Journal of Palaeogeography最新文献_第6页

New perspectives on the paleogeographic context of the Late Paleozoic Ice Age in Southwest Gondwana: U–Pb ages and sedimentary provenance data from the Paganzo Basin, Argentina 冈瓦纳西南部晚古生代冰期古地理背景的新视角：阿根廷Paganzo盆地的U-Pb年龄和沉积物源数据

IF 2

Journal of Palaeogeography

Pub Date : 2025-07-15 DOI: 10.1016/j.jop.2025.100274

Julián D. Rolan , Jonatan A. Arnol , Francisco I. Lugo , Norberto J. Uriz , Andrea R. Bidone , Carlos A. Cingolani , Miguel A.S. Basei , Maximiliano Naipauer

This study presents the first detrital zircon U–Pb analysis alongside new petrographic data from the Jejenes Formation (Serpukhovian–Bashkirian), located on the southern margin of the Paganzo Basin, Argentina in Southwest Gondwana. The results were compared with previously published data from other synchronously deposited units to the north (Guandacol Formation) and northeast (Malanzán Formation). Notably, glacigenic deposits are present in both the Guandacol and Jejenes formations but absent in the Malanzán Formation. A sedimentary provenance analysis was conducted for the three units, highlighting similarities and differences among the depocenters, allowing for the reconstruction of the paleogeographic and topographic landscape of the Paganzo Basin during the Serpukhovian–Bashkirian time. The comparative analysis supports the idea of disconnection and isolation among the three depocenters with each unit recording predominantly proximal sources and the recycling of pre-Carboniferous substrate. Although certain similarities exist in the age distribution of the detrital zircon grains recorded for the Malanzán and Guandacol formations, this does not imply that the depocenters were connected or fed by the same source area. Instead, these successions were likely sourced from rocks with a similar geological history, resulting in comparable age distributions due to sediment recycling. Thus, the results support a conservative approach when estimating sedimentary provenance in ancient glacigenic deposits, emphasizing the need to evaluate local sediment sources. The absence of glacigenic deposits in the Malanzán Formation could be linked to a lower topography, linked to distinct tectonic histories in the Pie de Palo, Valle Fértil, and Chepes–Malanzán ranges, underscoring the role of tectonic inheritance in the distribution of glacial centers during the Late Paleozoic Ice Age.

本研究首次对碎屑锆石U-Pb进行了分析，并对位于阿根廷冈瓦纳西南部Paganzo盆地南缘的Jejenes组（Serpukhovian-Bashkirian）进行了新的岩石学分析。研究结果与北部（guanandacol组）和东北部（Malanzán组）其他同期沉积单元的数据进行了比较。值得注意的是，在Guandacol组和Jejenes组中都有冰川沉积，但在Malanzán组中没有。对三个单元进行了沉积物源分析，突出了沉积中心之间的相似性和差异性，从而重建了Serpukhovian-Bashkirian时期Paganzo盆地的古地理和地形景观。对比分析支持了三个沉积中心之间的分离和隔离的观点，每个单元主要记录近端物源和前石炭系底物的再循环。虽然Malanzán组和关达科尔组的碎屑锆石颗粒年龄分布存在一定的相似性，但这并不意味着两个沉积中心是由同一源区连接或形成的。相反，这些序列可能来自具有相似地质历史的岩石，由于沉积物循环，导致年龄分布相似。因此，在估计古冰川沉积物源时，结果支持保守的方法，强调需要评估当地的沉积物来源。Malanzán组没有冰川沉积可能与较低的地形有关，与Pie de Palo、Valle fsamritil和Chepes-Malanzán范围的不同构造历史有关，强调了构造继承在晚古生代冰期冰川中心分布中的作用。

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引用次数: 0

Paleoenvironmental reconstruction and sequence biostratigraphy of Miocene transgressive–regressive sedimentary succession in the northern JDA, northern Malay Basin 马来盆地北部JDA北部中新世海退沉积演替古环境重建及层序生物地层学研究

IF 2

Journal of Palaeogeography

Pub Date : 2025-07-14 DOI: 10.1016/j.jop.2025.100273

Fatin Nur Adilah Md Idris , Khairul Azlan Mustapha , Fatin Izzati Mihnat , Zainey Konjing

The northern sector of the Malay Basin has long been underrepresented, leaving a gap in the understanding of its paleoenvironmental evolution. In addressing this gap, detailed biostratigraphic analysis based on palynology and foraminifera from two wells, i.e., Tj-1 and Tp-1, has been conducted to reconstruct the paleoenvironment during the Miocene age. The factors influencing their distribution were analyzed using a sequence biostratigraphic approach, complemented by environmental parameters such as grain size and organic matter content, supported by seismic and gamma ray logs. The findings reveal significant differences in the faunal distribution of the inner shelf and delta front between the two studied wells. The inner shelf in Tj-1 well is dominated by Asterorotalia pulchella and the accessory species Pseudorotalia schroeteriana. Whereas Tp-1 well, is dominated by Pseudorotalia schroeteriana, but Asterorotalia pulchella is absent. For delta front species, Bigenerina sp. and Reophax sp. are found throughout Tp-1 well. However, in Tj-1 well, the dominant assemblages are Bigenerina sp. and Miliammina sp. during Serravallian to Tortonian, and Cavarotalia annectens from Tortonian to Messinian. Furthermore, our study identifies a major transgressive–regressive (T–R) event during Langhian to Serravallian period, inferred from stratigraphic dating using the standard palynological zonation of Malay Basin (‘PR’ zone) with the age according to VIM (Vietnam–Indonesia–Malaysia) and SEA (Southeast Asia) cycles, which also highlights unconformities. This suggests that tectonic events have led to distinct fauna provinces within the Miocene biostratigraphic assemblages.

长期以来，对马来盆地北部地区的研究较少，对其古环境演化的认识存在空白。为了弥补这一空白，利用Tj-1井和Tp-1井的孢粉学和有孔虫进行了详细的生物地层分析，重建了中新世的古环境。采用层序生物地层学方法，辅以粒度和有机质含量等环境参数，并以地震和伽马测井资料为支撑，分析了影响其分布的因素。研究结果表明，在两个研究井之间，内陆架和三角洲前缘的动物分布存在显著差异。Tj-1井的内陆架主要种为星螺（Asterorotalia pulchella）和副种（Pseudorotalia schroeteriana）。而Tp-1井中以绿绿假罗塔利亚（Pseudorotalia schroeteriana）为主，而无星罗塔利亚（Asterorotalia pulchella）。对于三角洲前缘物种，在Tp-1井中发现了Bigenerina sp.和Reophax sp.。而在Tj-1井中，主要的组合是在serravalliian - Tortonian期间的Bigenerina sp.和milammina sp.，以及在Tortonian - Messinian期间的Cavarotalia annectens。此外，根据马来盆地标准孢粉带（“PR”带）的地层定年，根据VIM（越南-印尼-马来西亚）和SEA（东南亚）旋回的年龄推断，我们的研究确定了琅吉安- Serravallian时期的一次主要海侵-退退（T-R）事件，这也突出了不整合。这表明构造事件在中新世生物地层组合中导致了不同的动物群省。

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引用次数: 0

The optical textures of pyrobitumen in nature and its geological significance: revealed from the Ediacaran pyrobitumen in the central Sichuan Basin, SW China 四川盆地中部埃迪卡拉系焦沥青的光学结构及其地质意义

Journal of Palaeogeography

Pub Date : 2025-07-10 DOI: 10.1016/j.jop.2025.100271

Lian-Qiang Zhu , Ze-Zhang Song , Bing Luo , Guang-Di Liu , Wen-Zhi Zhao , Qian-Qian Feng , Ben-Jian Zhang , Gang Zhou , Xing-Wang Tian , Dai-Lin Yang , Lu-Ya Wu , Lin Ma , Mikhail Spasennykh , Yi-Shu Li

Some natural pyrobitumens exhibit optical anisotropy similar to mesophase asphalt, potentially recording critical geological information. However, the significance of their distinctive optical textures remains understudied. Anisotropic pyrobitumen in the Ediacaran Dengying Formation (central Sichuan Basin, southwestern China) provides a key example. This study investigates controls on pyrobitumen optical texture evolution using petrography, scanning electron microscopy, and U–Pb dating. Then, it discusses the relationship between these textures and anomalous thermal events by analyzing their spatial distribution and their geological significance. Results reveal that anisotropic pyrobitumen in Dengying Formation formed from oil cracking caused by Late Permian hydrothermal activity. These pyrobitumen can be divided into two categories based on the optical textures: fibrous and mosaic, reflecting distinct internal physical structures. Fibrous pyrobitumen exhibits more ordered aromatic layers than the mosaic type. Temperature primarily controls optical textures by regulating polycondensation reactions and pyrobitumen viscosity. Although the Gaoshiti and Moxi areas share similar burial histories, Gaoshiti is dominated by highly evolved fibrous pyrobitumen, while Moxi contains predominantly low-evolved mosaic pyrobitumen. This disparity indicates formation of anisotropic pyrobitumen was unrelated to normal burial temperatures but to hydrothermal activity. This study demonstrates that anisotropic pyrobitumen cannot form below 240 °C, even over extended durations. Consequently, in situ anisotropic pyrobitumen in deep strata serves as an indicator of paleo-thermal anomalies, with varying textures acting as proxies for relative temperatures within these events. Under identical geological settings, fibrous pyrobitumen typically records higher temperatures than mosaic pyrobitumen.

一些天然焦沥青表现出与中间相沥青相似的光学各向异性，可能记录关键的地质信息。然而，它们独特的光学结构的意义仍未得到充分研究。四川盆地中部埃迪卡拉系灯影组各向异性焦沥青就是一个典型的例子。本研究利用岩石学、扫描电镜和U-Pb测年技术研究了焦沥青光学结构演化的控制因素。然后，通过分析其空间分布及其地质意义，讨论了这些结构与异常热事件的关系。结果表明，灯影组各向异性热液沥青是由晚二叠世热液活动引起的石油裂解形成的。这些焦沥青根据其光学结构可分为纤维状和镶嵌状两类，反映出不同的内部物理结构。纤维状焦沥青的芳香层比镶嵌型的更有序。温度主要通过调节缩聚反应和焦沥青粘度来控制光学结构。高石梯与磨溪地区埋藏史相似，但高石梯以高演化的纤维状焦沥青为主，磨溪以低演化的马赛克焦沥青为主。这种差异表明各向异性焦沥青的形成与正常埋藏温度无关，而与热液活动有关。该研究表明，即使在较长的时间内，各向异性焦沥青也不能在240°C以下形成。因此，深部地层的原位各向异性焦沥青可作为古热异常的指示物，不同的结构可作为这些事件中相对温度的代用物。在相同的地质条件下，纤维状焦沥青通常比镶嵌式焦沥青记录更高的温度。

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引用次数: 0

Plio–Pleistocene water cooling in the southeastern Pacific Ocean: Insights from paleoecology, marine sedimentary facies analysis, and Sr isotope stratigraphy at Coquimbo (∼30°S), Chile 东南太平洋上新世-更新世水冷却：来自古生态学、海洋沉积相分析和智利Coquimbo(~ 30°S) Sr同位素地层学的见解

IF 2

Journal of Palaeogeography

Pub Date : 2025-07-08 DOI: 10.1016/j.jop.2025.100269

Diego Partarrieu , Luisa Pinto , Constanza García , Saleta de los Arcos , Melissa González , Gabriela Solís-Pichardo , Gerardo Arrieta-García , Teodoro Hernández-Treviño , Peter Schaaf , Francisco Fonseca , F. Amaro Mourgues , Pablo Oyanadel-Urbina , Martín Chávez-Hoffmeister , Jorge D. Carrillo-Briceño , Valentina Flores-Aqueveque , Patricio Zambrano-Lobos , Cristina Ortega , Marcelo M. Rivadeneira

Understanding the oceanographic and environmental changes experienced on the South American Pacific coast during the Plio–Pleistocene transition and the influence of these variations on the evolution of marine ecosystems is particularly interesting to assess the effects of current global climate projections. We present a stratigraphic model of the marine sedimentary successions exposed in Coquimbo (∼30°S), northern Chile, supported by 22 numerical ages from the last 6 Ma obtained through ⁸⁷Sr/⁸⁶Sr dating of fossil mollusk shells. This stratigraphic model, and paleoecological and sedimentary facies analyses allow us to interpret the paleoenvironmental evolution and depositional dynamics in the basin. The marine successions accumulated in four sedimentation episodes: the first two on the shoreface during Messinian–Zanclean (∼6–5.10 Ma) and Zanclean–Piacenzian (∼4.23–3 Ma) ages, whereas the last two occurred mainly on the foreshore during middle Calabrian (∼1.15 Ma) and late Calabrian–Chibanian (∼0.83–0.25 Ma). The most significant taxonomic changes are observed in the transition between the Pliocene and Pleistocene deposits (∼3–1.15 Ma), reflecting the shift from faunal associations typical of warm-temperate waters to others of cool-temperate water preferences. The faunal turnover identified in this study correlates well with two climatic transition pulses out of three previously recognized in the southeastern Pacific Ocean for the Plio–Pleistocene: one during the Piacenzian–Gelasian (3–2.4 Ma), marked by a decrease in water temperature and an expansion of upwelling zones in the Humboldt Current System; and the other during the Gelasian–Calabrian (2–1.5 Ma), which has been linked to the establishment of the current El Niño Southern Oscillation (ENSO) climate system.

了解南美太平洋沿岸在上新世-更新世过渡时期经历的海洋和环境变化，以及这些变化对海洋生态系统演变的影响，对于评估当前全球气候预测的影响尤为重要。本文建立了智利北部Coquimbo（~ 30°S）海相沉积序列的地层模型，并通过对软体动物化石进行87Sr/86Sr测年得到了近6 Ma的22个数值年龄。该地层模型和古生态、沉积相分析有助于解释盆地的古环境演化和沉积动力学。海相序列在4个沉积期积累：前两个沉积期在迈西尼亚-赞克利世（~ 6-5.10 Ma）和赞克利安-皮亚森世（~ 4.23-3 Ma）的岸边，后两个沉积期主要发生在中卡拉布里亚（~ 1.15 Ma）和晚期卡拉布里亚-奇班尼亚（~ 0.83-0.25 Ma）的前岸边。最显著的分类学变化发生在上新世和更新世沉积物（~ 3-1.15 Ma）之间，反映了从典型的暖温带水域的动物组合到其他冷温带水域的动物组合的转变。本研究中发现的动物更替与先前在上新世-更新世期间在东南太平洋发现的三个气候转变脉冲中的两个有很好的相关性：一个是在皮亚先世-格拉西亚（3-2.4 Ma）期间，以水温下降和洪堡洋流系统上升流带的扩大为标志；另一次是在Gelasian-Calabrian （2-1.5 Ma）期间，这与当前El Niño南方涛动（ENSO）气候系统的建立有关。

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引用次数: 0

Lithofacies division and intelligent identification of the lacustrine mixed rocks in the Upper Xiaganchaigou Formation in Yingxi area of the Qaidam Basin, northwestern China 柴达木盆地英西地区下干柴沟组上段湖相混岩岩相划分及智能识别

Journal of Palaeogeography

Pub Date : 2025-07-08 DOI: 10.1016/j.jop.2025.100270

Yong-Shu Zhang , Jia-Lin Fu , Kun-Yu Wu , Wu-Rong Wang , Ying-Hai Jiang , Shu-Qi Zhang , Jian Li , Han Wang , Li-Ben Deng , Zi-Mo Xu , Na Zhang , Cheng-Zao Jia , Da-Li Yue

The Lower Ganchaigou Formation in the Yingxi area of the Qaidam Basin is a typical lacustrine mixed rock reservoir in western China. It is characterized by strong interlayer heterogeneity, development of diverse lithofacies types, and complex response features in logging curves. These complexities make lithofacies identification of the Ganchaigou Formation particularly challenging for non-coring wells, demanding a more efficient and accurate approach. Based on lithology and structural patterns, a lithofacies classification scheme was established. Three intelligent logging identification methods based on improved long short-term memory (LSTM) networks were constructed for lithofacies identification. The accuracy of these methods was evaluated, and the most suitable intelligent logging identification method for the reservoir lithofacies in the Yingxi area was selected. In the Upper Xiaganchaigou Formation (E₃² section) of the Yingxi area, a total of eight lithofacies types were identified: laminated lime-dolostone, stratified lime-dolostone, laminated dolostone-lime, stratified dolostone-lime, laminated lime-dolomitic shale, massive mudstone, sandstone, and gypsum. The overall recognition accuracies of the LSTM, Bi-LSTM, and Attention-based Bi-LSTM intelligent identification models are 81%, 85%, and 87%, respectively. The overall recognition accuracies of the three intelligent algorithms are relatively high, with the Attention-based Bi-LSTM model achieving the highest accuracy. This model demonstrates superior applicability for intelligent lithofacies identification in lacustrine mixed rock reservoirs, particularly those dominated by carbonates in the Yingxi area. It effectively interprets the lithofacies types of non-coring wells in the study area and provides a valuable reference for interpreting lithofacies logs in similar depositional environments.

柴达木盆地英西地区下干柴沟组是中国西部典型的湖相混合岩储层。层间非均质性强，岩相类型多样，测井曲线响应特征复杂。这些复杂性使得干柴沟组岩相识别对非取心井来说尤其具有挑战性，需要更有效、更准确的方法。根据岩性和构造模式，建立了岩相划分方案。构建了3种基于改进长短期记忆（LSTM）网络的岩相智能测井识别方法。评价了这些方法的精度，选择了最适合英西地区储层岩相的智能测井识别方法。英西地区下干柴沟组上段（E32剖面）共识别出8种岩相类型：层状灰岩、层状灰岩、层状白云岩、层状白云岩、层状灰岩-白云岩、层状灰岩-白云岩页岩、块状泥岩、砂岩、石膏。LSTM、Bi-LSTM和基于注意力的Bi-LSTM智能识别模型的总体识别准确率分别为81%、85%和87%。三种智能算法的整体识别精度都比较高，其中基于注意力的Bi-LSTM模型的识别精度最高。该模型在莺西地区以碳酸盐岩为主的湖相混合储层智能岩相识别中具有较好的适用性。有效地解释了研究区非取心井的岩相类型，为类似沉积环境的岩相测井解释提供了有价值的参考。

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引用次数: 0

Sedimentary facies architecture and terminal fan systems of the lower Palaeogene Shahejie formation in Bonan Sag, Bohai Bay Basin, China: implications for hydrocarbon exploration 渤海湾盆地渤南凹陷下古近系沙河街组沉积相构型及末端扇体系对油气勘探的启示

IF 2

Journal of Palaeogeography

Pub Date : 2025-07-03 DOI: 10.1016/j.jop.2025.100268

Arthur Paterne Mioumnde , Li-Qiang Zhang , Yi-Ming Yan , Lauben Twinomujuni , Hong-Wei Ran , Victor Sedziafa , Kevin Zebaze Djuka , Moise Bessong , Emmanuel Melaine Kouame

In the search for oil reservoirs within the lower fourth member of the Paleogene Shahejie Formation (Es4x), understanding the depositional model is crucial, particularly in the Bonan Sag of the Bohai Bay Basin. Previous studies have provided limited perspectives on the depositional mechanisms in complex geological settings characterized by tectonic orogeny, volcanic activity, and metamorphism. This research seeks to address this knowledge gap by focusing on sedimentary deposits formed by the terminal fan system, diverging from the more commonly studied fan delta models. This study aims to clarify the depositional environment and mechanisms of the Es4x Member by identifying and characterizing the sedimentary facies and exploring how provenance influences the distribution of sandstone reservoirs in this heterogeneous formation. Data from more than 20 wells and over 500 m of cores revealed 15 lithofacies types, which were grouped into five facies associations (FA1--FA5) and used to describe the depositional architecture. These subfacies are categorized into feeder, distributary, and basal zones, with proximal, medial, and distal subfacies. Lithological analysis identified the dominant rock types as lithic arkose, feldspathic litharenite, and litharenite. The results show that the medial subfacies dominates the Bonan Sag during the deposition of the Es4x Member, occasionally extending towards the basinal zone through sporadic diffuse flood channels. This depositional mechanism reflects ephemeral water stretches influenced by varying weather conditions. Volcanic clasts distributed beyond the terminal fan system further illustrate the influence of volcanic activity on depositional processes. This study provides key findings on the sedimentary mechanisms in the Es4x Member, offering important information regarding deep reservoirs in tectonically active areas, particularly the challenges of predicting oil reservoirs in thin versus thick red beds.

在渤海湾盆地渤南凹陷古近系沙河街组下四段寻找油藏的过程中，认识沉积模式至关重要。以往的研究对以构造造山、火山活动和变质作用为特征的复杂地质环境下的沉积机制提供了有限的认识。本研究试图通过关注由末端扇系统形成的沉积沉积来解决这一知识差距，与更常见的扇三角洲模型不同。本研究旨在通过对沙四x段沉积相的识别和表征，探讨物源对该非均质地层砂岩储层分布的影响，明确沙四x段沉积环境和沉积机制。来自20多口井和500多米岩心的数据揭示了15种岩相类型，并将其分为5种相组合（FA1—FA5），用于描述沉积构型。这些亚相可分为补给带、分流带和基底带，并分为近端、中端和远端亚相。岩性分析表明，主要岩石类型为岩屑长石、长石岩屑岩和岩屑岩。结果表明：渤南凹陷沙四段沉积时期以内侧亚相为主，偶尔通过零星扩散洪道向盆地延伸；这种沉积机制反映了受不同天气条件影响的短暂的水伸展。分布在末端扇体系之外的火山碎屑进一步说明了火山活动对沉积过程的影响。该研究提供了Es4x段沉积机制的关键发现，为构造活跃区深部储层提供了重要信息，特别是对薄层与厚层红层储层预测的挑战。

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引用次数: 0

The Paleocene syncollisional deposits in Renbu, southern Tibet, China: New insights into the foredeep–wedge evolution of the Himalayan foreland 藏南仁部古新世同碰撞沉积：喜马拉雅前陆前深楔演化新认识

Journal of Palaeogeography

Pub Date : 2025-07-01 DOI: 10.1016/j.jop.2025.100263

Zhen Wei , Xiang-Hui Li , Min-Jia Sun , Xiao-Long Fan , Jing-Yu Wang

Understanding turbidites and olistostromes in the foredeep depozone is critical for deciphering foreland–orogenic wedge interactions. Despite the abundance of syncollisional deposits in the central Himalaya, current research lacks analysis of their depositional models in this context. Our study focuses on the Renbu Unit, a recently discovered Paleocene syncollisional deposits in Renbu, assessing its lithological composition, sedimentary environment, and provenance. The lower part of the Renbu Unit is characterized by fine-grained turbiditic sandstones, showcasing maximum depositional ages of ∼80 Ma. Contrarily, the upper part, composed of coarse-grained turbiditic sandstones, presents a maximum depositional age of ∼64 Ma. The sandstones sources vary from the recycled Xigaze forearc basin in the lower unit to the Gangdese arc in the upper unit. Hence, the lower Renbu Unit could equate to the Jiachala Formation, and the upper Renbu Unit could correspond to its eroded counterpart whose zircon geochronology fits the biostratigraphic data of the Jiachala Formation. This leads to a new depositional model suggesting near-contemporaneous deposition of the Zongzhuo mélange, Jiachala Formation, and the Renbu Unit in the foredeep, demonstrating events like the orogenic front's collapse and gravity flow deposition.

了解前深沉积带中的浊积岩和鲕粒岩对于解释前陆-造山带的相互作用至关重要。尽管喜马拉雅中部有丰富的同碰撞矿床，但目前的研究缺乏在这种背景下对其沉积模式的分析。本文以新发现的仁部古新世同碰撞矿床仁部单元为研究对象，对其岩性组成、沉积环境和物源进行了评价。人步单元下部以细粒浊积砂岩为特征，最大沉积时代为~ 80 Ma。上部由粗粒浊积砂岩组成，最大沉积年龄为~ 64 Ma。砂岩源区从下单元日喀则弧前盆地的再循环到上单元冈底斯弧。据此，下人布单元可与嘉查拉组对应，上人布单元可与侵蚀后的嘉查拉组对应，其锆石年代学与嘉查拉组生物地层资料吻合。在此基础上，建立了宗卓组、贾恰拉组和仁布组近同时期沉积的新沉积模式，反映了造山带前缘崩塌和重力流沉积等事件。

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引用次数: 0

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