| 二维初至波层析成像揭示的兰坪盆地—扬子西缘浅层地壳结构 |
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| 引用本文：王冠,熊小松,卢占武,李秋生,吴国炜,张新彦.2024.二维初至波层析成像揭示的兰坪盆地—扬子西缘浅层地壳结构[J].地球学报,45(6):989-1001. |
| DOI：10.3975/cagsb.2024.040101 |
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| 基金项目:国家重点研发计划(编号: 2016YFC0600302)；国家自然科学基金项目(编号: 42374119; 42261144669; 42274134; C2330)；中国地质科学院基本科研业务费项目(编号: S2304; JKYQN202311) |
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| 中文摘要:兰坪盆地—扬子西缘位于青藏高原东南缘, 在地质构造上属特提斯-喜马拉雅强烈挤压、碰撞造山带的东部, 兼跨华南板块与古冈瓦纳板块两大构造单元。其浅层地壳是记录地壳形变、岩浆作用与成矿作用的重要载体。本文利用兰坪盆地—扬子西缘220 km长的深反射地震剖面的初至波(Pg震相)数据, 通过层析成像反演方法, 获得了测线下方4 km以浅的上地壳浅层P波速度结构。成像结果显示, 兰坪盆地沉积厚度从西到东逐渐减薄, 扬子块体西缘东部表现出“两侧厚中间薄”的特点; 兰坪盆地内有多组逆冲断裂, 金沙江断裂与程海断裂近乎垂直; 金顶铅锌矿的形成可能与底部热隆有关, 北衙金矿下方结晶基底向上突起, 推测由岩浆上涌所致。 |
| 中文关键词:兰坪盆地 扬子块体西缘 层析成像 上地壳速度结构 |
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| Shallow Crustal Velocity Structure of the Lanping Basin–Western Margin of the Yangtze Block Revealed by 2D First-arrival Seismic Tomography |
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| Abstract:The Lanping Basin–western margin of the Yangtze block, located in the southeastern margin of the Tibetan Plateau, geotectonically belongs to the eastern part of the Tibetan-Himalayan collision orogenic belt. It spans two major tectonic units (the South China block and the Gondwana). The shallow crust is an important carrier for recording crustal deformation, magmatism and mineralization.. In this study, we obtain the shallow P-wave velocity structure of the upper crust by using the first-arrivals (Pg phase) from a 220-km-long deep-reflection seismic profile. The result shows that the sedimentary thickness of the Lanping Basin gradually decreases from west to east, and the eastern part of the western margin of the Yangtze block exhibits characteristics of “thick on both sides and thin in the middle”. Several thrust faults were developed in the Lanping Basin. The Jinshajiang and Chenghai faults are steep in the shallow upper crust. Formation of the Jinding Pb-Zn deposit may be associated with the deep thermal. The crystalline basement beneath the Beiya Au deposit bulges upward, which is speculated to be caused by the upwelling magma. |
| keywords:Lanping Basin western margin of the Yangtze block seismic tomography shallow crustal velocity structure |
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