Features of crust and lithosphere velocity structures along the north-south tectonic belt and adjacent regions in China

We conduct gravity data inversion using the Parker-Oldenburg method to calculate crustal thickness, and employ seismic tomography to research the three-dimensional velocity structure of the crust and mantle along the north-south tectonic zone in central China. According to results of calculation we attempt to reveal the crust and lithosphere structures and the deformation characteristics in the study area. Then we further discuss the deep causes of crust-mantle tectonic evolution in the Tibetan Plateau active zones, the upper mantle rheological property in the study area and its dynamics significance. Studies show that crustal thickness of the north-south tectonic belt is highly variable, with thickening crust in west, stable crust of Ordos Basin and Sichuan Basin in east, and thinning crust farther east. The boundary between thinning and thickening lithosphere is along the Da Hinggan Ling Mountains-Taihang Mountains-Qinling Mountains-Daba Mountains-Wuling Mountains. It is also the deep tectonic between the eastern continental margin zone and central Yangzi-Ordos Craton regions. Not only are the shallow geological structures different on both sides, but alos the physical properties and thermal activity in deep upper mantle are distinctly different. It indicates that, in the study area, the structure of lithosphere and asthenosphere and the distribution of deep material have lateral heterogeneity. The deep tectonic boundary between central regions and the Tibetan Plateau is roughly along 100-102 degrees E.