Abstract:
The Sichuan-Yunnan region lies in the southeast margin of the Qinghai-Tibet Plateau. It is the NS collisional-extruding front zone of the Indian-Eurasian continent, as well as the deep material escape zone of the Qinghai-Tibet Plateau. It is significant in revealing the dynamic process in the Qinghai-Tibet Plateau to study the characteristics of the gravity anomalies of the Sichuan-Yunnan region. Firstly, based on the latest high-precision World Gravity Map 2012 (WGM2012), we analyzed the spatial distribution anomalies of the free air gravity, Bouguer gravity and isostatic gravity in the Sichuan-Yunnan region. Secondly, the Bouguer gravity anomalies and isostatic gravity anomalies were decomposed by using the wavelet multi-scale analytical method, so as to analyzed the approximation and detail information characteristics and explored the relationship between gravity field and the inside tectonic activity of the earth crust. The results show that the gravity anomaly characteristics between the Sichuan Basin and the Songpan-Ganzi block on both the East and West sides of the Longmenshan fault zone demonstrate the existence of eastward material flow in the Qinghai-Tibet Plateau. The gravity anomalies in the Middle Yunnan Secondary Block confirm that, resisted by the rigid Sichuan Basin, the crustal flow from the Qinghai-Tibet Plateau moves northeastward along the Longmenshan fault zone on one side, and moves southward along the Xiaojiang fault, Honghe fault, and Lancangjiang fault on the other.