Fast slip-rate along the northern end of the Karakorum fault system, western Tibet

Abstract

The exact location of the northern Karakorum fault (KF) in western Tibet is unclear and its current activity is debated. Here, we investigate the possible northern extension of the KF, the Muji fault, located in the Chinese Pamir, which belongs to the Kongur Shan extensional system, and provide the first quantitative estimate of its Holocene slip-rate. The fault cuts and offsets a series of 6 fluvial terraces, yielding a minimum slip-rate of 4.5 ± 0.2 mm/yr, by matching the largest terrace riser offset with its upper surface age ( 10 Be, n = 24). Field evidences of right-lateral movement along the Kongur Shan fault, as well as geometry and kinematic similarities with the southern half of the KF attest that the Muji fault belongs to the KF system. Therefore, its fast slip-rate combined with the slow slip-rates along minor splays of the northern KF (maybe up to 4 mm/yr) southwest of the Tashkorgan basin agrees with the late Pleistocene southern KF slip-rate (>8 mm/yr). © 2011 by the American Geophysical Union.