ABSTRACT
The Tan-Lu strike-slip fault system in eastern China extends more than 2000km with a total sinistral offset about 300–100km for its central-southern part and northern part respectively and the main fault and branch faults compose a herringbone structure. The convergence of the North and South China Blocks in late Triassic produced a south-convex belt at the south edge of the Dabie massif in the Qinling-Dabie latitudinal structural system. The Tan-Lu sinistral strike-slip offset accommodated parts of the movement of the west Pacific Ocean plate, and occured mainly during the Yanshanian. The displacement on the main fault was absorbed by N-S shortening in shear zones, thrusts and folded zones of the adjacent areas, e.g., a group of NE-trending shear zones on its east side such as the Sihong-Xiangshui, Wulian-Rongcheng, Dunhua-Mishan and Yilan-Yitong faults. The palaeomagnetism data from Triassic-early Cretaceous strata on both sides of the Tan-Lu zone suggest that there was a 15°–25° anticlockwise rotation in its cast side before the Early Cretaceous and not a large sinistral offset between two sides of the Tan-Lu fault. This is concordant with the changing tendency of fold trends in South China Block, from south to north, fold axes turning from ENE via NE to NNE. Crust shortening increased northward from 18% through 38% to 70%. The offset of the Tan-Lu system in its western side was absorbed by shortening of a scries of south-convex arc-structures, e.g., the Luxi and the Dabie arcs; the former consists of a series of listric imbricate south-thrusting faults which were translated into detachment faults at a later time. The mechanism of the Tan-Lu faulting might be a segmental progressive northward migration. There are four stages of stress evolution in the Tan-Lu fault system: sinistral transpressional ductle shear (T3-J1•2); sinitral brittle transtensional shear (J3-K1); extension (K2-E); dextral transpressional and transtensional shear (N to now).
