A tectonic melange belt was discovered in the Sanligang Sanyang area, Hubeiprovince, along the west sector of Xiangfan-Guangji fault, east part of the south boundary of Qinling Orogenic Belt. It was composed of different tectonic blocks with varied lithological features and ages, mainly including ophiolitic blocks, island-arc volcanic blocks, pelagic sediments, fore-arc volcano-sedimentary system, and massives of the basement and covering strata of the Yangtze Block. These massives were emplaced in the west sector of Xiangfan-Guangji fault, which was a boundary between the Qinling Orogenic Belt and the Yangtze Block. Based on the detailed structure analysis of deformation of the Sanligang Sanyang tectonic melange belt, and compared with regional geology, it was suggested that the tectonic melange belt evolved four stages of deformation: 1) the high temperature ductile deformation in Middle Triassic, characterized by mafic mylonite which represented the high temperature ductile shear zone formed during the collisional event; 2) the middle temperature overthrust in Late Triassic and Early Jurassic, characterized by duplex in ophiolite, felsic mylonite in the south boundary fault and fold deformation of the foliation of mafic mylonite; 3) the right lateral shearing from Middle Jurassic to Early Cretaceous, featured by asymmetric folds with vertical hinge lines; and 4) the stretch-normal faulting in age of Late Cretaceous, bounded on the north side of the tectonic melange and controlled the formation of fault basin and Upper Crataceous depositing.
Dong Yunpeng,Zhang Guowei,Yao Anping et al. DEFORMATION AND EVOLUTION OF THE SANLIGANG-SANYANG TECTONIC MELANGE BELT ALONG THE WEST SECTOR OF XIANGFAN-GUANGJI FAULT[J]. Chinese Journal of Geology, 2003, (4): 425-436.