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TECTONIC EVOLUTION OF HEFEI BASIN, NORTHERN DABIE MOUNTAIN IN THE MESOZOIC AND THE CENOZOIC

XUE Ai-min1;2, JIN Wei-jun1;2, YUAN Xue-cheng2   

  1. 1. Institute of Geophysics, Chinese Academic Science, 100101, Beijing; 2. Chinese Academy Geoexploration, 100083, Beijing
  • Received:1999-06-20 Revised:1999-06-20 Online:1999-06-20 Published:1999-06-20

Abstract: Analysis of sedimentation and erosion of the Hefei basin has demonstrated that the basin experienced multi-stage depression and uplifting in the Mesozoic and Cenozoic Era. The Jurassic stratum was distributed in the whole basin, however, the Middle to Late Jurassic stratum experienced extensive erosion. The main erosion area is located in the middle and wastern parts, the trend of erosion contours is of a SN direction The Cretaceous sedimentation was limited with in the eastern part of the basin and the main erosion area is located at the east-southern part. The sediments of the Eogene were distributed in the faulted basins controlled by the Dingyuan, Hanbaidu and Tanlu faults. The erosion centers were located in the eastern and southern parts. The erosion centers changed with time, and were controlled by the tectonic framework. According to the SN balance section, the basin compressed in the SN direction at the Early Jurassic, then relaxed and extended to form the EW faults at the Late Jurassic. The basin compressed in the EW direction during the Cretaceous, then extended in the SN direction at the Eogene. The EW balance section suggests that there are a great uplift ridge crossing the Shushan fault and Feizhong faults from Fanghushan in the south to Shoxian in the north. The great uplift formed in the Early Cretaceous, and existed until the Late Cretaceous. The Hefei basin was the back-arc foreland basin resulted from Dabie orogen compression. It experienced the compression thrust during the Early Jurassic, and the relaxation during the Jurassic to the Cretaceous. During the Jurassic, there was a wide sedimentation. The sedimentary center migrated from south to north During the Cretaceous the west and center part of the basin was uplifted, while the east part was a depression area. The sedimentary center was near the Tanlu fault During the Late Cretaceous to the Neogene, the basin was extended along the SN direction and the faulted basin was formed .