Exhumation history and faulting activity of the southern segment of the Longmen Shan,eastern Tibet |
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| Institution: | 1. Department of Earth Sciences and Institute of Energy Sciences, Nanjing University, Nanjing 210093, China;2. Resources and Environment Institute, Southwest Petroleum University, Chengdu 610500, China;3. The Southwest Branch of SINOPEC, Chengdu 610016, China;1. Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, P.O. Box 9825, Beijing 100029, China;2. Key Laboratory of Digital Earth Sciences, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100094, China;1. Aix-Marseille Université (AMU), IRD, CNRS, CEREGE UM34, BP 80, 13545 Aix-en-Provence, Cedex 4, France;2. Grenoble Alpes Université, CNRS, UMR 5275, ISTerre, 38041 Grenoble, Cedex 9, France;3. Laboratoire de Géologie, Ecole Normale Supérieure, Paris, France;4. Institute of Geology, China Earthquake Administration, Beijing 100029, China;5. Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China |
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| Abstract: | The Longmen Shan (LMS), which constitutes the eastern border of the Tibetan Plateau, is about 400 km in length and characterized by a steep topographic transition from the Sichuan Basin to the plateau. The 2008 Mw7.9 Wenchuan earthquake and 2013 Mw6.6 Lushan earthquake were associated with the central to northern segments and southern segment of the LMS fault belt, respectively. In this paper, zircon and apatite fission track (ZFT and AFT, respectively) dating in combination with previously published low temperature thermochronology studies are used to constrain both the exhumation history and fault activity along the LMS, with a special focus on the southern segment. In the southern segment of the LMS, the ZFT ages in the hanging wall of the Wulong-Yanjing fault 10–14 Ma, increasing to ca. 30 Ma to the northwest of the faults and to 100–200 Ma in the plateau region. The AFT ages are 3–5 Ma at the mountain front and increase to 8–26 Ma in the plateau. We show that these age distributions are controlled by fault geometry. Two stages of rapid exhumation were identified using apatite fission track length modeling and the age distributions in the southern segment of the LMS. The first stage is from ca. 30 Ma and the second stage is from 3–5 Ma to present. In contrast with the middle segment of the LMS, the Cenozoic exhumation rate is higher in the southern segment of the LMS, which may be due to the influence of the collision between the India and Eurasia plates and/or different faulting mechanisms in the different segments. |
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| Keywords: | Eastern Tibet Longmen Shan Exhumation history Low temperature thermochronology Fission track |
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