Paleomagnetic versus GPS determined tectonic rotation around eastern Himalayan syntaxis in East Asia |
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| Institution: | 1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;2. Key Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;3. Institutions of Earth Science, Chinese Academy of Sciences, Beijing 10029, China;4. Jiangxi Earthquake Administration, Nanchang 330039, China;1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China;2. State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences and Resources, Research Center for Tibetan Plateau Geology, China University of Geosciences (Beijing), Beijing 100083, China;3. State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China;4. Center for Study of Imaging and Dynamics of the Earth, Institute of Geophysics and Planetary Physics, University of California, Santa Cruz, CA 95064, USA;5. Graduate University of Chinese Academy of Sciences, Beijing 100049, China;6. Liaoning Non–Ferrous Geological Exploration Institute, Shenyang 110013, China;7. University of Houston, 4800 Calhoun Rd, Houston, TX 77004, USA |
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| Abstract: | Northward indentation of the Indian Plate has brought about significant tectonic deformation into East Asia. A record of long-term tectonic deformation in this area for the past 50 M yr, particularly the vertical axis rotation, is available through paleomagnetic data. In order to depict rotational deformation in this area with respect to Eurasia, we compiled reliable paleomagnetic data sets from 79 localities distributed around eastern Himalayan syntaxis in East Asia. This record delineates that a zone affected by clockwise rotational deformation extends from the southern tip of the Chuan Dian Fragment to as far as the northwestern part of the Indochina Peninsula. A limited zone that experienced a significant amount of clockwise rotation after an initial India–Asia collision is now located at 23.5°N, 101°E, far away from an area (27.5°N, 95.5°E) where an intense rotational motion has been viewed by a snapshot of GPS measurements. This discrepancy in clockwise rotated positions is attributed to southeastward extrusion of the tectonic blocks within East Asia as a result of ongoing indentation of the Indian Plate. A quantitative comparison between the GPS and paleomagnetically determined clockwise rotation further suggests that following an initial India–Asia collision the crust at 30°N, 94°E paleoposition was subjected to southeastward displacement together with clockwise rotation, which eventually reached to present-day position of 23.5°N, 101°E, implying a crustal displacement of about 1000 km during the past 50 M yr. |
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