Journal of Asian Earth Sciences最新文献_第5页

Obstacle leads to local stress reorientation: Insights from the formation mechanism of the Maiduoshan superimposed fold in the Weiningbeishan fold-thrust belt, NW China 障碍导致局部应力重新定向：从中国西北部威宁北山褶皱推覆带麦积山叠加褶皱形成机制的启示

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-10-04 DOI: 10.1016/j.jseaes.2024.106361

Pengchao Zhou , Xuanhua Chen , Yiping Zhang , Zhaogang Shao , Bing Li , Tao Jiang , Daxing Xu

The Maiduoshan superimposed fold, located southwest of the Weiningbeishan fold-thrust belt in the transitional zone of the Tibetan Plateau, Alxa Block, and Ordos Basin, has a lotus shape. There are more than five chevron-like hinge zones in its east, which indicates that this fold has undergone structural superposition. After a detailed structural analysis and the results of three sandbox models, we propose that the Maiduoshan superimposed fold formed due to the superposition of two asynchronous tectonic events. During the Middle–Late Triassic, E–W-trending close and tight folds formed under the N–S compression. During the Pliocene–Quaternary, the left-lateral simple shear of the Yantongshan Fault caused early E–W-trending close and tight folds to refold. In addition, the results of the sandbox models suggest obstacles to the northwest of Maiduoshan. We speculate that the concealed pluton, formed during the Middle Jurassic–early Early Cretaceous in the Jinchangzi–Errenshan area to the northwest of Maiduoshan, acted as an obstacle that hindered the drag folds (formed by the left-lateral simple shear of the Yantongshan Fault) from moving northwestward. Lastly, we propose a local stress reorientation mechanism to explain the formation of a strain field with obstacles. In such a mechanism, the different external stresses applied by obstacles at different locations lead to the reorientation of the local stresses at different locations.

麦积山叠加褶皱位于青藏高原、阿拉善地块和鄂尔多斯盆地过渡带的威宁北山褶皱推覆带西南部，呈莲花状。其东部有五条以上的楔形铰带，表明该褶皱经历了构造叠加。经过详细的构造分析和三个沙盘模型的结果，我们提出，麦积山叠加褶皱是由两个不同步构造事件叠加形成的。三叠纪中-晚期，在N-S向挤压作用下形成了E-W向的紧密褶皱。在上新世-第四纪期间，燕山断层的左侧简单剪切导致早期的 E-W 向紧密褶皱重新折叠。此外，沙盘模型的结果表明，麦积山西北部存在障碍。我们推测，形成于中侏罗世-早白垩世早期、位于麦积山西北部的金昌子-二人山地区的隐伏岩体是阻碍拖动褶皱（由岩通山断层左侧简单剪切形成）向西北移动的障碍。最后，我们提出了一种局部应力重定向机制来解释障碍应变场的形成。在这一机制中，不同位置的障碍物所施加的外应力不同，导致不同位置的局部应力重新定向。

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引用次数: 0

Morphotectonic analysis of strike-slip faults in the Sayan-Tuva Upland (North Mongolia and South Siberia): Age and displacement rates 萨彦-图瓦高原（北蒙古和南西伯利亚）走向滑动断层的形态构造分析：年龄和位移速率

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-10-04 DOI: 10.1016/j.jseaes.2024.106355

A.V. Arzhannikova , S.G. Arzhannikov , A.A. Chebotarev , S.A. Sokolov

The Sayan-Tuva Upland is the northernmost positive relief of Central Asia, associated with the India-Asia collision. It formed on the boundary of the Siberian Craton in late Miocene-early Pliocene time and is characterized by uplift and shear displacement of lithospheric blocks. In this study, we answer the question of how deformation is distributed within the Sayan-Tuva Upland and what are the rates and age of horizontal displacements. Using morphotectonic and palaeoseismological analyses, we have calculated the displacement rates and onset of activation of three faults: Erzin-Agardag, Sayan-Tuva and Kaakhem, which are fragments of large strike-slip fault systems that cut across the entire Sayan-Tuva Upland. For the Erzin-Agardag Fault, the rate of left-lateral displacement is 0.7–1.4 mm/yr and the age of strike-slip reactivation is estimated to be 2.1–1.1 Ma. For the Sayan-Tuva and Kaakhem faults, the minimum horizontal displacement rates are 0.9 ± 0.1 and 0.6 ± 0.1 mm/yr, and the maximum ages of the onset of strike-slip displacements are 2.4 Ma and 5 Ma, respectively. We propose that 1.1–2.1 Ma ago there was a kinematic change that activated left-lateral strike-slip faults, leading to the formation of the modern kinematic model, characterized by eastward movement of lithospheric blocks along inherited fault systems between the Hangay Dome and the Siberian Craton. Analysis of slip distribution and trenching across the Erzin-Agardag Fault allowed estimating the mean recurrence interval of the ∼ M7.8 earthquakes between 9.4 and 4.7 ka. The Erzin-Agardag Fault has produced multiple displacements with an amplitude of ∼ 6.6 m and follows a characteristic slip model.

萨彦-图瓦高原是中亚最北端的正地形，与印度-亚洲碰撞有关。它形成于中新世晚期至上新世早期的西伯利亚克拉通边界，以岩石圈块体的隆起和剪切位移为特征。在这项研究中，我们回答了萨彦-图瓦高原内部变形是如何分布的，以及水平位移的速率和年代等问题。通过形态构造和古地震学分析，我们计算了三个断层的位移速率和启动时间：它们是大型走向滑动断层系统的碎片，横贯整个萨彦-图瓦高原。对于 Erzin-Agardag 断层，左侧位移速率为 0.7-1.4 毫米/年，重新激活的走向滑动年龄估计为 2.1-1.1 马年。萨彦-图瓦断层和卡赫姆断层的最小水平位移速率分别为 0.9 ± 0.1 和 0.6 ± 0.1 毫米/年，走向滑动位移开始的最大年龄分别为 2.4 Ma 和 5 Ma。我们认为，1.1-2.1Ma前发生的运动变化激活了左侧走向滑动断层，导致现代运动模式的形成，其特征是岩石圈块体沿汉盖穹隆和西伯利亚克拉通之间的继承断层系统向东运动。通过对额尔津-阿格达格断层的滑动分布和沟槽分析，可以估算出 9.4 ka 至 4.7 ka 之间 M7.8 级地震的平均重现间隔。Erzin-Agardag 断层产生了振幅为 6.6 米的多次位移，并遵循一个特征滑动模型。

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引用次数: 0

Late Paleozoic to Mesozoic tectonic evolution of the Qinling Orogenic Belt: Structural and geochronological constraints from the Devonian Liuling Group, eastern Qinling area, China 秦岭造山带晚古生代至中生代构造演化：来自中国秦岭东部泥盆纪柳岭组的构造和地质年代约束

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-10-03 DOI: 10.1016/j.jseaes.2024.106349

Guoqing Jia, Jiahao Li, Wenhao Liu, Ming Guan, Chuanzhong Song

The Late Paleozoic to Mesozoic tectonic evolution of the Qinling Orogenic Belt is not fully understood. To address this, structural analysis and rutile U-Pb dating were performed on the Middle–Late Devonian Liuling Group located along the northern margin of the South Qinling Belt (SQB). Detailed structural analysis reveals that the Liuling Group experienced four main deformation events (D₁–D₄). Initial D₁ deformation is characterized by intrafolial folds (F₁) and a regional penetrative foliation (S₁). Subsequent D₂ is marked by SW-vergent asymmetric, overturned folds and related crenulation lineation (L₂). D₃ and D₄ are represented by, respectively, nearly E-W trending open folds and NNE-SSW trending centimeter-scale kink folds, both of which slightly modify D₁ and D₂ structures. Taking into account published chronological data, we propose that D₁ and D₂ occurred at 363–349 Ma and 332–318 Ma, respectively, and were associated with NE-SW oriented shortening during continental subduction of the SQB. Our new rutile U-Pb ages of 243–240 Ma provide a lower age limit for D₃ deformation, which was related to N-S oriented shortening triggered by continental collision between the South China Block (SCB) and SQB along the Mianlue Suture Zone (MLSZ). Finally, D₄ deformation was associated with the far-field effects of Late Jurassic subduction of the Paleo-Pacific Plate, which generated a WNW-ESE oriented shortening. Our findings suggest that continental subduction of the SQB continued until the earliest Late Carboniferous. Subsequently, the northern margin of the SQB experienced a Triassic metamorphic overprint triggered by collision between the SCB and SQB.

秦岭造山带晚古生代至中生代构造演化尚未完全清楚。为了解决这一问题，我们对位于南秦岭造山带北缘的中-晚泥盆世柳岭组进行了构造分析和金红石U-Pb年代测定。详细的构造分析表明，柳岭组经历了四次主要的变形事件（D1-D4）。最初的D1变形以片内褶皱（F1）和区域性穿透褶皱（S1）为特征。随后的 D2 变形的特征是西南向的不对称、翻转褶皱和相关的褶皱线（L2）。D3 和 D4 分别是近东西走向的开放褶皱和东北-西南走向的厘米级扭结褶皱，两者都对 D1 和 D2 结构略有改动。根据已公布的年代学数据，我们认为D1和D2分别发生于363-349 Ma和332-318 Ma，与SQB大陆俯冲过程中的NE-SW向缩短有关。我们新的金红石U-Pb年龄为243-240 Ma，为D3形变提供了一个年龄下限，D3形变与华南地块（SCB）和SQB沿绵鲁断裂带（MLSZ）的大陆碰撞引发的N-S向缩短有关。最后，D4形变与晚侏罗世古太平洋板块俯冲的远场效应有关，它产生了西北-东南走向的缩短。我们的研究结果表明，SQB的大陆俯冲一直持续到最早的晚石炭纪。随后，SQB 北缘经历了由 SCB 和 SQB 碰撞引发的三叠纪变质叠压。

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引用次数: 0

A review of the taxonomy, biostratigraphy and paleobiogeography of Plio-Pleistocene rhinoceroses in Japan 日本上新世犀牛的分类学、生物地层学和古生物地理学综述

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-10-03 DOI: 10.1016/j.jseaes.2024.106357

Naoto Handa, Keiichi Takahashi

The Rhinocerotidae were distributed in Eurasia and Africa during the late Neogene. In particular, the subtribe Rhinocerotina which includes the living species, diversified during the Plio-Pleistocene in Eurasia. Japan, which is situated in Far East Asia, has also yielded Plio-Pleistocene rhinocerotids, but their taxonomic position has not been revised since their first descriptions. Considering recent taxonomic revisions of many Eurasian Rhinocerotidae, it is necessary to also revise the Japanese remains. Here, taxonomy and fossil records of the Plio-Pleistocene Japanese rhinocerotids are reviewed. A total of 16 bones and teeth remains have been found from the mid-Pliocene to the middle Middle Pleistocene. Three Pliocene rhinocerotids are identified as Rhinocerotina gen. et sp. indet. In the earliest Pliocene, the close relative of the Japanese Pliocene rhinocerotid migrated from continental Asia. Stephanorhinus kirchbergensis was distributed in central to southwestern Japan during the middle Middle Pleistocene. In addition, indeterminate species were also present in the Early to Middle Pleistocene. The Late Pleistocene fossil record is uncertain due to the lack of stratigraphic and chronological data. Japanese S. kirchbergensis immigrated from the continental Asia (middle part of China) at ca. 0.65 Ma with a species of Stegodon together.

犀牛科动物在新近纪晚期分布于欧亚大陆和非洲。尤其是包括现生物种在内的犀牛亚目，在欧亚大陆的上新世时期就已经出现了多样化。位于远东亚洲的日本也发现了上新世的犀牛类，但自首次描述以来，其分类学地位尚未得到修订。考虑到最近对许多欧亚犀科动物的分类学修订，有必要对日本的犀科动物进行修订。本文回顾了上新世-更新世日本犀牛科的分类和化石记录。从上新世中期到中更新世中期，共发现了16块骨骼和牙齿遗迹。三个上新世的犀牛类被鉴定为犀牛属等。在上新世早期，日本上新世犀类的近亲从亚洲大陆迁徙而来。在中更新世中期，Stephanorhinus kirchbergensis分布于日本中部至西南部。此外，早更新世到中更新世还出现了不定种。由于缺乏地层和年代数据，晚更新世的化石记录尚不确定。日本的 S. kirchbergensis 于约 0.65 Ma 时从亚洲大陆（中国中部）移民而来。日本的S. kirchbergensis是在大约0.65Ma时从亚洲大陆（中国中部）移民过来的。

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引用次数: 0

Development of arcuate faults and controls on hydrocarbon accumulation in the Tiantai slope, Xihu Depression, East China Sea basin 东海盆地西湖凹陷天台斜坡弧形断层的发育及其对油气聚集的控制作用

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-10-03 DOI: 10.1016/j.jseaes.2024.106362

Lang Yu , Yixin Yu , Yiming Jiang , Wei Zou , Gongcheng Zhang , Xianjun Tang , Ting Tang , Xinxin Liang , Xinjian He , Dongxia Chen

The strike-slip movement of NW-trending transfer zone in the Tiantai slope of the Xihu Depression governed the development of the Cenozoic arcuate faults. These faults significantly influenced trap formation, sand-bodies distribution, and hydrocarbon migration. Based on seismic, drilling data and fault activity analysis methods, this paper describes the origin and evolution of the arcuate faults and their impact on hydrocarbon accumulation. These arcuate faults exhibit a change from NE to NW strike orientation in plan view, and are distributed in the hanging wall of the NW-trending basement faults. The main arcuate faults penetrate the bottom of the Cenozoic strata and extend upward through the top of the lower member of the Huagang Formation, markedly affecting the depositional dynamics of the Pinghu Formation. The segments of the arcuate faults began to grow during the Middle Eocene, and experienced hard linkages in the Late Eocene. The activity of these arcuate faults diminished significantly and gradually stopped during the Middle and Late Oligocene. The segmentation and linkage growth processes of the arcuate faults controlled the formation and evolution of traps. Additionally, the activities of these faults influenced the distribution of sandbodies, with the segmentation points of the arcuate faults serving as important conduits for sediment input. Moreover, the arcuate faults served as effective pathways for vertical hydrocarbon migration. The area with the arcuate faults present favorable conditions for hydrocarbon accumulation in the Tiantai slope of the Xihu Depression.

西湖凹陷天台斜坡西北向转换带的走向-滑动运动支配着新生代弧形断层的发育。这些断层对陷落的形成、砂体的分布和油气的迁移产生了重要影响。本文基于地震、钻井资料和断层活动分析方法，描述了弧形断层的起源、演化及其对油气聚集的影响。从平面图上看，这些弧形断层的走向由东北向变为西北向，分布在西北向基底断层的悬壁上。主要的弧曲断层穿透新生代地层底部，向上延伸至花岗岩层下统顶部，对平湖岩层的沉积动力学产生了明显影响。弧形断层的地段在中始新世开始生长，在晚始新世出现硬联系。这些弧形断层的活动在中更新世和晚更新世明显减弱并逐渐停止。弧形断层的分段和联结生长过程控制了陷落的形成和演化。此外，这些断层的活动还影响了沙体的分布，弧形断层的分段点成为沉积物输入的重要通道。此外，弧曲断层还是油气垂直迁移的有效通道。弧曲断层区域为西湖凹陷天台坡的油气聚集提供了有利条件。

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引用次数: 0

Tectonic evolution of the early Paleozoic intraplate orogen in the South China Block: Insights from Ductile Shear Zones in North Wuyishan 华南地块早古生代板内造山运动的构造演化：北武夷山韧性剪切带的启示

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-10-02 DOI: 10.1016/j.jseaes.2024.106343

WanLi Gao , ZongXiu Wang

The ductile shear zones within the North Wuyishan domain are key to understand the tectonic evolution of the South China Block (SCB). This study integrates a multifaceted approach, including field observations, thin section analysis, quartz electron backscatter diffraction (EBSD), zircon U-Pb dating, and mica ⁴⁰Ar/³⁹Ar dating, to elucidate the deformation history of these shear zones in North Wuyishan. The research identifies a two-stage deformation process of early Paleozoic. The initial D1 phase is marked by a top-to-SW thrusting shear, with associated felsic veins dated to the Ordovician period (447 ± 10 Ma to 459 ± 4 Ma), correlating with high-grade metamorphism and partial melting. The later D2 phase is characterized by NE-striking foliation and lineation, indicative of sinistral strike-slip shear, dated to the early Devonian (412 Ma) and early Carboniferous (∼354 Ma). The D1 phase suggests early crustal thickening and melting within the Cathaysia block, while D2 indicates a transpressional regime during post-orogenic adjustment. The geological features of the SCB, notably the absence of arc magmatism, ophiolitic mélange, and high-pressure metamorphism, comply with an intracontinental rift closure model as previously proposed. This model supports the hypothesis that the Early Paleozoic intracontinental orogeny in the SCB was likely a far-field consequence of a continental collision between the SCB-North Vietnam and South Vietnam blocks near the east Gondwana supercontinent.

北武夷山岩域内的韧性剪切带是了解华南地块构造演化的关键。本研究综合运用野外观测、薄片分析、石英电子反向散射衍射（EBSD）、锆石U-Pb定年和云母40Ar/39Ar定年等多种方法，阐明了北武夷山剪切带的变形历史。研究确定了古生代早期的两阶段变形过程。最初的 D1 阶段以自上而下向西的推覆剪切为特征，相关的长英岩脉可追溯到奥陶纪时期（447 ± 10 Ma 至 459 ± 4 Ma），与高级变质作用和部分熔融作用相关。较晚的 D2 阶段的特征是 NE-striking foliation 和 lineation，表明是 sinistral strike-slip shear，年代为泥盆纪早期（412 Ma）和石炭纪早期（∼354 Ma）。D1阶段表明早期地壳增厚和国泰沙洲地块内的熔融，而D2阶段则表明后成因调整期间的转位机制。SCB的地质特征，特别是没有弧岩浆活动、蛇绿混杂活动和高压变质活动，符合之前提出的大陆内部裂谷闭合模型。该模型支持这样的假设，即南中国海早古生代的大陆内造山运动很可能是南中国海-北越和南越地块在东冈瓦纳超大陆附近发生大陆碰撞的远场结果。

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引用次数: 0

Industrially induced warming triggered synchronous intensity changes in the East Asian summer and winter monsoons 工业导致的气候变暖引发了东亚夏季和冬季季风强度的同步变化

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-10-02 DOI: 10.1016/j.jseaes.2024.106351

Xuanqiao Liu , Xin Zhou , Liqiang Xu , Shiwei Jiang , Ming Ji , Luyao Tu , Xiaoyan Liu , Xiaolin Zhang

Anomalies in the East Asian monsoon system significantly disrupt the densely populated East Asian region, underscoring the importance of understanding such changes and improving current predictive abilities. On the basis of instrumental records, previous studies have shown that the East Asian winter monsoon (EAWM) and summer monsoon (EASM) interact with each other. However, owing to the lack of long-term high-resolution EAWM records, it remains unclear how and whether human activity has affected the phase relationship between the EASM and EAWM since the Industrial Revolution. In this study, we present a precisely dated high-resolution EAWM record for the last 300 years from a crater lake in northeastern China. Our results indicate that the EAWM intensity was relatively weak and fluctuated significantly between 1700 and 1850 CE. After 1850 CE, the EAWM strengthened rapidly and exceeded its intensity observed at the end of the Little Ice Age. In addition, a comparison of our reconstructed EAWM record with the published EASM record clearly shows in-phase variations during the Current Warm Period. We concluded that the climatic effects of industrially induced warming enhance the EAWM by slowing the Atlantic meridional overturning circulation and increasing the meridional temperature gradient, while also strengthening the EASM by increasing hemispheric meridional gradients and affecting other large-scale processes. Under the sustained intensification of human activity, the EASM and EAWM are likely to continue exhibiting synchronous variations in the future.

东亚季风系统的异常现象极大地扰乱了人口稠密的东亚地区，这凸显了了解这种变化并提高当前预测能力的重要性。根据仪器记录，以往的研究表明东亚冬季季候风和夏季季候风相互影响。然而，由于缺乏长期的高分辨率东亚冬季季候风记录，自工业革命以来，人类活动如何以及是否影响了东亚冬季季候风和夏季季候风之间的相位关系仍不清楚。在本研究中，我们从中国东北部的一个陨石坑湖中获得了过去 300 年中精确测定日期的高分辨率 EAWM 记录。我们的研究结果表明，在公元 1700 年至 1850 年期间，EAWM 强度相对较弱，且波动明显。西元 1850 年后，EAWM 迅速增强，并超过了小冰河时期末期观测到的强度。此外，将我们重建的 EAWM 记录与已公布的 EASM 记录进行比较，可以清楚地看到当前暖期的同相变化。我们得出的结论是，工业引起的气候变暖通过减缓大西洋经向翻转环流和增加经向温度梯度来增强 EAWM，同时也通过增加半球经向梯度和影响其他大尺度过程来加强 EASM。在人类活动持续加剧的情况下，EASM 和 EAWM 在未来可能会继续呈现同步变化。

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引用次数: 0

Dyke emplacement under mixed loading conditions: Insights from the Dharwar Craton, India 混合荷载条件下的堤坝形成：印度达瓦尔克拉通的启示

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-10-02 DOI: 10.1016/j.jseaes.2024.106359

Sirshendu Kumar Biswas, Tridib Kumar Mondal

Dykes are intrusive igneous bodies that play crucial role in the supply and ascent of magma to the Earth’s crust. Magma can intrude along pre-existing anisotropies such as fractures or foliations present within the host rock or it may create its own path by fracturing the host rock. In the latter scenario, when fractures are formed by the pressure exerted by the invading magma, a dyke’s outcrop shape and geometry are diagnostic of the conditions under which it evolved. Here, we report mafic dykes emplaced within the younger granites of Dharwar Craton, peninsular India. Outcrop attributes of these dykes are characteristic of emplacement under conditions of mixed mode loading. We discuss different discrete modes of fracture formation and their possible combinations to understand the generation and eventual emplacement of dykes under mixed mode loading. This leads to the development of a comprehensive sequence of progressive dyke evolution under mixed mode I-III loading and thereby distinguishing incremental orders of dyke horn formation. We further apply this knowledge along with collected field evidence on dyke body geometries to propose an evolutionary model of dyke formation and emplacement within the Chitradurga granite under varying regional stress fields of the Chitradurga Schist Belt, Western Dharwar Craton, India. We infer, that the dykes initiated as extensional fractures within an earlier NE-SW directed compressive stress field and were subsequently sheared sinistrally by the effect of the adjacent Chitradurga Shear Zone on account of a later E-W to ESE-WNW directed compression.

堤坝是侵入性火成岩体，在岩浆向地壳的供应和上升过程中起着至关重要的作用。岩浆可以沿着宿主岩内部存在的断裂或叶状体等原有的异向性侵入，也可以通过断裂宿主岩来创造自己的路径。在后一种情况下，当侵入的岩浆施加压力而形成裂缝时，堤坝的露头形状和几何特征就能诊断出其演化的条件。在此，我们报告了位于印度半岛达瓦尔克拉通较年轻花岗岩中的岩浆岩堤。这些堤坝的露头特征是在混合模式加载条件下形成的。我们讨论了断裂形成的不同离散模式及其可能的组合，以了解混合模式加载条件下堤坝的生成和最终移位。这导致了在混合模式 I-III 荷载下堤坝逐步演化的综合序列的发展，从而区分了堤坝角形成的递增顺序。我们进一步应用这些知识以及收集到的关于堤体几何形状的实地证据，提出了印度西达尔瓦克拉通奇特拉杜尔加片岩带不同区域应力场下奇特拉杜尔加花岗岩内堤坝形成和置换的演化模型。我们推断，堤坝最初是在早期东北-西南向压缩应力场中的延伸断裂，随后在邻近的奇特拉都加剪切带的作用下被正向剪切，形成了后来的东-西至东-西-西北向压缩应力场。

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引用次数: 0

Reworking of a Caledonian (Early Paleozoic) granodiorite porphyry in a collisional zone in South China and its contribution for tungsten mineralization 华南碰撞带加里东期（早古生代）花岗闪长岩斑岩的重整及其对钨矿化的贡献

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-10-02 DOI: 10.1016/j.jseaes.2024.106356

Wen-Jing Mao , Yi-Qu Xiong , Yong-Jun Shao , Matthew J. Brzozowski , Qiang He , Hong-Fei Di , Zhi-Wei Fan , Yu-Jie Mao , Wen-Jie Fang

A newly discovered ore-bearing granodiorite porphyry in the Chuankou tungsten (W) ore field is the largest W deposit formed during the Indosinian (Triassic) collision event in South China. As such, its genesis and relationship to W mineralization in the region remains ambiguous. Zircon U–Pb dating demonstrates that the Chuankou granodiorite porphyry was emplaced at 436.1 ± 0.8 Ma, predating the Triassic W mineralization in the ore field. The granodiorite porphyry is characterized by low Zr + Nb + Ce + Y concentrations (100–294 ppm), 10000 Ga/Al values (2.09–2.62), indicating that it is a weakly fractionated I-type granite. Variably negative ε_Hf(t) values of −10.2 to −2.48 and T_DM2 values of 2.06–1.06 Ga suggest crystallization from a partial melt of amphibolite, with minor contributions of metasedimentary rock in the middle–lower crust during the Caledonian collisional event. Given its low degrees of differentiation, the Chuankou granodiorite porphyry is inferred to have low mineralization potential. The presence of abundant fluorite in the granodiorite porphyry, coupled with elevated whole-rock F contents (0.4–4.1 wt%), suggests that volatile (F) involvement in Indosinian W mineralization might partially originate from the Caledonian granodiorite porphyry. Furthermore, the elevated whole-rock W contents, which exceeds those of granites related to W mineralization from regional (including Indosinian granites in the Chuankou W ore field), and other regions worldwide, indicate that W in the granodiorite porphyry was likely added to the ore-forming fluids during Indosinian magmatic–hydrothermal events. Consequently, we infer that W in the Caledonian Chuankou granodiorite porphyry was mobilized by F-rich fluids and potentially served as a partial source for the Indosinian mineralization.

川口钨（W）矿区新发现的含矿花岗闪长岩斑岩是华南地区印支期（三叠纪）碰撞事件中形成的最大的W矿床。因此，它的成因以及与该地区钨矿化的关系仍然模糊不清。锆石U-Pb年代测定表明，川口花岗闪长岩斑岩形成于436.1 ± 0.8 Ma，早于该矿区三叠纪W矿化。花岗斑岩的特征是 Zr + Nb + Ce + Y 浓度低（100-294 ppm）、10000 Ga/Al 值低（2.09-2.62），表明它是弱分馏的 I 型花岗岩。εHf(t)值为-10.2至-2.48的不同负值，TDM2值为2.06-1.06 Ga，表明它是由闪长岩的部分熔体结晶而成，在加里东碰撞事件中，中下地壳的玄武岩也有少量参与。鉴于川口花岗闪长岩斑岩的分化程度较低，推断其成矿潜力较低。花岗闪长斑岩中存在丰富的萤石，加上全岩萤石含量较高（0.4-4.1 wt%），这表明印支期W矿化中的挥发物（萤石）可能部分来源于加里东花岗闪长斑岩。此外，全岩W含量较高，超过了区域（包括川口W矿田中的印支期花岗岩）和世界其他地区与W成矿有关的花岗岩，这表明花岗斑岩中的W很可能是在印支期岩浆-热液事件中添加到成矿流体中的。因此，我们推断加里东川口花岗闪长岩斑岩中的W是被富含F的流体动员起来的，并有可能成为印支期成矿作用的部分来源。

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Detrital clay mineral input reconstructed based on weathering records and its influence on organic matter enrichment: A case study of the Paleogene Shahejie Formation in the Dongpu Sag, Bohai Bay Basin 基于风化记录重建的粘土矿物输入及其对有机质富集的影响：渤海湾盆地东蒲沙格古近纪沙河街地层案例研究

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2024-10-02 DOI: 10.1016/j.jseaes.2024.106360

Rusi Zuo , Jingong Cai , Xiang Zeng , Shi Cheng

As major components of shales, clay minerals are important for investigating unconventional petroleum geology. However, there are few quantitative methods for investigating possible inputs of clay minerals during sedimentary processes. In this study, shales from the Shahejie Formation in the Dongpu Sag, Bohai Bay Basin, were chosen for investigating clay mineral inputs. The shales are abundant in a variety of clay minerals. The shales, uniformly derived from felsic igneous rocks, underwent mild K metasomatism. Thus, the detrital clay mineral input was primarily influenced by weathering intensity. Accordingly, representative samples subjected to varying weathering intensities were selected to identify detrital and diagenetic clay minerals. Kaolinite and chlorite are of detrital origin. Illite and illite/smectite mixed layers (I/S) have both detrital and diagenetic origins. The precursor minerals of diagenetic minerals can be identified based on their morphological and elemental characteristics. After quantifying the area proportions of various clay minerals, the detrital clay mineral compositions of selected samples were calculated. Further analysis indicated that the detrital illite content and the detrital chlorite content are closely related, while the detrital smectite content correlates well with the chemical index of alteration (CIA). Based on the preceding analysis, the fitting formulas were established to quantitatively characterize the input of detrital clay minerals. The shales from the north sag had a high input of detrital smectite, whereas the shales from the south sag had a high input of detrital illite. Consequently, the shales from the north sag contain more organic matter than those from the south sag.

粘土矿物是页岩的主要成分，对研究非常规石油地质非常重要。然而，目前很少有定量方法来研究沉积过程中粘土矿物的可能输入。本研究选择了渤海湾盆地东濮下陷沙河街地层的页岩来研究粘土矿物的输入。这些页岩富含多种粘土矿物。这些页岩均来源于火成岩，经历了温和的 K 变质作用。因此，碎屑粘土矿物的输入主要受风化强度的影响。因此，我们选取了不同风化强度的代表性样本，以鉴定碎屑和成岩粘土矿物。高岭石和绿泥石属于脱盐矿物。伊利石和伊利石/直闪石混合层（I/S）既源于脱盐，也源于成岩。成岩矿物的前体矿物可根据其形态和元素特征进行识别。在对各种粘土矿物的面积比例进行量化后，计算出了所选样本的碎屑粘土矿物成分。进一步的分析表明，残积伊利石含量和残积绿泥石含量密切相关，而残积闪长岩含量与蚀变化学指数（CIA）有很好的相关性。在上述分析的基础上，建立了拟合公式，以定量表征脱盐粘土矿物的输入。北矢状岩的页岩含有大量的非晶质闪石，而南矢状岩的页岩则含有大量的非晶质伊利石。因此，北陡崖页岩比南陡崖页岩含有更多的有机物。

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