Geometry and timing of Mesozoic deformation in the western part of the Xuefeng Tectonic Belt, South China: Implications for intra-continental deformation

The Xuefeng Tectonic Belt is an important intraplate structural system in the South China Block. Its west margin is up to 1300 km away the present-day continental margin, and the Mesozoic structural trends in this belt are perpendicular to and have no correlation with the Triassic Qinling-Dabie Orogenic Belt. This belt provides important clues for understanding the mechanism of intraplate deformation and the tectonic history of South China. We identified two generations of folding with different strike directions in the Xuefeng Tectonic Belt based on the youngest folding-involved strata and their overprinting relationship. The early one is NE-striking, overprinted by the N-S-striking folds both during Late Jurassic and Late Cretaceous. Thrust faults in the Xuefeng Tectonic Belt mainly show top-to-west thrust movement, which is approximately coeval with the N-S-striking folding. The thrust fault system can be divided into three zones: the root zone with steep thrusts, the middle zone characterized by imbricate thrusts, and the frontal zone with a few shallow thrusts. In addition, two generations of strike-slip faults with different structural trends have been identified: E-W-striking strike-slip faults showing dextral transpression, and NE-striking strike-slip faults with sinistral offset and controlling the upper Cretaceous basins. According to regional geological relationship and structural overprinting, we interpret that the E-W trending strike-slip faults formed in the first stage, whereas the NE-striking strike-slip faults formed later during an E-W-oriented compressional event. Therefore, the principal stress direction varies from NW-SE to E-W. (C) 2011 Elsevier Ltd. All rights reserved.