| 武陵—江南造山带中段地壳结构及其物质组成差异——基于地球化学和地球物理异常特征研究 |
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| 关键词:Jiangnan Orogenic Belt Jurassic fold north–south gravity gradient belt western Hunan–western Hubei Metallogenic Belt deep structure |
| 基金项目:中国地质调查局地质调查项目(编号: DD20190012; DD20221643);国家自然科学基金项目(编号: 41630320; 42074099; 42174092);自然资源部深地动力学重点实验室自主(开放)研究课题(编号: J1901-16) |
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| Differences in Crustal Structure and Composition in Wuling–Middle Part of Jiangnan Orogenic Belt: Based on Geochemical and |
| Regional deep structures and bulk crustal compositions are associated with mineralization and oil and gas accumulation and contribute to their preservation. The western part of the Wuling–Jiangnan orogenic belt represents an important petroliferous basin in China, while the central and eastern parts are characterized by an abundance of metals such as lead and zinc. Here, we investigate the geochemical and geophysical anomalies to elucidate the geodynamic background controlling the variation in crustal structure and composition of the Wuling–Jiangnan orogenic belt. We show substantial spatial variations in composition and element enrichment using geochemical cluster analysis and suggest that this may be related to certain structures deep in the crust. Regional geophysical studies (gravity, magnetic, and seismic) show a thrust-related chevron-type syncline zone in the east and a large-scale detachment in the middle and lower crust. While in the west, there are only thrust-related chevron-type anticlines in the upper crust. A north–south gravitational gradient belt is observed through the southeastern region, which divides the study area into two parts. There are substantial differences in crustal structure, thickness, composition, deformation, and topography. Variations in geophysical properties show that the tectonic evolution of the eastern side of the gravitational gradient belt is primarily affected by the westward subduction of the paleo-Pacific and its far-field stress, which is related to a geodynamic compressional–extensional background transition. This transition may be caused by the retreat and (or) change in the angle or direction of subduction during the Late Mesozoic. A comprehensive geochemical and geophysical study shows that the interaction of different geological units provides favorable conditions for forming the western Xiang(Hunan)-E(Hubei) metallogenic belt. High-value geochemical anomalies are distributed at the boundary of the metallogenic belt, where the Qiyueshan fault and Jiangnan orogenic belt are suggested as exploration prospects. Future studies will include continued investment in comprehensive geochemical and geophysical interpretation and provide further constraints for regional tectonic deformation, evolution, and metallogenic processes. |
| CHEN Chang-xin,YAN Jia-yong,LIU Wei-qiang,LUO Fan,ZHANG Chong,XU Yao,CHENG Zhi-zhong,WANG Yang.2022.Differences in Crustal Structure and Composition in Wuling–Middle Part of Jiangnan Orogenic Belt: Based on Geochemical and[J].Acta Geoscientica Sinica,43(6):785-802. |
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