Late Quaternary slip-rate along the central Bangong-Chaxikang segment of the Karakorum fault, western Tibet

Abstract

Insight into the spatial and temporal changes of slip-rate is essential to understand the kinematic role of large strike-slip faults in continental collision zones. Geodetic and geologic rates from present to several million years ago along the Karakorum fault range from 0 to 11 mm/yr. Here, we determine the first late Quaternary slip-rate at the southern end of the linear Bangong-Chaxikang segment of the Karakorum fault, using cumulative offsets (20–200 m) of fans and terraces at three sites, as well as 74 new 10 Be surface-exposure ages to constrain the age of these offset geomorphic markers. The rate is >3 mm/yr at sites Gun and Chaxikang, and it is >1.7–2.2 mm/yr at the Gar fan site. Together with rates obtained along the southernmost Menshi-Kailas segment, the Karakorum fault slip-rate seems to increase southeastward from south of Bangong Lake to Kailas (from >3 to >8 mm/yr). These Karakorum fault slip-rate data (>3–8 mm/yr), together with the total length of the fault (>1000 km) and its initiation age (>13–23 Ma), confirm that the Karakorum fault is the major fault accommodating dextral strike-slip motion NE of the western Himalayas. The dextral Karakorum fault in the south and the conjugate left-lateral Longmu Co–Altyn Tagh fault system in the north are thus the major strike-slip faults of western Tibet, which contribute to eastward extrusion of Tibet.