THE SERTENGSHAN ROCK GROUP IN MIDDLE-WEST INNER MONGOLIA: Revision and its geological significance

Based on the 1:50000 regional geological survey, the Sertengshan rock group is revised, involving the schist and marble of low-amphibolite to high-greenschist facies, which are distributed in middle and west Inner Mongolia. The rock group is characterized by a general order but internal disorder because of intense ductile shearing deformation. The Sertengshan rock group can be divided into four rock formations, i. e. from bottom to top, Dongwufenzi, Liushugou, Beizhaogou and Dianlisutai formation, covered by Meso-Neoproterozoic strata with unconformity at the top. Isotopic data proved that the forming age of the Sertengshan group is Neoarchean. The Dongwufenzi formation is an important Fe-bearing stratum, while the Liushugou formation is a significant stratum for Au deposits in Middle Inner Mongolia. The revision of Sertengshan rock group is significant for the study of Neoarchean tectonic evolvement in the northwestern margin of North China Plate and exploration for iron and gold deposits in the area.