Structural and stratigraphical constraints on the kinematics history of the southern Tan-Lu fault zone during the mesozoic Anhui Province, China

摘要

The Tan-Lu Fault Zone (TLFZ) extends in a NNE-SSW direction for more than 2000 km in Eastern China. It has been considered either as a major sinistral shike-slip fault, as a suture zone or as a normal fault. We have conducted a structural analysis of the southern segment of this fault zone (STLFZ) in the Anhui Province. The ages (Triassic to Palaeocene) of the formations affected by the faults have been re-appraised taking into account recent stratigraphical studies to better constraint the ages of the successive stages of the kinematics of the STLFZ. Subsequently, the kinematics of the faults is presented in terms of strain/stress fields by inversion of the striated fault set data. Finally, the data are discussed in the light of the results obtained by previous workers. We propose the following history of the STLYZ kinematics during the Mesozoic. At the time of collision, a similar to NNE orientated Tan-Lu margin probably connected two margins located north of the Dabie and Sulu collision belts. During the Middle-Late Triassic, the SCB has been obliquely subducted below the NCB along this margin which has acted as a compressional transfer zone between the Dabie and Sulu continental subduction zones. The STLFZ has been initiated during the Early Jurassic and has acted as a sinistral transform fault during the Jurassic, following which the NCB/SCB collision stopped. A similar to NW-trending extension related to metamorphic domes was active during the basal Early Cretaceous (similar to 135-130 Ma); it has been followed by a NW-SE compression and a NE-SW tension during the middle-late Early Cretaceous (similar to 127 to similar to 105 Ma, possibly similar to 95 Ma); at that time the TLFZ was a sinistral transcurrent fault within the eastern part of the Asian continent. During the Late Cretaceous-Palaeocene, the STLFZ was a normal fault zone under a WNW-ESE tension. (c) 2007 Elsevier B.V. All rights reserved.