Layer-block tectonics of the Nansha microplate

Abstract: Based on an analysis of the data obtained from 50000 km of integrated geophysical profiles and relevant geological materials, layer-blocks of different orders have been distinguished within the Nansha microplate; they are the Nansha ultra-crustal layer-block, Zengmu crustal layer -block, Nanwei-Andu and Liyue-North Balawan crustal layer-block, Bisheng-Andu and Liyue-Banyue basement layer-block. The basic characteristics of these layer-blocks are discussed. The concept of "cross-deck bridge-like" movement of layer-block tectonics is proposed. In light of the view of the multi-geodynamic origin, the formation mechanism and main driving forces of these layer-blocks are probed. The subducted slab delaminating-mantle upwarping force, mantle flow drawing force, inertial force of earth rotation and regional plate boundary force are considered as the main forces driving the ultra-crust layer-block, and the gravity instability force and intracrustal rheological-plastic layer uplift force are considered as the forces driving the crust layer-blocks and basement layer-blocks.