Structure and deformation around the Gyirong basin,north Himalaya,and onset of the south Tibetan detachment system |
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Authors: | XiongYing?Yang Email author" target="_blank">JinJiang?ZhangEmail author GuoWei?Qi DeChao?Wang Lei?Guo PengYuan?Li Jiang?Liu |
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Institution: | (1) The Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education; School of Earth and Space Sciences, Peking University, Beijing, 100871, China |
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Abstract: | Gyirong basin and its adjacent area are located at a special position in the Himalayan orogen, where the south Tibetan detachment
system (STDS) and N-S trending rift converged. The north Himalayan orogen here can be divided into five petrologic-tectonic
units successively from south to north: 1) the Greater Himalayan crystalline complex (GHC); 2) the STDS shear zone; 3) the
Tethyan Himalayan sedimentary sequence (THS); 4) the late Cenozoic sedimentary basins, such as Gyirong and Oma basins; and
5) the Malashan gneiss dome. Structural studies show that this area experienced four stages of deformation: 1) the earlier
south-directed thrusting, preserved both in the GHC and THS; 2) top-down-to-north slip along the STDS, normal faults related
to this slip formed the early controlling structures of the Cenozoic basins, and the tilted pattern of the blocks between
the basins indicated a north-directed slip; 3) east-west extension, the resultant N-S trending normal fault formed the eastern
boundary of the basins; and 4) late gravitational collapse. Zircon SHRIMP U-Pb dating on the syn-deformational (leuco-) granite
along the STDS indicates that the major activity of the STDS occurred at ca. 26 Ma, but its onset may have begun as early
as ca. 36 Ma.
Supported by National Natural Science Foundation of China (Grant Nos. 40821002, 40572115) |
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Keywords: | south Tibetan detachment system (STDS) deformation stage syn-deformational granite zircon SHRIMP U-Pb dating onset age |
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