Evolution history of Cretaceous to Cenozoic structural tectonic field in the Huicheng Basin along the the Qinling tectonic belt

The elongated, nearly W-E trending Chenghui basin obliquely cuts the Qinling orogenic belt, forming the morphological boundary between the east and west Qinling Range. This basin is composed of two sedimentary sequences, namely the Donghe Group below and the Chengxian Group above, contacted by an unconformity. Based on the sedimentary sequence analysis, fault kinematic analysis and paleotectonic stress field inversion, we established a deformation history of this basin featured by two extensional phases for basin formation and three compressional stress fields for basin redeformation. The results show that the Donghe Group was formed in Early Cretaceous under local NWW-SEE extension resulting from the E-striking, left-lateral strike-slip motion on the Mianlve Fault. This strike-slip basin suffered from NW-SE compressions, which caused gentle folding of the Donghe Group. A latest Early Cretaceous mafic dyke dated to be 107 Ma was emplaced in this folded Donghe Group, which suggests that this compressional deformation event should predate 107 Ma. The Chengxian Group, mainly consisting of red-colored muddy conglonerates and coarse sandstone and mudstones, was deposited in an NWW-SEE extensional setting, and was controlled by the E-striking Fen-Tai fault. This sedimentary group has recorded two compressional stress events: NNW-SSE compression and NNE-SSW compression, both of which occurred respectively in latest Cretaceous and in late Paleogene. These two events resulted in the inversion of bains-bounding faults: the Feng-Tai fault and the Mianlve fault, but the interior of the Huicheng basin was only weakly deformed. © 2019, Science Press. All right reserved.