Neotectonics of the Eastern Margin of the Tibetan Plateau: New Geological Evidence for the Change from Early Pleistocene Transpression to Late Pleistocene-Holocene Strike-slip Faulting |
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| Authors: | ZHANG Yueqiao LI Hailong LI Jian |
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| Institution: | 1. School of Earth Sciences and Engineering, Nanjing University, China;2. Key Laboratory of Neotectonic Movement and Geohazard, Ministry of Land and Resources, China;3. Institute of Geomechanics, Chinese Academy of Geological Science, China |
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| Abstract: | We present in this paper some new evidence for the change during the Quaternary in kinematics of faults cutting the eastern margin of the Tibetan Plateau. It shows that significant shortening deformation occurred during the Early Pleistocene, evidenced by eastward thrusting of Mesozoic carbonates on the Pliocene lacustrine deposits along the Minjiang upstream fault zone and by development of the transpressional ridges of basement rocks along the Anninghe river valley. The Middle Pleistocene seems to be a relaxant stage with local development of the intra‐mountain basins particularly prominent along the Minjiang Upstream and along the southern segment of the Anninghe River Valley. This relaxation may have been duo to a local collapse of the thickened crust attained during the late Neogene to early Pleistocene across this marginal zone. Fault kinematics has been changed since the late Pleistocene, and was predominated by reverse sinistral strike‐slip along the Minshan Uplift, reverse dextral strike‐slip on the Longmenshan fault zone and pure sinistral strike‐slip on the Anninghe fault This change in fault kinematics during the Quaternary allows a better understanding of the mechanism by which the marginal ranges of the plateau has been built through episodic activities. |
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| Keywords: | Quaternary transpression strike‐slip faulting eastern margin of the Tibetan Plateau Minjiang upstream fault back Longmenshan fault Anninghe faulted valley |
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