New recognition of Gaxue Formation and Zedang Formation in Yalu Tsangpo Suture Zone
ZHANG Xinquan1, WANG Jingui1, ZHANG Zhenli2, ZHUAN Shaopeng1, ZHANG Liguo1, CHENG Zhou1, DENG Ke3, HE Jiaoyue1
1.Regional Geology Survey Institute of Hebei Province, Langfang 065000, China; 2.Hebei GEO University, Shijiazhuang 050031, China; 3.No.5 Geological Party, Tibet Bureau of Geology and Mining Exploration and Development, Golmud 816000, China
Abstract：On the basis of the 1:50 000 regional geological survey, the authors comprehensively studied Gaxue Formation and Zedang Formation in North Yalu Tsangpo Suture Zone, and compared their petrogeochemical parameters and tectonic environment with ophiolite. Combined with paleontological and high-precision isotope dating analysis, it is preliminarily considered that Gaxue Formation, Zedang Formation and ophiolite are products of different genetic types. Gaxue Formation and Zedang Formation were formed in the intra-oceanic arc tectonic environment from late Jurassic to early Cretaceous, and belonged to the front arc basalt (FAB type) which was the standard oceanic plate stratigraphic sequence. In the late subduction and collision process, the main body of Gaxue Formation and Zedang Formation was transformed into melange or existed in the melange belt in the form of a broken clip (block), mainly as the structure styles in subduction and accretionary complex zones. This understanding is of great geological tectonic significance for the rational restoration and establishment of the northern belt oceanic plate stratigraphic sequence of Yalu Tsangpo Suture Zone.
2020, Vol. 7 
