mm yr

seismic anisotropy

lower crust

stress field

tarim basin

upper mantle

fault zone

Journal of Geodynamics

• A deep fault cutting through the Moho surface is identified in the Xuefengshan belt. • Collisional belt of the Yangtze and Cathaysia Blocks is revealed based on identification of geophysical relicts. • Boundary between the Yangtze and Cathaysia Blocks is deduced based on the crustal structure. • Two groups of layered narrow slip belts in the middle crust of the Yangtz and Cathaysia Blocks are identified. • A narrow velocity gradient belt at a depth of ∼90 km in the upper mantle lithosphere is distinguished. In this study, we analyse and interpret a new seismic reflection profile across the Xuefengshan Belt (XFSB), South China, to determine the deep structure of this belt and provide insights into collisional orogenic architecture. We identify a deep regional fault located beneath the XFSB, which cuts through the reflection Moho below the belt and is interpreted as representing the collisional boundary between the Yangtze and Cathaysia blocks along the southeastern margin of the belt. We identify structural evidence for collision between the two blocks, including two groups of layered narrow slip belts (∼30 km) in the middle crust, one distributed in the Yangtze Block and the other in the Cathaysia Block. A narrow velocity-gradient belt in the upper mantle at a depth of ∼90 km is revealed by numerous strong seismic reflectors, some of which are layered. The study provides important new information on the lithospheric structure of the South China Block at the interface between the Yangtze and Cathaysia blocks.

Lithospheric structure of the xuefengshan belt, South China: Evidence from a seismic reflection profile