MAJOR THRUST SHEET IN THE DAQING-SHAN MOUNTAINS, INNER-MONGOLIA, CHINA

Small thrust faults in the Daqing Shan that were previously mapped as separate structures belong to a single Mesozoic thrust, herein named t he Daqing Shan thrust. It extends more than 155 km along the northern margin of the Daqing Shan, obliquely cutting the Daqing Shan along the western flank of the Jinluandian peak to the southeast and taking its way to Chayouzhongqi to the east. Kinematic markers indicate tectonic transport oi the thrust sheet to the NNW. Minimum displacement, based on the observable outcrops, is 22 km, and the inferred thrusting dist ance may be larger than 35 km. The thrust sheet covers the whole easte rn area of the Daqing Shan. The thrust truncates the E-W trending, som ewhat older South-directed Panyanshan thrust and, therefore, the two f aults are not as a result of counter thrusting. Such major intraplate tectonic deformation that occurred in the Inner Mongolia Axis or the Y in Shan latitudinal tectonic belt during late Jurassic time calls for deep thought on its tectonic significance in dynamics. It is most like ly that the Daqing Shan thrust represents major intraplate shortening during Jurassic-Cretaceous closure of the Mongolo-Okhotsk ocean about 1000 km away to the north.