QUERY TO THE YUMUSHAN UPLIFT ON THE NORTH MARGIN OF QILIAN MOUNTAIN
PAN Hong_xun, GE Xiao_hong, LIU Jun_lai (Changchun University of Science and Technology, Changchun 130026, China)
Yumushan block on the north margin of Qilian mountain, with Jiudong basin and Minle basin to the west and east respectively, belongs to the fore-land depression in NNW direction at the north margin of the Qilian mountain fold belt. The Yumushan block has been thought of as a fault-uplift, which separates the two basins formed during late Yanshanian orogeny. However, the recognition of fault zones at the western margin of the Yumushan block, and the tectonic and sedimentary analyses of the Yumushan block and the basins, cast doubts to the tectonic property of the block. It is suggested that the two basins be derived from an united large basin at least during Mesozoic and the Yumushan block be nappe sheet formed due to NE imbricate thrusting on the north margin fault zone of the Qilian mountain. This proposal would provide valuable clues to further exploration of oil-gas and water resources in Hexi corridor basin belt.