Abstract: Seismic data show that the crust of the buried Bachu uplift in the central Tarim consists of the crystalline basement and Paleozoic strata, without Mesozoic and Cenozoic strata, and is unconformly covered by Quaternary terrestrial clastic rock. Both north and south margins of the Bachu uplift present intense deformation with basement-involved structures and thrust fault under the Paleozoic cover. A large-scale northward arcuate structure of the Tumuxiuke basement-involved fault is developed in the north margin of the Bachu uplift. By use of the fault-related theories, we interpreted 2D seismic data with the strata determined by the well logging data, and concluded that the Tumuxiuke basement-involved fault was formed by reactivation of the pre-existing basement-involved wedge-shaped structures. The Late Cenozoic India-Asia collision caused intense intracontinental deformations in the Central Asia and the reactivation of the Bachu uplift. It is unlikely that the pre-existing structures are perfectly perpendicular to the applied contraction direction of the new tectonic event,and most of these structures should consequently experience a strike-slip motion during the reactivation and the arcuate Tumuxiuke basement-involved fault was deformed by the progressive bending of once-straight structural trends (the pre-existing Tumuxiuke basement-involved wedged-shaped structure) during this time. The seismic data show that a wedge-shaped basement-involved structure is clear in the east part, but unclear in the west and central parts of the arcuate Tumuxiuke thrust belt, where many normal faults were formed in anticline core or fore-limbs of monoclines in the seismic reflection sequences. On the top and west parts of the orocline, the late basement-involved faults were developed on the pre-existing Tumuxiuke basement-involved wedge-shaped structures. On the east part of the orocline, the late Tumuxiuke basement-involved wedge-shaped structure reactivated the pre-existing wedge-shaped one. Our interpretations state clearly that there were three general strain zones and corresponding structures in the caprock monoclines that formed the above oblique-slip Tumuxiuke basement-involved fault in the western part of the arc-shaped structure, which is very similar to the physical modeling by Keating et al. (2012), but only in the two strain zones (extension and contraction) on the top of the arc-shaped structure. The extension faults are dominant in the upper-hinge region, while the contraction faults are dominant in the lower-hinge region, and the strike-slip faults are dominant in the middle of the fold limb. The boundaries of these three zones and the magnitude of strain in each zone vary with the oblique slip determined by its position in the arcuate structure.

Key words: Tarim basin, Bachu uplift, basement-involved, actuate structure, oblique-slip, normal fault