The Toupo Fault, located in southern Anhui Province, strikes N60°～70°E in a linear route that is clear on satellitic image. It plays an important role in controlling the tectonics, geomorphology and distribution of Mesozoic-Cenozoic basins and strata. Detailed field investigation was carried out along the Toupo Fault to study its activity. Profiles, as well as a trench excavated reveal that the Quaternary super stratum above the fault had not been offset. The stratum was sampled and dated with TL methods to be the Mid-Pleistocene time, implying that the fault had been no longer active since then. Three stages can be divided since the fault was formed. The first stage is in the late Yanshan Movement, when the fault movement was of reversal strike-slipping and the tracks formed then are still clear today. The second stage is in the early Himalayan Movement—the late Cretaceous-early Tertiary, when the fault movement turned to be normal faulting and the southern wall became a tensile basin and received clastic sediment. The third stage is since the late Tertiary, when the tectonic movement was very weak. No late Tertiary sediments were formed and the Quaternary sediment was only as thick as ten meters. The geomorphology also suggested an aging form. Neither vertical nor horizontal displacement was evident along the Toupo Fault during this stage, though fault gouge dating suggested that the Toupo Fault might have been active during the Mid-Pleistocene.
Chen Wenbin Li Xiaojun Song Yisheng Pan Hua Huan Wenlin Xu Guangyin Jiang Hui You Huichuan
