Earth Science Frontiers ›› 2022, Vol. 29 ›› Issue (4): 221-230.DOI: 10.13745/j.esf.sf.2022.4.66

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Crustal structure of the Cona rift, eastern Himalaya

WU Jiajie1,2(), XU Xiao1,2,*(), GUO Xiaoyu1,2, LU Zhanwu3, WU You1,2, XIANG Bo1,2, YU Yang1,2, LI Chunsen1,2, YU Jiahao1,2, TONG Xiaofei1,2, LUO Xucong1,2   

  1. 1. School of Earth Sciences and Engineering, Sun Yat-sen University, Zhuhai 519082, China
    2. Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082, China
    3. Institute of Geology, Chinese Academy of Geological Sciences, Beijing, 100037, China
  • Received:2022-04-25 Revised:2022-04-30 Online:2022-07-25 Published:2022-07-28
  • Contact: XU Xiao

Abstract:

The Himalayan mountain range is the result of continental-continental collision between the Indian and Eurasian plates. It has been under great debate as to why the rifts of southern Tibet are formed at the front of the collision zone. To answer this question, it is necessary to understand the crustal structure of the rifts. The age of each rift zone tends to be younger from west to east. In this study, we revealed the crustal structure of the Cona rift, a relatively young continental rift, using the P-wave receiver function calculated from teleseismic data received by a dense array across the rift, and analyzed the rift formation process based on the crustal structure. We showed that the Cona rift is a crustal-scale rift, where Moho offsets beneath the rift and significant lateral variations develops. We suggest that the formation of the rifts may be associated with regional tectonic activities, and further studies are needed to ascertain whether a single gravity collapse can form crustal-scale rifts. Based on the previous studies of magmatic rocks and geophysical observations, we infer that the asthenospheric upwelling caused by tearing of the subducting Indian plate weakened the lower crust of the Cona rift region where the middle and upper crust is also weakened as shown by the study of Himalayan leucogranites. Considering all the study results, we hypothesize that the formation of crustal-scale rift requires crustal weakening at different depths.

Key words: Cona rift, short-period dense array, receiver function, crustal weakening

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