• ISSN 2097-1893
  • CN 10-1855/P
吴国炜,熊小松,高锐,陈宣华,李英康,王冠,任海东. 2023. 宽角反射/折射剖面揭示的祁连造山带莫霍面深度. 地球与行星物理论评(中英文),54(2):109-119. DOI: 10.19975/j.dqyxx.2021-067
引用本文: 吴国炜,熊小松,高锐,陈宣华,李英康,王冠,任海东. 2023. 宽角反射/折射剖面揭示的祁连造山带莫霍面深度. 地球与行星物理论评(中英文),54(2):109-119. DOI: 10.19975/j.dqyxx.2021-067
Wu G W, Xiong X S, Gao R, Chen X H, Li Y K, Wang G, Ren H D. 2023. Moho depth of the Qilian orogen revealed by wide-angle reflection/refraction profiles. Reviews of Geophysics and Planetary Physics, 54(2): 109-119 (in Chinese). DOI: 10.19975/j.dqyxx.2021-067
Citation: Wu G W, Xiong X S, Gao R, Chen X H, Li Y K, Wang G, Ren H D. 2023. Moho depth of the Qilian orogen revealed by wide-angle reflection/refraction profiles. Reviews of Geophysics and Planetary Physics, 54(2): 109-119 (in Chinese). DOI: 10.19975/j.dqyxx.2021-067

宽角反射/折射剖面揭示的祁连造山带莫霍面深度

Moho depth of the Qilian orogen revealed by wide-angle reflection/refraction profiles

  • 摘要: 祁连造山带位于青藏高原东北缘,距南侧的喜马拉雅碰撞带前缘1500 km,以一个宽阔的(东西长约1000 km,南北宽200~400 km)、NW走向的造山带的形式被夹持于北侧的河西走廊盆地与南侧的柴达木盆地之间,西侧被NEE走向的阿尔金左行走滑断裂带所截切,北缘以青藏高原北缘断裂带,祁连山北缘断裂带和祁连山东缘断裂带与河西走廊盆地相邻,南东方向与西秦岭造山带相接,东缘与鄂尔多斯地块相邻. 记录了新生代以来印度板块和亚洲大陆板块碰撞和青藏高原边缘造山和地壳变形的重要过程. 对其地壳深部结构的探测是研究青藏高原隆升和向北扩展,理解印度与欧亚大陆碰撞的大陆内部构造作用的关键手段. 自1980年代以来,前人在研究区实施了多条宽角反射/折射剖面,以揭示祁连造山带及周缘的地壳深部结构. 本文通过对这些宽角反射/折射剖面的收集汇总和梳理分析,以探讨祁连造山带不同区段下方莫霍面起伏及深度差异,研究结果显示:祁连造山带莫霍面埋深整体自西向东变浅,最深的莫霍面位于北祁连造山带内的哈拉湖附近;结合其他地质与地球物理资料,本文推测莫霍面深度的起伏及变化状态揭示了祁连造山带由西向东不同的地壳缩短方式,其中西段最深的莫霍面可能由大陆俯冲的“底垫作用”所引起;中段的壳内低速体和低阻体反映了该区上下地壳解耦变形,地壳的持续缩短主要靠变形解耦面以上发育的大型逆冲断裂带调节;而莫霍面深度最浅的东段累积应力则主要靠左行走滑的海原断裂和壳内发育的逆冲断裂调节.

     

    Abstract: The Qilian Orogenic Belt is located on the northeastern edge of the Qinghai-Tibet Plateau, 1500 km  far  from the front of the Himalayan collision zone to the south, manifesting as an orogenic belt with a NW orientation between the Alxa Block to the north and the Qaidam Block to the south (approximately 1000 km long from east to west and 200~400 km wide from north to south). It is truncated by the NE-trending Altyn left-lateral strike-slip fault to the west and surrounded by the northeastern Tibetan Plateau, Qilian Mountain, and Hexi Corridor to the north. To the southeast, it is connected to the west Qinling orogenic belt, and the eastern margin is adjacent to the Ordos Block. It has played an important role in the collisional process between the Indian and Asian continental plates, and the mountain-building of the Qinghai-Tibet Plateau since the Cenozoic. Exploration of the deep structure of the crust is key to study the uplift and northward expansion processes of the Qinghai-Tibet Plateau and understand the intracontinental deformation caused by the collision between India and Eurasia plates. In this study we integreted the wide-angle reflection/refraction profiles conducted in this area since the 1980s and summarizes the outcome of the Moho depth. The results show that the Moho becomes shallower from west to east as a whole, and the deepest Moho in the west section, which may be induced by the continental two-way subduction and underplating. In the central section, the low-velocity anomalies with high conductivity are well developed, which may present the decollement in the crust, and the crustal deformation was mainly accommodated by the overthrusting in the upper crust. whereas the crustal deformation is released by the large-sccale-lateral strike-slip faults.

     

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