Crustal structure in the Tengchong volcanic area and position of the magma chambers |
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| Institution: | 1. Department of Geology and Geography, Auburn University, Auburn, AL 36849, USA;2. High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC), Department of Geosciences, National Taiwan University, Taipei, Taiwan, ROC;3. Institute of Geology, China Earthquake Administration, Beijing 100029, China;1. State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Science and Resources, China University of Geosciences, Beijing 100083, China;2. CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China;1. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China;2. Yunnan Institute of Geological Survey, Kunming 650051, China;1. State Key Laboratory of Biogeology and Environmental Geology, Laboratory of Basin Hydrology and Wetland Eco-restoration, School of Environmental Studies, China University of Geosciences, 430074 Wuhan, Hubei, PR China;2. Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany |
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| Abstract: | In this paper, we extract 1500 P receiver functions in the Tengchong volcanic area from 211 teleseismic events recorded at nine digital seismic stations. A common conversion point stacking technique is used to improve the signal-to-noise ratio and to get the time delays of the Ps, PpPs, PsPs + PpSs phases within grids of 10 km × 10 km. Finally, the crustal thickness and Poisson’s ratio are calculated. The results show that the crustal thickness ranges from 28 to 40 km and the Poisson’s ratio ranges from 0.28 to 0.36. There exist two mantle-uplifting sites each with a horizontal scale of about 30 km × 30 km, one in Mazhan–Tengchong–Maanshan and the other in Wuhe–Longjiang–Tuantian. The high Poisson’s ratio is consistently located within these two sites. Recorded shocks with Ms > 2.0 reveal that most of the shocks are distributed around the two sites and few are located at the centers. The shocks, the geothermal distribution, and the crustal structure suggest that the magma is still active, and the two mantle-uplifting sites detected may be the positions of two magma chambers in the crust. |
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| Keywords: | Receiver functions Tengchong volcanic area Moho Poisson’s ratio Magma |
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