Seismic structure beneath the Tibetan Plateau from iterative finite-frequency tomography based on ChinArray: New insights into the Indo-Asian collision
Seismic structure beneath the Tibetan Plateau from iterative finite-frequency tomography based on ChinArray: New insights into the Indo-Asian collision
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基于 ChinArray 的迭代有限频率层析成像研究青藏高原下方的地震结构：对印度-亚洲碰撞的新见解
DOI：
10.1029/2019jb018344
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Liu Q
中科院分区：
文献类型：
--
作者：
Xiao Z;Fuji N;Iidaka T;Gao Y;Sun X;Liu Q
青藏高原是新生代以来全球最显著的隆升之一，印度-亚洲大陆碰撞对青藏高原的生长起了重要作用。地壳和上地幔结构是理解高原演化过程和横向生长的关键因素。我们提出了一个新的青藏高原及其周边地区的三维地震模型，该模型使用了迭代有限频率层析成像的大规模密集阵列。新的层析成像图像显示了西藏地下高速异常导致的印度岩石圈向北明显的东西向几何变化。高速异常在西侧延伸至帕米尔高原，但仅到达西藏中东部的拉萨北部。加厚的西藏岩石圈的对流移动被观察到作为一个高速异常，随后是印度地幔岩石圈在西藏中部班公湖-怒江缝合带下的近垂直俯冲。我们推测它与中新世晚期广泛的岩浆活动和西藏中部的快速隆升有关。龙门山断裂下方100 ~ 250 km处的高速空区表明，岩石圈拆沉作用可能在藏东地区与周边刚性块体之间的地表演化中起着重要作用。我们详细的地震学模型将让我们深入了解大陆是如何碰撞的。
Indo‐Asian continental collision has contributed to the growth of the Tibetan Plateau, which is one of the most prominent uplifts worldwide since Cenozoic. The crustal and upper‐mantle structures are key factors in understanding the evolutionary process as well as lateral growth of the plateau. We present a new 3‐D seismic model beneath the Tibetan Plateau and its surrounding areas, which uses a large‐scale dense array from iterative finite‐frequency tomography. The new tomographic images show obvious east‐west geometrical change of the northward Indian lithosphere by high‐velocity anomalies beneath Tibet. The high‐velocity anomaly extends to Pamir in the western side, but it only reaches north Lhasa in central and eastern Tibet. A convective removal of the thickened Tibetan lithosphere is observed as a high‐velocity anomaly, followed by a subvertical subduction of the Indian mantle lithosphere beneath the Bangong‐Nujiang Suture in central Tibet. We speculate its link to the widespread magmatism and rapid uplift of central Tibet in late Miocene. A high‐velocity gap between 100 and 250 km underneath the Longmenshan fault indicates that lithospheric delamination may play an important role in surface evolution between eastern Tibet and surrounding rigid blocks. Our detailed seismological model will give an insight into how the continents collide.