THE ESTABLISHMENT OF THE HAIGOU COMPLEX IN THE HAIGOU AREA OF ANTU COUNTY, YANBIAN, EASTERN JILIN, AND ITS GEOLOGICAL SIGNIFICANCE

The Haigou Complex, in the Haigou area of Antu County in Yanbian of eastern Jilin Province, was an informal lithostratigraphic unit established by the authors and their colleagues during the regional geological mapping of the Chaoyangtun area. The unit consists of three lithological units: the Tuanjie Formation consisting of clastic rocks and marbles; the Dongfanghong Formation consisting of intermediate to felsic volcanics, volcaniclastics, and tuffaceous sandstones; the iron-rich Sichazi Formation consisting of biotite granulite, plagioclase-amphibolite, and magnetite quartzite. The three formations are in fault contact with each other. They were intruded by Proterozoic and early Paleozoic granites. There is no recognizable stratigraphic sequence within the three formations. They may represent a Middle Proterozoic tectonic slice along the eastern segment of the northern North China Plate. The establishment of the Haigou Complex would be of significance in the following respects: middle Proterozoic lithostratigraphic subdivision and correlation, the formation and evolution of rift-valleys and its relation to mineralization, and the assembly of the Rodinia Supercontinent in the Late Proterozoic.