Kinematic features of Darlbute fault in northwestern margin of Junggar Basin
Fan Chun, Su Zhe, Zhou Li
1. Key Laboratory of Marine Evolution and Hydrocarbon Accumulation Mechanism, Ministry of Education, China University of Geosciences, Beijing 100083;
2. State Key Laboratory of Lithosphere Evolution, Institute of Geology and Geophysics, Chinese Academy of Science, Beijing 100029;
3. PetroChina Yumen Oilfield Company, Jiuquan, Gansu 735019
Darlbute fault is located on the northwestern boundary of the Junggar Basin and it is considered to be a typical large-scaled reverse fault. Field work and investigation indicates that, Darlbute fault is also characterized by a sub-component of sinistral stike-slip faulting. The maximum displacement is displayed in the Paleozoic formations along its southwestern segment, ～60 km offsets. Many meso-and micro-scaled brittle and ductile structures coextensive along the fault demonstrate that the Darlbute fault experiences multi-staged activities and the sinistral stike-slip faulting might prevaile from the earlier stage into the later. Besides, we also speculate that Lake Aibi, Heshituoluogai Basin emerged at the end of the Darlbute fault both are considered to be pull-apart basins; while, the dome in north-west part of the fault also acts as a transpression structure produced by the displacement motion of the Darlbute fault during activities. They accommodate most of the sinistral displacements. We speculate all of them compose a conjugated fault system together with the Altai fault system, that is, the NE-SW left-lateral strike-slip faults with a series of NW-SE dextral faults. The conjugate fault system in this region may indicate a consistent dynamic background regime of north-south extrusion towards the northern boundary of the Tibetan Plateau.