关键词: 顺北地区, 走滑断裂带, 分段性, 活动性, 形成机制

Abstract:

Strike-slip faults are widely developed in the Shunbei area, Tarim Basin, which play an important role in the hydrocarbon migration and accumulation. In this study, based on 3D seismic data interpretations of the western Shunbei area, the profile and plane geometry features, fault activity, active periods, and formation mechanism of the Shunbei-11 fault are characterized and analyzed. The Shunbei-11 fault extends to NNW for over 100 km, and is characterized by vertical/horizontal segmentation: The northern part is dominated by coeval transpression and transtension; two secondary faults formed a pull-apart graben in the middle part; a horsetail splay consists of several terminated branching faults in the southern part. The fault activities differ in deep and shallow layers, and decrease generally from south to north. The surface fault zone propagates from north to south, and the kinematic signatures suggest that it is a dextral strike-slip fault. Shunbei-11 fault underwent multiple active stages, and most of the fault has experienced two stages in the Late Ordovician (pre-T₇⁰) and Late Silurian-Middle Devonian (pre-T₆⁰), while some parts were active till Carboniferous. In terms of activity and kinematic features, the fault is similar to the NNW-trending strike-slip system of the Tabei uplift, but different from the NE-trending sinistral strike-slip system in the Tazhong uplift. Under the principal compressive stress (from north to south), and originated from the multistage collision of the South Tianshan Ocean north of the basin, the fault propagated from north to south, and the way of development and propagation was similar to that of the northern part of the Shunbei-5 fault.

Key words: Shunbei area, strike-slip fault, segmentation, fault activity, formation mechanism