Joint inversion of surface wave dispersion and receiver functions for crustal and uppermost mantle structure in Southeast Tibetan Plateau
ZHENG Chen;DING Zhi-Feng;SONG Xiao-Dong;Institute of Geophysics,China Earthquake Administration;Department of Geology,University of Illinois at Urbana-Champaign;Key Laboratory of Seismic Observation and Geophysical Imaging,China Earthquake Administration;School of Geodesy and Geomatics,Wuhan University;
The Southeast Tibetan is of great scientific value to the problems about the uplift,crustal thickening and escape of the Tibetan Plateau.Through the analysis of observational data recorded by the temporary seismic stations deployed in the study area,crustal thickness,sediment thickness and a high-resolution S wave velocity model of the crustal and upper mantle have been derived.The results demonstrate:(1)Regional crustal thickness varies strongly,the crustal thickness becomes thinner gradually from northwest to southeast.(2)The sediment thickness is consistent with the distribution of sedimentary basins in the research area.(3)Thereare two main NS-trending low-velocity zones(LVZs)observed in the mid-lower crust.One of the LVZs starts from Chuanxibei sub-block and goes across the Lijiang fault into Dianzhong subblock.The other one follows the trace of the Xiaojiang fault until about 24°N.These two LVZs are separated by the high velocity anomaly under Sichuan Basin and the inner zone of Emeishan Large Igneous Province in the middle crust.