Crust and Upper Mantle Density Structures beneath the Eastern Tianshan Region and Its Tectonic Implications  

作　　者：Yiming Liu Chao Chen Qing Liang Zhengwang Hu 

机构地区：[1]Hubei Subsurface Multi-Scale Imaging Key Laboratory,School of Geophysics and Geomatics,China University of Geosciences,Wuhan 430074,China

出　　处：《Journal of Earth Science》2024年第3期828-838,共11页地球科学学刊（英文版）

基　　金：supported by the National Natural Science Foundation of China(No.41774091).

摘　　要：The deformation mechanisms of the Tianshan orogenic belt(TOB)are one of the most important unresolved issues in the collision of the Indian and Eurasian plates.To better understand the lithospheric deformation of the eastern Tianshan orogenic belt,we combined the S-wave tomography and gravity data to develop a three-dimensional(3D)density model of the crust and upper mantle beneath the eastern Tianshan area.Results show that the crust of the eastern Tianshan is mainly characterized by positive density anomalies,revealing widespread subduction-related magmatism during the Paleozoic.We however have also observed extensive low-density anomalies beneath the eastern Tianshan at depths deeper than~100 km,which is likely linked to a relatively hot mantle.The most fundamental differences of the lithosphere within the eastern Tianshan occur in the uppermost mantle.The uppermost mantle layers in the Bogda Shan and Harlik Shan are relatively dense.This is likely associated with an eclogite body in the uppermost mantle.The most significant negative anomaly of the uppermost mantle is however found in the Jueluotage tectonic belt and the central Tianshan Block and is possibly associated with depleted mantle material.We suggest that these differences related to compositional changes may control the strength of the lithospheric mantle and have affected the uplift of the northern and southern segments of the eastern Tianshan after the Permian.

关 键 词：constrained inversion gravity anomaly three-dimensional lithospheric density structure eastern Tianshan GEODYNAMICS geophysics. 

分 类 号：P54[天文地球—构造地质学]