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EVOLUTION OF JIYANG DEPRESSION AND ITS TECT0NIC IMPLICATIONS

Zong Guohong1, Xiao Huanqin1, Li Changbo11, Shi Yangshen2 Wang Liangshu2   

  1. 1.Institute of Geosciences, Shenli Petroleum Administration, Shandong, Dongying 257015; 2. Department of Earth Sciences, Nanjing University, Nanjing, 210093
  • Received:1999-09-20 Revised:1999-09-20 Online:1999-09-20 Published:1999-09-20

Abstract: The Meso-Cenozoic Jiyang depression is an assemblage of the negative inversion basin, dextral transtensional basin and active rift with four evolutionary phases. 1. The intraplate thrust orogenic phase (from the Triassic to Middle Jurassic): represented by the development of five NW-striking compressive belts, which were mainly reverse faults. 2. The negative inversion phase (from the Late Jurassic to Early Eocene, i.e., 149~45Ma): the negative inversion of the previous reverse faults, leading to the development of SN-striking high- dip normal faulting. Therefore, the sediments mainly deposited in the NW –trending half-grabens. 3. The dextral transtensional phase (from the Late Eocene to Oligocens, i.e., (45~24.6Ma): development of the NE-striking dextral transtensional faults, the WNW-trending sinistral transtensional fault, the secondary ENE-striking dextral transtensional fault and the EW- striking normal fault. These faults controlled the sedimentation in the basin and the previous faults became inactive. Consequently, the dextral transtensional basin overlapped the negative in version basin. 4. The active rifting phase (from the Miocene to Holecene, i.e., (24. 6Ma~present): the previous differential block faulting was replaced by the regional depression. The evolution of major faults in the Jiyang depression could be used to interpret the shearkinematics history of the Tan. Lu fault zone in the Meso-Cenozoic. The results of this study demonstrated that the Jiyang depression underwent dextral shear during the Triassic, sinistral shear from the Late Jurassic to the Early Eocene, dextral shear from the Middle Eocene to the Oligocene, an d weak dextral transpression from the Miocene to the Holocene.