Tectonic Characteristics of the Tibetan Plateau Based on EIGEN-6C2 Gravity Field Model

Gravity anomaly data are the results of gravity force field by all underground sources, including information in the shallow and deep parts of the earth. The studies of satellite gravity field have been increased in recent years, which provide important information for the study of deep structures under the Tibetan Plateau. Using EIGEN-6C2 gravity field data, we first analyze the Bouguer gravity anomaly and isostatic gravity anomaly from one to five scale decomposition based on multi-resolution analysis method. Then distribution characteristics of gravity anomaly sources in different depths are evaluated with the help of other geophysical factors, in order to recover the geometric characteristics in different scale. Second, we estimate the approximate depths of the geologic bodies using the power spectral analysis on the decomposed anomalies from first to fifth order. Third, the edge detection method based on Canny operator is employed to identify the undistinguished fractures, to further determine the block boundary in the Tibetan plateau and to divide blocks and sub-blocks that are active tectonically. Final, after sedimentary and lithosphere corrections, the three dimensional Parker-Oldenbarg inverse theory on the Bouguer anomaly is applied to invert Moho depths in Tibetan plateau.