Active Faulting in the Southern Bole Basin Within the Northern Tian Shan and Implications for Strong Earthquake Hazards and Tectonic Deformation, NW China

In compressional active orogenic belts, crustal deformation is accommodated by strike-slip faults and thrust faults. Studying the fault interactions of different types of active faults is important for understanding mountain building and seismogenic characteristics. This study uses field mapping, high-resolution digital elevation models, and in situ cosmogenic nuclides to present data from active thrusts and thrust-related folds on the southern margin of the Bole Basin, northern Tian Shan. These abandonment ages derived from in situ cosmogenic nuclides indicate that climate plays a significant role in controlling the alluvial surface incision. The crustal shortening rates of the eastern Jinghenan, central Jinghenan, and Yongji Faults are 0.21 +/- 0.04, 0.37 +/- 0.07, and 0.91 +/- 0.08 mm/yr, respectively. Based on the fresh fault scarps, three paleo-earthquakes are identified. The oldest paleo-earthquake (16.6 +/- 2.8 kyr) had a Mw of 6.5 +/- 0.3. The penultimate event (3.0 +/- 0.8-4.4 +/- 0.8 kyr) had a Mw of 6.6 +/- 0.3 or 6.8 +/- 0.3, while the most recent one (1.1 +/- 0.3 kyr) had a Mw of 7.0 +/- 0.3 or 6.5 +/- 0.3. Fault geometries and seismic activity indicate these thrusts and right-lateral strike-slip faults on both sides of Keguqin Range converge depth and form a positive half-flower structure. Crustal thickening outpaces denudation, showing that the Bole Basin is in an unsteady state. Keguqin Range is experiencing lateral growth, and as a result, the intermountain basins are expected to gradually diminish.