Journal of Asian Earth Sciences最新文献_第7页

New paleoseismological constraints on the seismic activity along the eastern Tunka Fault (SW Baikal Rift) 东通卡断裂带（西南贝加尔湖裂谷）地震活动的古地震学新约束

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-04 DOI: 10.1016/j.jseaes.2025.106901

A.A. Chebotarev , A.V. Arzhannikova , S.G. Arzhannikov , J.-F. Ritz , A.V. Avagyan

The Tunka Fault, a major active structure in the southwestern Baikal Rift system, poses a significant seismic hazard, yet its paleoseismic history remains poorly constrained. We present new paleoseismic data from trenches across its eastern Tory segment, constrained with morphotectonic analysis and radiocarbon dating. Our results reveal two Holocene earthquakes, corresponding to the E2 and E3 events identified in previous studies along the Mondy, Tunka, and Main Sayan faults. These three faults have been interpreted as having produced seismic clusters at least four times in the Late Pleistocene-Holocene times. Our radiocarbon data allow constraining more tightly the ages of the E2 and E3 events to 3170–3399 and 8453–8540 cal yr BP, respectively. Morphotectonic analysis of the Tory site, together with published data along the adjacent section of the Tunka Fault, showed that the average amplitude of displacement per event along the slip vector was 2.1 m, corresponding to a magnitude of Mw 7.3. In some cases, all fault segments seem to have ruptured simultaneously over a length of 200 km, while in others cases, only segments striking E-W and NW-SE directions ruptured with a reverse slip component. Fault segments with normal slip component ruptured with a delay, but with a similar recurrence interval. These results highlight the potential for multi-fault ruptures in the Baikal region and challenge existing seismic hazard models. Our study provides critical input for revising probabilistic seismic hazard assessments and underscores the need to consider fault interaction in tectonic settings with complex block boundaries.

Tunka断裂是贝加尔湖裂谷系西南部的一个主要活动构造，具有重大的地震危险性，但其古地震史却知之甚少。通过形态构造分析和放射性碳定年，我们提出了新的古地震数据，这些数据来自东托里段的沟槽。我们的研究结果揭示了两个全新世地震，对应于先前研究中发现的沿着Mondy， Tunka和Main Sayan断层的E2和E3事件。这三条断层被解释为在晚更新世-全新世期间至少四次产生了地震群。我们的放射性碳数据可以更严格地将E2和E3事件的年龄分别限制在3170-3399和8453-8540 calyr BP之间。托里地区的形态构造分析，连同Tunka断层邻近部分的已发表数据，表明沿滑动矢量每次事件的平均位移幅度为2.1 m，相当于7.3 Mw的震级。在某些情况下，所有断层段似乎在200公里长的范围内同时破裂，而在其他情况下，只有E-W和NW-SE方向的断层段破裂，并伴有逆滑成分。具有正常滑动分量的断层段的破裂具有延迟性，但具有相似的复发间隔。这些结果突出了贝加尔湖地区多断层破裂的可能性，并对现有的地震危险性模型提出了挑战。我们的研究为修正概率地震危险性评估提供了关键的输入，并强调了在具有复杂块体边界的构造环境中考虑断层相互作用的必要性。

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引用次数: 0

Insights on the structural framework of the Ailaoshan Orogenic Belt from gravity data 从重力资料看哀牢山造山带构造格架

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-03 DOI: 10.1016/j.jseaes.2025.106902

Nguyen Ngoc Long , David Gomez-Ortiz , Nguyen Kim Dung , Luan Thanh Pham

One of the important tasks in mapping geological structures is determining the horizontal boundaries of density structures. These boundaries can be estimated by using the edge detection techniques of gravity data. In this study, we apply several traditional edge enhancement filters along with recently developed techniques to the Bouguer gravity data to analyze structural trends and fault zones in the Ailaoshan Orogenic Belt, which is known as a significant suture zone between the South China Block and the Indochina Block. The edge recognition capabilities of these filters are examined using both noise-free and noisy synthetic gravity data before applying them to real gravity anomaly data of the belt. The structural features from the edge detection techniques are also confirmed by the Euler deconvolution method, where the result shows that the depth estimates in the Ailaoshan Orogenic Belt change from 0.9 to 4.7 km. The findings show that edge detection techniques produce anomaly maps that are well-correlated with the main tectonic framework of the study area, which trends NW-SE. These techniques are also helpful in identifying some structural features that are not visible at the surface, thus contributing to a more complete crustal framework of the Ailaoshan Orogenic Belt.

地质构造填图的重要任务之一是确定密度构造的水平边界。这些边界可以用重力数据的边缘检测技术来估计。本文将几种传统的边缘增强滤波方法与最新发展的布格重力数据相结合，对哀牢山造山带的构造走向和断裂带进行了分析。哀牢山造山带是华南地块和印度支那地块之间的重要缝合带。在将这些滤波器应用于实际重力异常数据之前，分别使用无噪声和有噪声的合成重力数据对其边缘识别能力进行了检验。欧拉反褶积方法也证实了边缘检测技术的构造特征，结果表明哀牢山造山带的深度估计在0.9 ~ 4.7 km之间变化。结果表明，边缘检测技术得到的异常图与研究区北西-东向的主构造格架具有较好的相关性。这些技术还有助于识别一些地表不可见的构造特征，从而使哀牢山造山带的地壳格架更加完整。

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引用次数: 0

Constraints of the paleo-trade wind route on the paleo-geography of the South China Block in the Late Permian (Lopingian)-Early Triassic 晚二叠世（洛平纪）-早三叠世古信风路径对华南地块古地理的制约

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-03 DOI: 10.1016/j.jseaes.2025.106900

Rufei Peng , Chenlin Hu , Xin Li , Hongmei Su , Jonathan Atuquaye Quaye , Cheng Dong

South China Block (SCB) is situated in the Eastern Asian margin. During the crucial transitional Formation of the Permian-Triassic boundary in geological history, the SCB was located in a shallow sea environment within the low-latitude trade winds zone, accumulating marine sedimentary deposits. There are numerous studies concerned on the paleoecological and biological evolution of the SCB, but studies of paleogeography are few and the paleogeographic position of the SCB remains as a matter of debate. In this paper, we describe the sedimentary features of Late Permian (Lopingian) to Early Triassic in the Sichuan Basin, northwestern SCB, and present new magnetic fabrics for these sequences. The results of sedimentary differentiation and anisotropy of magnetic susceptibility indicated prevailing wind routes of 106.6° ± 4.3° east of north in the Late Permian and 118.2° ± 4.7° east of north in the Early Triassic. After correcting for a 70° clockwise rotation of the SCB since the Permian-Triassic boundary, the paleo-wind routes are reconstructed as 36.6° ± 4.3° and 48.2° ± 4.7° east of paleo-north for these periods. The study of the paleo-wind routes indicates that the SCB migrated northward from a near-equatorial position in the Late Permian (Lopingian) to a more distant location in the Early Triassic, marking significant movement within the Northern Hemisphere. The paleogeographic position of the SCB was determined by aligning its quantitatively reconstructed predominant paleo-wind routes with the latitudinal variation of Northern Hemisphere trade wind patterns. This analysis indicates that the SCB was located near the equator in the Late Permian and had migrated northward within the Northern Hemisphere by the Early Triassic. These findings provide insights into the paleoclimate and paleogeographic evolution of the SCB and offer data for other studies. Moreover, the methodology employed in this study serves as a useful reference for paleogeographic and paleoclimatic reconstructions of other ancient landmasses.

华南地块（SCB）位于东亚边缘。在地质历史上二叠纪-三叠纪界线的关键过渡期，南海处于低纬度信风带内的浅海环境，聚集了海相沉积。近年来，学界对其古生态和生物演化的研究较多，但对其古地理的研究较少，对其古地理位置的研究也存在争议。本文描述了华南西北地区四川盆地晚二叠世（洛平期）至早三叠世的沉积特征，并提出了这些层序的新磁组构。沉积分异和磁化率各向异性结果表明，晚二叠世盛行风路径为北偏东106.6°±4.3°，早三叠世盛行风路径为北偏东118.2°±4.7°。在校正了自二叠纪—三叠纪界线以来SCB的顺时针旋转70°后，重建的古风路径为古北偏东36.6°±4.3°和48.2°±4.7°。古风路研究表明，SCB在晚二叠世（洛平纪）从近赤道位置向北迁移到早三叠世较远的位置，标志着北半球内的重大运动。通过将定量重建的主要古风路与北半球信风型的纬向变化进行比对，确定了南海的古地理位置。这一分析表明，SCB在晚二叠世时位于赤道附近，并在早三叠世时在北半球向北迁移。这些发现为研究南海的古气候和古地理演化提供了新的思路，并为其他研究提供了数据。此外，本文所采用的方法对其他古陆块的古地理和古气候重建也有借鉴意义。

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引用次数: 0

Jurassic tectonic activity and geodynamic implications of the eastern segment of the Altyn Tagh Fault, Northwest China 阿尔金断裂带东段侏罗系构造活动及其地球动力学意义

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-02 DOI: 10.1016/j.jseaes.2025.106899

Huaiwei Feng , Shumei Xu , Jinduo Wang , Hongzhuang Cui , Xiangfeng Wu

The Altyn Tagh Fault (ATF), forming the northern boundary of the present-day Tibetan Plateau, cuts across multiple structural units of northern Tibetan Plateau and exerts a fundamental control on the framework of the Mesozoic-Cenozoic sedimentary basins. Although numerous studies have investigated the timing and magnitude strike-slip motion along the ATF, its Jurassic evolution remains poorly constrained. In this study, we integrate sedimentological, structural, geophysical, and thermochronological approaches to examine the Jurassic tectonic activity of the eastern segment of the ATF. Analyses of soft-sediment deformation structures indicate that the Altyn Tagh Range experienced incipient, submarine uplift without the development of significant surface topography. The recognition of Jurassic stratigraphic contacts and flower structures in seismic profiles further suggests localized uplift and strike-slip deformation. Detrital zircon U-Pb age spectra exhibit near-source signatures, implying restricted lateral displacement along the fault during the Jurassic. Moreover, aeromagnetic anomaly interpretation combined with low-temperature thermochronology indicates that the ATF operated within a dynamic framework involving pre-Jurassic southward deep subduction of the Tarim Block and northward shallow subduction of the Qaidam Block, mediated by a deep lithosphere-mantle ductile shear zone. Under this tectonic configuration, the fault experienced limited strike-slip motion, segmented activity, and localized uplift during the Jurassic.

尽管许多研究已经调查了沿ATF的走滑运动的时间和规模，但其侏罗纪演化仍然知之甚少。在这项研究中，我们综合了沉积学、构造学、地球物理和热年代学的方法来研究ATF东段的侏罗纪构造活动。软沉积变形构造分析表明，阿尔金山脉经历了早期的海底隆升，没有明显的地表地形发育。地震剖面对侏罗系地层接触和花状构造的识别进一步表明了局部隆升和走滑变形。碎屑锆石U-Pb年龄谱表现出近源特征，表明侏罗纪时期沿断层侧向位移受限。此外，航磁异常解释结合低温热年代学表明，ATF是在塔里木地块前侏罗世向南深俯冲和柴达木地块向北浅俯冲的动力框架内运行的，并以深部岩石圈-地幔韧性剪切带为介质。在这一构造构型下，断层在侏罗纪经历了有限的走滑运动、分段活动和局部隆升。

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引用次数: 0

Tectonic and climate control on the stratigraphic cycles in a Late Paleozoic evaporitic basin in NW China 构造和气候对西北晚古生代蒸发盆地地层旋回的控制

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-02 DOI: 10.1016/j.jseaes.2025.106898

Kuanhong Yu , Shuo Du , Yingchang Cao , Zi Wang

The Fengcheng Formation in the Junggar Basin, northwestern China, represents a suite of deposits formed in a hydrologically closed, alkaline saline lake during the Late Paleozoic. This formation hosts high-quality source rocks (oil shales) and significant trona resources. Closed-basin lacustrine systems exhibit stratigraphic architectures that are fundamentally distinct from those of marine or open-lake settings; consequently, conventional sequence stratigraphic models are often inadequate for interpreting the distribution of trona and oil shale resources within such confined depositional systems. Based on integrated analyses of drilling sequences, well logs, and seismic profiles, we identify four key findings: (1) Three third-order sequences can be delineated using lithostratigraphic patterns and seismic-stratigraphic relationships; (2) The Mahu Sag remained predominantly underfilled throughout most of the depositional history, evolving into a balanced-fill basin only at the end of Sequence 3 (SQ3); (3) Trona deposition occurred during arid phases within repeated climatic cycles, with the Fengcheng Formation preserving four long-term cycles, each comprising multiple intermediate- and short-term climatic fluctuations; (4) The highest-quality oil shales accumulated during the transgressive systems tracts (TST) of SQ1 and SQ2, coinciding with periods of rising lake levels. Additional oil shale intervals formed at the onset of individual cycles when lake levels were elevated. These findings offer a comprehensive stratigraphic framework for understanding the spatial and temporal distribution of trona and oil shale resources in a Late Paleozoic alkaline saline lake system characterized by asymmetric basin geometry.

准噶尔盆地丰城组是一套晚古生代水文封闭的碱性盐湖沉积。该地层拥有优质烃源岩（油页岩）和重要的天然气资源。封闭盆地湖泊体系的地层结构与海相或开阔湖泊的地层结构有本质的区别；因此，常规的层序地层学模型往往不足以解释此类封闭沉积体系中地下和油页岩资源的分布。通过对钻井序列、测井曲线和地震剖面的综合分析，得出了四个重要发现：(1)利用岩石地层模式和地震-地层关系圈定了3个三级层序；(2)马湖凹陷在大部分沉积历史中以欠充填为主，仅在层序3 （SQ3）末演化为平衡充填盆地；(3) Trona沉积发生在干旱期，在重复的气候周期中，丰城组保存了4个长期周期，每个周期包含多个中短期气候波动；(4)油页岩质量最高的时期为SQ1和SQ2海侵体系域（TST），与湖泊水位上升时期一致。当湖泊水位升高时，在个别旋回开始时形成额外的油页岩层段。这些发现为认识具有不对称盆地几何特征的晚古生代碱性盐湖体系中烃类和油页岩资源的时空分布提供了一个全面的地层框架。

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引用次数: 0

A refined classification of 3D shape preferred orientation patterns in fault gouges: Insights from the Yangsan and Ulsan Fault Zones, South Korea 断层带中三维形状优选方向模式的精细分类：来自韩国梁山和蔚山断裂带的见解

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-02 DOI: 10.1016/j.jseaes.2025.106896

Ho Sim , Seongsik Hong , Yungoo Song , Seung-Ik Park , Changyun Park

Shape preferred orientation (SPO) analysis of rigid clasts in fault rocks is a fundamental tool for understanding grain-scale deformation process. However, the occurrence of anomalous patterns in 3D-SPO data has challenged traditional interpretations that rely solely on clast rotation systems observed in cross-sections. Here, we present a novel classification system for 3D-SPO patterns that accounts for the critical influence of clast morphology. Through integrated analysis of X-ray diffraction patterns, μ-CT imaging, 3D-SPO analysis, and electron microscopy data for three samples from the Yangsan and Ulsan fault zones (southeastern Korean Peninsula), we demonstrate that clast final shape and fabric under shear are primarily controlled by clast morphology, possibly combined with initial orientation. We classified all samples into four types based on clast morphology and identified six distinct SPO patterns associated with these classifications: top-spinning (type-S) and oblate-rolling (type-OR) for oblate type clasts, rotating (type-R) and prolate-rolling (type-PR) for prolate type clasts, and two distinct rotating patterns (types H and V) for bladed type clasts. Natural fault gouge typically exhibits a composite of these patterns, with the dominant pattern reflecting the predominant clast shape population. This refined understanding of the relationship between clast shape and SPO patterns significantly improves the reliability of SPO analysis and enhances our ability to reconstruct fault deformation process.

断裂岩中刚性碎屑的形状优先取向（SPO）分析是理解颗粒级变形过程的基本工具。然而，3D-SPO数据中出现的异常模式对传统的仅依赖于在横截面上观察到的碎屑旋转系统的解释提出了挑战。在这里，我们提出了一种新的3D-SPO模式分类系统，该系统考虑了碎屑形态的关键影响。通过对梁山和Ulsan断裂带3个样品的x射线衍射图、μ-CT成像、3D-SPO分析和电镜数据的综合分析，我们发现剪切作用下碎屑的最终形态和结构主要受碎屑形态的控制，可能与初始取向有关。我们根据碎屑形态将所有样品分为4种类型，并确定了与这些分类相关的6种不同的SPO模式：扁圆型碎屑的顶旋（s型）和扁圆滚动（or型），长圆型碎屑的旋转（r型）和扁圆滚动（pr型），叶片型碎屑的两种不同的旋转模式（H型和V型）。天然断层泥通常表现为这些模式的组合，主要模式反映了主要的碎屑形状种群。这种对碎屑形状与SPO模式之间关系的精细化理解大大提高了SPO分析的可靠性，增强了我们重建断层变形过程的能力。

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引用次数: 0

Provenance, tectonic setting, weathering patterns, and paleoclimate insight from late Holocene Wainganga River sediments, central India: a geochemical and statistical approach 印度中部晚全新世Wainganga河沉积物的物源、构造背景、风化模式和古气候：地球化学和统计方法

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-02 DOI: 10.1016/j.jseaes.2025.106897

Dileep Abdul Kalam T., Samaya S. Humane, Sumedh K. Humane, Shreyash Sayankar

The Geochemical composition of the Holocene sediments of the Wainganga Riverbank near Pauni town, Central India have been probed to understand the localised sedimentary evolution. The provenance of the sediments is of mostly felsic origin suggesting source rocks are granitic gneiss, granite, muscovite schists and gneiss from the adjacent area of the Wainganga River basin (WRB). The paleo weathering conditions plots suggest incipient to moderate chemical weathering. Analysis of tectonic setting discrimination diagrams demonstrate that the sediments are characteristic of a passive margin provenance. The transition from semi-arid to semi-humid climate is evident from the C-value plot and SiO₂ vs Al₂O₃ + K₂O + Na₂O diagram, with multivariate statistical analysis confirming this gradual climatic evolution. The shift in Rb/Sr and Sr/Cu ratios provide additional geochemical evidence supporting the inferred paleoclimatic shift from arid to more humid conditions accompanied by enhanced productivity. Four zones were demarcated based on the significant shifts in the geochemical ratios which are key indicators of climate shifts. The sedimentary record of Zone-I (1100–1300 cm) suggests moderate weathering, with substantial clay formation, potentially attributed to increased precipitation of changes in hydrological regime. Zone- II (800–1100 cm) represents dry period with limited moisture leading to minimal chemical weathering and better drainage or less organic matter accumulation. Zone-III (400–800 cm) shows a slight increase in weathering with more reducing conditions due to either poor drainage or high organic matter content. Zone-Ⅳ (50–400 cm) is characterised by drop in chemical weathering intensity followed by gradual increase, coinciding with a shift towards a more humid.

对印度中部波乌尼镇附近的万安加河岸全新世沉积物的地球化学组成进行了探测，以了解局部沉积演化。沉积物物源以长英质岩为主，表明烃源岩主要为邻近万因甘加河流域的花岗质片麻岩、花岗岩、白云母片岩和片麻岩。古风化条件图显示为早期至中度化学风化。构造环境判别图分析表明，沉积物具有被动边缘物源的特征。c值图和SiO2 / Al2O3 + K2O + Na2O图显示了从半干旱到半湿润气候的转变，多元统计分析证实了这一渐进的气候演变过程。Rb/Sr和Sr/Cu比值的变化提供了额外的地球化学证据，支持推断的古气候从干旱到更湿润的变化伴随着生产力的增强。根据气候变化的关键指标地球化学比值的显著变化，划分了4个带。i区（1100-1300 cm）的沉积记录表明中度风化，具有大量粘土形成，可能归因于降水增加或水文状况的变化。II区（800-1100 cm）为干燥期，水分有限，化学风化作用最小，排水较好，有机质积累较少。iii区（400 ~ 800 cm）由于排水差或有机质含量高，风化作用略有增加，还原条件较多。区域-Ⅳ（50-400厘米）的特征是化学风化强度下降，然后逐渐增加，同时向更潮湿的方向转变。

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引用次数: 0

First quantitative constraints on the Aiyongco Fault: A record of distributed strain in the western Bangong-Nujiang Fault Zone, Tibetan Plateau

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-11-29 DOI: 10.1016/j.jseaes.2025.106878

Haoxuan Zeng , Dewen Li , Jinzhao Li , Chong Zhang , Yuquan Jiang , Gaojian Miao , Zhenming Liu

The Bangong-Nujiang Fault Zone (BNFZ) separates the Qiangtang terrane to the north from the Lhasa terrane to the south within the Tibetan Plateau. How tectonic strain is accommodated across the western segment of this major suture zone remains a key unresolved question. This study focuses on the Aiyongco Fault, a major NWW-trending structure within the western BNFZ. We employ ground investigations, satellite imagery, UAV photogrammetry, trenching, and geochronological dating (¹⁴C and ¹⁰Be) to constrain its spatial distribution, timing of recent activities, slip rates, and paleoearthquakes. Our study demonstrates that the latest activity on the Aiyongco Fault occurred between 7.8 and 0.47 ka BP, i.e., during the middle to late Holocene, and that the horizontal slip rate ranges from 0.18 ± 0.01 mm/yr to 0.77 ± 0.04 mm/yr, with a vertical slip rate of 0.05 ± 0.01 mm/yr and a single-event horizontal displacement of 1.02 ± 0.17 m. The fault has experienced at least six paleoearthquake events since 21.07 ka, with an average recurrence interval of approximately 4.3–7.0 ka. These findings provide the first quantitative constraints on this active fault, suggesting that tectonic deformation in the western Tibetan Plateau is highly distributed. Our results offer foundational data for regional tectonic models and seismic hazard assessment in this area.

构造应变如何在这个主要缝合带的西段被调节仍然是一个关键的未解决的问题。本文以北北纬向的爱永错断裂为研究对象。我们使用地面调查、卫星图像、无人机摄影测量、沟槽和地质年代测定（14C和1⁰Be）来限制其空间分布、最近活动的时间、滑动率和古地震。研究表明，爱永错断裂的最新活动发生在7.8 ~ 0.47 ka BP之间，即全新世中晚期，水平滑动速率为0.18±0.01 mm/yr ~ 0.77±0.04 mm/yr，垂直滑动速率为0.05±0.01 mm/yr，单次水平位移为1.02±0.17 m。该断裂自21.07 ka以来至少经历了6次古地震事件，平均复发间隔约为4.3 ~ 7.0 ka。研究结果为该区区域构造模型和地震危险性评价提供了基础数据。

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引用次数: 0

Corrigendum to “Indosinian structural geology and tectonics of northern Thailand: A discussion based on new field observation”. [J. Asian Earth Sci. 293 (2025) 1–38/106755] “印支构造地质与泰国北部构造：基于新的野外观测的讨论”的勘误表。[J。地球科学进展，2016 (5):389 - 389 [j]

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-11-29 DOI: 10.1016/j.jseaes.2025.106876

M. Rozalli , C.K. Morley , N. Mankhemthong

引用次数: 0

Cimmerian tectonostratigraphic events in east-central Iran revealed by a long drill core of the Shemshak Group (Upper Triassic–Middle Jurassic) 上三叠统—中侏罗统Shemshak群长岩心揭示的伊朗中东部辛里纪构造地层事件

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-11-29 DOI: 10.1016/j.jseaes.2025.106895

Mohammad Ali Salehi , Markus Wilmsen , Ehsan Zamanian , Christoph Heubeck

The Upper Triassic–lower Middle Jurassic tectono-sedimentary megacycle in central Iran is represented by the Shemshak Group, deposited within the central part of the Cimmerian continent (the “Iranian Cimmerides”). It contains key information on the Mesozoic geodynamics of the Middle East during the collision of the Cimmerian terranes with Eurasia. However, detailed insights into the response of depositional systems to the complex contemporaneous tectonics are hampered by poor exposure, in particular of fine-grained strata. A new, 641-m-long core from the northern Tabas Block (east-central Iran) provides an unweathered and continuous subsurface record of the Shemshak Group. Detailed lithofacies and stratigraphic analyses refine previous lithostratigraphic and palaeoenvironmental interpretations, allowing to consider relative sea-level changes caused by Cimmerian tectonic events and/or global sea-level fluctuations. The thick siliciclastic succession of the Rhaetian Qadir Member of the Nayband Subgroup reflects rapid basin subsidence in advance of the Main Cimmerian Event (MCE). It comprises the dominant part of the Shemshak Group. In the aftermath of the MCE at the Triassic–Jurassic boundary, comparatively low subsidence rates and limited accommodation prevailed, resulting in low thicknesses of the Lower–lower Middle Jurassic mixed siliciclastic and carbonate Ab-e-Haji Subgroup. Process and stacking-pattern analyses of eleven clastic and eight carbonate lithofacies indicate a variety of continental and marine depositional environments, ranging from fluvial and deltaic to shallow-marine. Our findings significantly improve the knowledge of the tectono-stratigraphic setting of the Shemshak Group and contribute to a better understanding of the Cimmerian history of central Iran between the Late Triassic and the Jurassic.

伊朗中部上三叠统-下中侏罗统构造-沉积巨旋回以Shemshak群为代表，沉积于西默里亚大陆（“伊朗西默里亚”）中部。它包含了西梅里亚板块与欧亚大陆碰撞期间中东中生代地球动力学的关键信息。然而，由于暴露程度低，特别是细粒地层暴露程度低，很难深入了解沉积体系对复杂同时期构造的响应。来自Tabas地块北部（伊朗中东部）的一个新的641米长的岩心提供了Shemshak群未风化的连续地下记录。详细的岩相和地层分析完善了以前的岩石地层和古环境解释，允许考虑由西merian构造事件和/或全球海平面波动引起的相对海平面变化。Nayband亚群中Rhaetian Qadir段的厚硅-碎屑演替反映了主辛里纪事件（MCE）之前盆地的快速沉降。它是舍姆沙克集团的主要部分。在三叠系-侏罗系边界的MCE之后，相对较低的沉降速率和有限的调节作用占主导地位，导致中侏罗统下-下侏罗统Ab-e-Haji混合硅屑-碳酸盐亚群厚度较低。11个碎屑岩相和8个碳酸盐岩岩相的沉积过程和叠合模式分析表明，该区存在河流三角洲和浅海相等多种陆相和海相沉积环境。我们的发现大大提高了对Shemshak群构造地层背景的认识，有助于更好地理解伊朗中部晚三叠世至侏罗纪之间的辛默纪历史。

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