QINGLING-DABA AULACOGEN

According to the recent studies on sedimentary, metamorphic, magmatic and volcanic formations, as well as the characteristics of later deformation stage in Qingling-Daba Area, it is believed that the aulacogen developed from Sinian to Triassic times with obvious polycycles and transversed zonation. The studied area experienced four stages of tension, faultdown, shortening and subsequent reformation. The authors of this paper suggest that the reformation also could take place during the period of formaion. As the small occeanic basins formed in Early Paleozoic within Shanxian-Erlangping region closed up by obduction, Qingling-Daba Aulacogen was shifted southward to Shanyang-Zhashui Area in late Caledonian Early Variscian. Thereafter, the aulacogen had continuously moved southward to Zhengan-Xunyang Area until the aulacogen itself ceased its aulacogenization. Qingling-Daba Area experienced the compression of horizontal Ew stress in late Indo-Chinese epoch while in late Yanshanian Himalayan, it was compressed by SN horizontal stress. The central belt of Shanxian-Erlang-ping thrusted to its both flanks in a large scale and finally the flower structures were formed.