying short-term base-level cycles, which were subsequently grouped into medium-term base-level cycles through stacking pattern analysis. Short-term base-level changes, corresponding to stable climatic cycles, are marked by rhythmic salt layers. In contrast, medium-term base-level cycles, controlled by orbital periods, govern the deposition of gravity flow deposits. Under arid climatic conditions, reduced vegetation coverage and pronounced temperature variations lead to intensified erosion and increased suspended particle concentration. The deposition of sandstone layers is more substantial, and the frequency of turbidity flows is significantly higher under arid climatic conditions compared to humid climatic conditions. This research highlights how climatic cycles influence gravity flow deposits in hypersaline lake environments.

湖泊沉积物是极端事件和过去环境变化的宝贵档案。然而，气候控制下内陆高咸水湖重力流沉积的形成机制和分布模式尚不清楚。江汉盆地始新世受气候旋回影响的韵律地层为研究重力流沉积与古气候的关系提供了独特的机会。根据岩心描述、薄片分析、测井资料和粒度分析，确定了与重力流沉积有关的7个岩相和4个岩相组合。频繁的浊流，主要是洪水引起的重力流，在盐湖中广泛分布。近端重力流沉积的特征是厚而块状的砂岩，泥屑很少，偶尔也有变形的层状和冲刷的基底。远端重力流沉积包括含碎屑块状砂岩、平面层状砂岩和级配粉砂岩。基于微量元素和岩盐厚度的古气候分析揭示了重力流沉积与气候旋回之间的强烈联系。通过系统地识别短期基础水平周期，建立相关性，随后通过堆叠模式分析将其分组为中期基础水平周期。与稳定的气候周期相对应的短期基准面变化以有节奏的盐层为标志。相反，中期基准面旋回受轨道周期控制，控制重力流沉积。在干旱气候条件下，植被覆盖度的减少和明显的温度变化导致侵蚀加剧和悬浮颗粒浓度的增加。与湿润气候条件相比，干旱气候条件下砂岩层的沉积更加丰富，浊度流动的频率明显更高。这项研究强调了气候循环如何影响高盐湖环境中的重力流沉积。

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引用次数: 0

Fossil evidence and ecological niche modelling reveal trait evolution and biogeography of the Ilex cornuta lineage 化石证据和生态位模型揭示了冬青世系的特征演化和生物地理学

IF 2

Journal of Palaeogeography

Pub Date : 2025-07-01 DOI: 10.1016/j.jop.2025.02.003

Xue-Yan Li , Gi-Soo Nam , Shu-Feng Li , Anna Averyanova , Yi Yang , Ma-Byong Yoon , Lin-Bo Jia

Naturally occurring in the subtropical regions of China to Korea, Chinese Holly (Ilex cornuta Lindl. & Paxton, Aquifoliaceae), is widely cultivated as an ornamental plant. However, the origins of the phenotypical diversity of the species as well as its geographical history remain elusive. Here we report 50 exceptionally well-preserved fossil leaves of the I. cornuta lineage from the middle Miocene of South Korea. These fossils showcase delicate details, encompassing both adaxial and abaxial surfaces, as well as primary to quinternary venation patterns. The varied leaf morphologies, ranging from three to seven spines, demonstrate that these leaf morphologies of I. cornuta were established by the middle Miocene. Furthermore, fossil discoveries from the middle and late Miocene of Korea and China, coupled with the enduring presence of highly suitable habitats in Asia since the late Paleogene, suggest a longstanding persistence of the I. cornuta lineage in this region. The identification of closely related fossils from the Miocene to Pliocene of Europe implies potential floristic interchange between the continents, facilitated by the regression of the Turgai Strait in the Paleogene. This is consistent with the broad suitable habitat of the lineage, which once spanned Europe and Asia from the late Eocene to early Oligocene. Our study provides an example for integrating fossil records with ecological niche modelling to elucidate the biogeographical history of plants.

中国冬青（Ilex cornuta Lindl）天然生长于中国至朝鲜的亚热带地区。,水仙花属，是一种广泛种植的观赏植物。然而，物种表型多样性的起源及其地理历史仍然难以捉摸。在这里，我们报告了50个保存非常完好的来自韩国中新世中期的I. cornuta谱系的化石叶子。这些化石展示了微妙的细节，包括正面和背面，以及初级到第四内脉模式。不同的叶片形态，从3到7刺不等，表明这些叶片形态是在中新世中期建立的。此外，来自韩国和中国中新世中晚期的化石发现，加上自古近纪晚期以来亚洲高度适宜的栖息地的长期存在，表明在这一地区长期存在着角犀世系。从欧洲中新世到上新世密切相关的化石的鉴定表明，古近纪图尔盖海峡的退缩促进了大陆间潜在的植物区系交换。这与该谱系的广泛适宜栖息地相一致，该谱系曾在始新世晚期至渐新世早期跨越欧洲和亚洲。本研究为将化石记录与生态位模型相结合来阐明植物的生物地理历史提供了一个范例。

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引用次数: 0

Hydrocarbon signatures as a tool for unraveling the stratigraphic problem for Upper Cretaceous–Paleogene sediments from Internal Dinarides, Serbia 油气特征作为揭示塞尔维亚内Dinarides上白垩统-古近系沉积物地层问题的工具

IF 2

Journal of Palaeogeography

Pub Date : 2025-07-01 DOI: 10.1016/j.jop.2025.100260

Ivana Jovanić , Aleksandra Šajnović , Bojan Glavaš-Trbić , Sanja Stojadinović , Nikola Burazer , Branimir Jovančićević

Inorganic and organic geochemical analyses, assisted by micropaleontological investigations, were performed on the Paskovac sediments to differentiate the Cretaceous and Paleogene deposits in Internal Dinarides region. Owning to the presence of fossil assemblages in the in Upper Cretaceous sediments and their scarcity in the Paleogene siliciclastic sediments, the entire Paskovac area was fundamentally incorrectly classified as the Campanian–Maastrichtian. Besides, the Paskovac sedimentary sequence was formed as a consequence of the uppermost Cretaceous–Paleogene tectonic shortening of the Dinarides, during which the Maastrichtian sediments were re-deposited within the Paleogene sequence from the underlying Maastrichtian sediments. Therefore, this study employed thin-section microscopy, atomic absorption spectrometry (AAS), and gas chromatography–mass spectrometry (GC–MS) techniques to closely inspect 27 samples from the Paskovac drillhole. The results revealed a clear division of the samples into two groups based on their geochemical similarities. One group marked as Paleogene clastic sediments characterizes the highest content of terrigenous elements, namely SiO₂ (49.49 %–62.22 %), Al₂O₃ (16.18 %–21.75 %), Fe₂O₃ (3.41 %–6.67 %), TiO₂ (0.63 %–0.80 %), along with sulfur content (2.33 %–2.80 %). The organic matter is rich in odd long-chain n-alkanes, C₂₉ regular sterane (>60 %), benzohopanes, retene, cadalene, and benzo[b]naphthofurans, suggesting predominately terrestrial biomass deposited under suboxic–oxic conditions. Another group, represented by carbonates (CaO up to 51.02 %), contains Maastrichtian assemblages (e.g., Siderolites calcitrapoides), indicating shallow-marine depositional settings. Short-chain even n-alkanes, branched alkanes (e.g., 5,5-diethylalkanes), and C₂₇ regular sterane suggest the presence of biodegraded mixed algal/microbial biomass.

对Paskovac沉积物进行了无机和有机地球化学分析，并结合微古生物学调查，对内迪纳里德地区白垩系和古近系沉积物进行了区分。由于在上白垩统沉积物中存在化石组合，而在古近系硅屑沉积层中缺乏化石组合，整个Paskovac地区从根本上被错误地划分为坎帕尼亚-马斯特里赫特地区。此外，Paskovac沉积序列的形成是上白垩纪-古近纪Dinarides构造缩短的结果，在此期间，马斯特里赫特沉积物从下伏的马斯特里赫特沉积物中重新沉积到古近纪序列中。因此，本研究采用薄层显微镜、原子吸收光谱法（AAS）和气相色谱-质谱法（GC-MS）技术对来自Paskovac钻孔的27个样品进行了仔细检查。结果显示，根据其地球化学相似性，样品可明确分为两组。古近系碎屑沉积物中陆源元素含量最高，分别为SiO2（49.49% ~ 62.22%）、Al2O3（16.18% ~ 21.75%）、Fe2O3（3.41% ~ 6.67%）、TiO2（0.63% ~ 0.80%）和硫含量（2.33% ~ 2.80%）。有机质中含有丰富的奇长链正构烷烃、C29正构甾烷（占60%）、苯并藿烷、网烯、邻苯二烯和苯并[b]萘呋喃，表明主要是在亚氧条件下沉积的陆生生物质。另一组以碳酸盐岩（CaO含量高达51.02%）为代表，含有马斯特里赫特组合（如Siderolites calcitrapoides），表明浅海沉积背景。短链均匀正构烷烃、支链烷烃（如5,5-二乙基烷烃）和C27规则甾烷表明存在生物降解的混合藻/微生物生物量。

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引用次数: 0

Unravelling the Pleistocene climatic evolution in the Siwaliks: implications for hominin settlement in the upper Soan Valley, Pakistan 揭开siwalik地区更新世气候演化：对巴基斯坦苏安河谷上游人类定居的启示

Journal of Palaeogeography

Pub Date : 2025-07-01 DOI: 10.1016/j.jop.2025.100262

Nadir Fawad , Dai-Du Fan , Tai-Xun Liu , Muhammad Kamran , Qazi Adnan Ahmed

Since the early Pleistocene, climatic variability has profoundly influenced population dynamics, including the migration of hominins into and out of Africa. In South Asia, Quaternary sediments, particularly those found in the Siwaliks, provide a valuable record of climatic changes relevant to hominin habitation. While the upper Soan Valley in Pakistan has been extensively studied for evidence of hominin to modern human activities, the associated environmental and climatic changes remain underexplored. This study aims to elucidate the climatic evolution of the Quaternary sediments in the Riwat area, with the primary objective of reconstructing the environmental conditions that facilitated long-term hominin settlement and survival. To address this knowledge gap, we analyzed the geochemistry and clay mineralogy of 46 sediment samples utilizing spectroscopy and X-ray diffractometry (XRD), focusing on the Plio-Quaternary period. Our findings reveal three distinct climatic stages. The first stage (Stage I), was characterized by cold conditions during the Pliocene, and was further divided into semi-arid to semi-humid substages based on C-values. This was followed by a cold to humid climatic stage (Stage II) during the early to middle Pleistocene, marked by moderate to high chemical weathering, which was also categorized into semi-arid to semi-humid substages. Within Stage II, a warm and humid phase was inferred during the early to middle Pleistocene, culminating in the coldest and most arid conditions of Stage III during the late Pleistocene to Holocene. The climatic changes observed are indicative of the uplift of the Himalayan-Tibetan Plateau and the influence of the southwestern monsoon on the Indian subcontinent. Moderate to intense monsoonal activity characterized the early to middle Pleistocene, creating conditions conducive to early hominin settlement and adaptation due to the availability of resources. Conversely, environmental conditions during periods of weakened monsoons exhibited an arid climate from the late Pleistocene to Holocene (corresponding to MIS 1-4 in oceanic records). This study enhances our understanding of hominin-climate interactions and has implications for the role of climate in shaping diverse hominin habitation patterns, both globally (out of Africa) and regionally (South Asian) contexts.

自更新世早期以来，气候变化深刻地影响了人口动态，包括人类进出非洲的迁徙。在南亚，第四纪沉积物，特别是在siwalik发现的沉积物，提供了与人类居住有关的气候变化的宝贵记录。尽管人们已经对巴基斯坦上索安河谷进行了广泛的研究，以寻找古人类到现代人类活动的证据，但相关的环境和气候变化仍未得到充分探索。本研究旨在阐明里瓦特地区第四纪沉积物的气候演变，以重建人类长期定居和生存的环境条件为主要目的。为了解决这一知识空白，我们利用光谱学和x射线衍射（XRD）分析了46个沉积物样品的地球化学和粘土矿物学，重点分析了上新纪-第四纪。我们的发现揭示了三个不同的气候阶段。第一阶段（第一阶段）以上新世的寒冷环境为特征，根据c值进一步划分为半干旱至半湿润亚阶段。更新世早期至中更新世为寒湿气候阶段（II期），以中度至高度化学风化为标志，也分为半干旱至半湿润亚阶段。第二阶段为更新世早期至中期的温暖湿润阶段，第三阶段为更新世晚期至全新世的最冷、最干旱阶段。观测到的气候变化表明喜马拉雅-青藏高原的隆升和西南季风对印度次大陆的影响。早更新世至中更新世具有中度至强烈的季风活动特征，由于资源的可用性，创造了有利于早期人类定居和适应的条件。相反，从晚更新世到全新世，弱季风时期的环境条件表现为干旱气候（对应于海洋记录的MIS 1-4）。这项研究增强了我们对人类与气候相互作用的理解，并对气候在塑造全球（非洲以外）和区域（南亚）人类居住模式中的作用产生了影响。

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引用次数: 0

Sedimentary architecture characterization by combining well logs and seismic data in river-dominated delta reservoirs: the Pearl River Mouth Basin, South China Sea 南海珠江口盆地河控三角洲储层测井与地震资料相结合的沉积构型表征

IF 2

Journal of Palaeogeography

Pub Date : 2025-07-01 DOI: 10.1016/j.jop.2025.03.004

Hong-Hui Li , Da-Li Yue , Wei Li , Ling-Ling Dan , Yuan Liu , Wu-Rong Wang , Ke-Yu Ren , Ling Tan

In offshore fields with limited well data, intricate geological configurations, and high reservoir heterogeneity, the accurate prediction of sand body distribution and characterization of sedimentary architecture pose significant challenges due to inherent geological uncertainties and data limitations. This study employs a comprehensive approach integrating three key methods to enhance prediction accuracy: (i) fusion of spectral-decomposed seismic attributes, (ii) seismic attribute fusion of target and neighboring zones, and (iii) colored seismic inversion. The first method leverages seismic information across various frequencies, yielding reliable results for sand bodies of different thicknesses. The second method mitigates the impact of seismic responses from adjacent zones on sand body predictions, making it particularly suitable for target intervals where neighboring zones significantly influence the seismic response. The third one, colored seismic inversion enhances the prediction of vertical distribution and the stacking relationships of sand bodies. These methods have been applied in an oilfield in the Pearl River Mouth Basin, southern China. Consequently, the sedimentary architecture of a braided river delta reservoir is successfully characterized, leading to the identification of four distributary channels within a depositional Zone 1 of the Zhujiang Formation. Additionally, a comprehensive workflow integrating well logs, seismic data, and depositional models significantly improves predictions of sand body distribution and sedimentary architecture in complex geological settings, providing critical geological insights for optimizing subsequent oilfield development strategies.

在钻井数据有限、地质构造复杂、储层非均质性高的海上油田，由于固有的地质不确定性和数据限制，砂体分布的准确预测和沉积构型的表征面临着巨大的挑战。为了提高预测精度，本研究采用了三种关键方法(1)光谱分解地震属性融合、(2)目标区与邻区地震属性融合、(3)彩色地震反演的综合方法。第一种方法利用不同频率的地震信息，对不同厚度的砂体产生可靠的结果。第二种方法减轻了相邻带地震反应对砂体预测的影响，特别适用于相邻带对地震反应影响较大的目标层段。三是彩色地震反演增强了砂体垂向分布和叠加关系的预测能力。该方法已在珠江口盆地某油田得到应用。结果表明，辫状河三角洲储层的沉积构型得到了成功的表征，并在珠江组沉积1区内识别出了4条分流河道。此外，集成了测井、地震数据和沉积模型的综合工作流程显著改善了复杂地质环境下砂体分布和沉积结构的预测，为优化后续油田开发策略提供了关键的地质见解。

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引用次数: 0

The significance of benthic ecospace expansion following the ROECE at the Cambrian Series 2–Miaolingian boundary, western Henan Province, central China 豫西寒武系—苗岭界ROECE后底栖生态空间扩展的意义

IF 2

Journal of Palaeogeography

Pub Date : 2025-07-01 DOI: 10.1016/j.jop.2025.100256

Da Li, Jian Fu, Yong-An Qi, Xi-Tong He, Man Li, Fu-Qiang Guo

The transition period from the Cambrian Series 2 to Miaolingian was a pivotal juncture in Earth's history, marking the onset of significant shifts in biodiversity and biomass dynamics during the Phanerozoic. Concurrently, profound transformations occurred in the alteration of sedimentary deposits by trace makers, reshaping benthic ecological spaces. This study employs ichnological and ecological methodologies to construct a comprehensive three-dimensional spatial model for ecospace occupation and ecosystem engineering within the Mantou Formation in the western Henan Province, focusing on the transition between the Cambrian Series 2 and Miaolingian. A meticulous statistical analysis of 22 ichnogenera and 32 ichnospecies in the Mantou Formation revealed nuanced variations, such as a decrease in the proportion of predatory organisms in the lower part of Member 2 of the Mantou Formation and a corresponding increase in the upper part. Simultaneously, non-selective deposit-feeding animals exhibit an ascending trend in the lower part of Member 2 and a descending trend in the upper part of Member 2.

In terms of sediment bioturbation, the lower part of Member 2 is characterized by the exclusive presence of biodiffusors and conveyors, whereas regenerators make their appearance in the upper part of Member 2. Affected by the Redlichiid–Olenellid Extinction Carbon isotope Excursion (ROECE) event, metazoans experienced a shift in control dynamics, with microbial mats becoming dominant. Biological activities became intricately intertwined with microbial mats. In the upper part of Member 2, metazoans started recovering, concomitant with the emergence of Thalassinoides and Treptichnus substantially boasting ecosystem engineering impact (EEI) values. These trace makers rapidly amplified the depth and extent of sediment disturbance, giving rise to a profusion of novel ecological niches and catalyzing the transformation of builder functional groups.

从寒武纪二系到苗岭期的过渡时期是地球历史上的一个关键时期，标志着显生宙生物多样性和生物量动态的重大转变。与此同时，痕迹制造者对沉积物的改造也发生了深刻的变化，重塑了底栖生态空间。本文采用技术和生态学方法，以寒武纪二系与苗岭期过渡带为研究对象，构建了豫西地区满头组生态空间占用与生态系统工程的三维综合空间模型。通过对曼头组22个鱼属和32个鱼种的精细统计分析，发现了曼头组二段下部捕食生物比例下降，上部捕食生物比例相应增加的细微变化。同时，非选择性沉积饲养动物在2段下部呈上升趋势，在2段上部呈下降趋势。在沉积物生物扰动方面，第二段下部的特征是生物扩散器和传送带的专属存在，而再生器则出现在第二段上部。受Redlichiid-Olenellid灭绝碳同位素偏移（ROECE）事件的影响，后生动物经历了控制动力学的转变，微生物席成为主导。生物活动与微生物席错综复杂地交织在一起。在成员2的上部，后生动物开始恢复，同时出现了具有生态系统工程影响（EEI）值的Thalassinoides和Treptichnus。这些痕迹制造者迅速扩大了沉积物扰动的深度和程度，产生了大量新的生态位，并催化了建造者功能群的转变。

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引用次数: 0

Sedimentology, sequence stratigraphy and geochemical reappraisal of the Mesoproterozoic Rampur Shale, Vindhyan Basin, India: Implications for paleoenvironment and basin evolution 印度Vindhyan盆地中元古代Rampur页岩沉积学、层序地层学和地球化学重新评价：古环境和盆地演化意义

IF 2

Journal of Palaeogeography

Pub Date : 2025-07-01 DOI: 10.1016/j.jop.2025.100259

Indrani Mondal , Adrita Choudhuri , Tathagata Roy Choudhury , Shilpa Srimani , Amlan Koner , Sunipa Mandal , Subir Sarkar

This paper investigates the sedimentology and geochemistry of the black shale deposit of the Rampur Shale Member and interprets the depositional environment, the provenance of the sediments, and the paleoclimatic and paleo-redox conditions to elucidate the evolution history of the Vindhyan Basin in central India during the Mesoproterozoic time. The Rampur Shale Member consists of five facies, representing a fining-upward succession dominated by a coarse-grained sandstone-siltstone alternation at the basal part with an increasing shale content towards the top, culminating into a black shale deposit. Process-based facies analysis documents the shift in the depositional environment from the lower shoreface to the outer part of the continental shelf, suggesting a basin-wide marine transgression which resulted in the deposition of the black shale within the maximum flooding zone (MFZ). Abundant organic matter, with δ¹³C_org values ranging between −25‰ and −34.30‰, preserved in the form of the crinkly laminated, lensoidal, and spheroidal-shaped microbial mat growth on the sediment surface contributes to the characteristic dark hue of the black shale, which is further supplemented by the high TOC (Total Organic Carbon) content of the black shale. Several geochemical proxies suggest that the sediments were sourced predominantly from felsic igneous provinces; however, increased contributions from mafic sources were recorded during the later stages of deposition. The weathering intensity was high, and the black shale was deposited under humid climatic conditions. The paleoredox proxies suggest predominantly anoxic depositional conditions, most likely forming via organic matter degradation. The paleosalinity remained low due to the epicontinental nature of the basin, possibly as a consequence of dilution by freshwater influx from the basin margin. The trace metal proxies suggest the prevalence of upwelling conditions, perhaps resulting in the increased bio-productivity during the black shale deposition. Numerous slide planes at successive intervals bear the signature of basin subsidence and deepening, facilitating basin-wide black shale formation.

本文通过对Rampur页岩段黑色页岩沉积的沉积学和地球化学研究，对其沉积环境、物源、古气候和古氧化还原条件进行了解释，阐明了印度中部Vindhyan盆地中元古代的演化历史。Rampur页岩段由5个相组成，代表了一个以基底为粗粒砂岩-粉砂岩交替为主的向上细化序列，上部页岩含量增加，最终形成黑色页岩矿床。基于过程相分析的沉积环境从下滨面向陆架外半部转移，表明在最大泛洪带（MFZ）内沉积黑色页岩的是一次全盆地海侵。丰富的有机质δ13Corg值在−25‰~−34.30‰之间，以褶皱层状、透镜状、球状微生物席生长的形式保存在沉积物表面，形成了黑色页岩特有的深色色调，并补充了黑色页岩较高的总有机碳含量。地球化学指标表明，沉积物主要来自长英质火成岩省；然而，在沉积后期，镁质来源的贡献有所增加。风化强度大，黑色页岩是在潮湿气候条件下沉积的。古氧化还原指标表明主要是缺氧沉积条件，极有可能是有机质降解形成的。由于盆地的陆表性，古盐度保持在较低水平，这可能是盆地边缘淡水流入稀释的结果。微量金属指标表明，上升流条件的普遍存在，可能导致黑色页岩沉积期间生物生产力的提高。连续间隔的众多滑动面具有盆地沉降和加深的特征，有利于全盆地黑色页岩的形成。

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引用次数: 0

Provenance of the Devonian Liuling Group sandstones: Constraints on Paleozoic North–South China Block tectonics 泥盆系柳岭群砂岩物源：对古生代中国南北地块构造的制约

Journal of Palaeogeography

Pub Date : 2025-07-01 DOI: 10.1016/j.jop.2025.100264

Lei-Gang Zhang, Hong-Jun Qu, Peng Li

The Devonian Liuling Group (DLLG) and its surrounding strata provide massive information about the Paleozoic subduction–suture–extension process of the North China Block (NCB) and South China Block (SCB). Systematic field-based sedimentology, sandstone modal composition, whole-rock elemental composition, and detrital zircon U–Pb dating were employed. The sedimentary sequence of DLLG shows that the water depth deepened and then shallowed, which is characteristic of an extensional basin. Analysis of the tectonic setting and geochronology revealed that the fore-arc sedimentary system (FAS) and DLLG were sourced from the North Qinling Belt (NQB) and NCB. An age population with a single peak at 420 Ma from the FAS suggests that the island arc existed at 420 Ma, indicating that the subduction of the Shangdan Ocean did not finish until the late Silurian. The DLLG deposits were mainly from basement material of the NQB, indicating that the Shangdan Ocean closed before the Middle Devonian, which implies that the NQB and South Qinling Belt (SQB) were spliced during the Early Devonian. This rapid transition from subduction to extension and the absence of molasse hint that no full orogeny occurred during the suture process and that the DLLG formed in a post-suture extensional rift basin.

泥盆系柳岭群（DLLG）及其周围地层为华北地块（NCB）和华南地块（SCB）古生代俯冲-缝合-伸展过程提供了大量信息。采用系统的野外沉积学、砂岩模态组成、全岩元素组成和碎屑锆石U-Pb定年。DLLG沉积序列表现为先深后浅，具有拉张盆地的特征。构造环境和年代学分析表明，弧前沉积体系（FAS）和DLLG来源于北秦岭带（NQB）和北秦岭带（NCB）。FAS在420 Ma有一个单峰的年龄群，表明岛弧存在于420 Ma，表明上丹洋的俯冲直到志留纪晚期才结束。DLLG沉积主要来自于北秦岭带的基底物质，表明上丹洋在中泥盆世之前闭合，表明北秦岭带与南秦岭带在早泥盆世就发生了拼接。这种从俯冲到伸展的快速转变和无糖料的存在暗示了在缝合过程中未发生完全的造山运动，表明大陆块构造是在缝合后的伸展裂谷盆地中形成的。

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引用次数: 0