A tentative discussion on strike-slipping character and formation mechanism of western-edge fault belt in South China Sea

Abstract：The western-edge fault belt is the most dominating structure element in the west of South China Sea. It runs through the main sedimentary basins from north to south and has the property of strike-slip fault. The western-edge fault belt forms different arrangements of faults because of diverse strike-slipping directions at various geological times. Faults arrangements consist of negative flower structure, two groups en-echelon faults of northeast and northwest strike and double horse-tail shaped structure associations in plane. The main fault of the western-edge fault belt is of single stripe pattern and evident segmentation movement. Faults character of transform belts between north and south stepover zones is the compounding of negative flower structure, listric normal fault and dominoes reversing adjusting normal fault. According to an integrated analysis, the western-edge fault belt of South China Sea is considered as an long-active fault belt，and its strike-slip movement took place from middle Eocene to Quaternary. The movement of the western-edge fault belt was mainly right-lateral with extension-wrest stress, but during the end of middle Miocene, the direction of strike-slip movement changed to left lateral with extrusion-wrest stress, which resulted in regional strata uplift and erosion. Under these actions, the pattern of current sediment and structure was formed basically in the western basins of South China Sea.