Modern Movement And Deformation In The South China Sea Shown By GPS Measurements And Numerical Simulation

The South China Sea is located among the Pacific, Eurasian and Indio-AustralianPlates and is considered as an ideal natural laboratory for tectonic studies. Studyingthe movement and deformation of the SCS can enrich the dynamics theory ofmarginal seas, forecast the blocks' motion and provide basic suggestions for theexploiting and protection of the nature resources of the SCS. The purpose of thisdissertation is using the GPS data and numerical simulation to study the tectonicmotion of the SCS. The main conclusions are as follows:1) The geodetic results based on GPS data shown that the average extensionalrates was9.3mm/a in the S-N direction in the eastern SCS; the compressive rates weregreater than extensional rates which were weak in NW-SE direction in the westernSCS. The direction of extension is from the center basin to the south and north in theeastern SCS and from north to south in the western SCS.2) Using finite element method, several conclusions are as follows: A) theexistence of the strike-slip fracture in the western SCS leades to the expansion in thesouthern direction; B) the expansion of western Luzon islands existes; C) the jointmotion of Philippine Sea plate and Pacific plate makes the South China blockcircumrotated in the anticlockwise direction and the spreading from north to south inthe western SCS; D) the Philippine Fault may cause the Mid-Oceanic Ridge of theSCS to bend and move to the north; E) the mantle material upwelling leades themovement in the NW direction on Luzon Islands and the shift in the northerndirection of spreading axes in the SCS.3) We think that the movement of the SCS is an integrated result made byinteractions among different plates and the magma intrusion. Mordern movement of the SCS are the continuation of expansion at the beginning of Mesozoic. The reasonsfor decreasing of the expansion rate are the weakening of mantle flow upwelling andthe pushing by the eastern India plate and Myanmar block in the NE direction to theIndochina.