THE FEATURES AND SEDIMENTARY ENVIRONWENTAL ANALYSIS OF THE CRETACEOUS STRATA ON THE NORTHEAST MARGIN OF HEFEI BASIN
Wu Yuedong; Hou Minjin; Liu Jiayun (Anhui Academy of Geological Survey, Hefei 230001 )
Cretaceous strata are developed broadly on the northeast margin of Hefei basin with complete sequence upward as early Cretaceous Xizhuang Formation and late Cretaceous Qiuzhuang Formation and Zhangqiao Formation. The measurement of stratigraphical profiles and 1:50000 scale regional survey mapping show that the Cretaceous sediments are all of terrestrial facies with great change in both vertical and horizontal directions where pluvial fan, alluvial fan, stream, eolian, shallow and deep lake facies occur. The formation and evolution of the northeast margin of Hefei basin is controlled by the Tan-Lu Fault. In the beginning of early Cretaceous, the left - handed strike - slip faulting caused northeast pulling -apart and formed rift and down - warped basin. and the NW - NE - trending extension of the fault resulted in graben - type rift basin by the late period of early Cretaceous.