Fast slip-rate along the northern Karakorum fault explains fast uplift of the Chinese Pamir

The exact location of the northern half of the Karakorum fault (KF), in the western Tibetan Plateau is unclear and its late Quaternary activity is debated. We provide the first quantitative estimate of the Holocene slip-rate along what we believe is the northernmost extremity of the right-lateral KF system (the Muji fault), located in the Chinese Pamir. The fault cuts and offsets a series of 6 fluvial terraces by 41 m at most. 10Be cosmogenic surface-exposure dating (n=24) of T6 and T4 surfaces around the larger offset yields average ages of 9 and 3.7 ka, respectively, therefore yielding a slip-rate at Muji ranging from minimum 4.5 to maximum 11.1 mm/yr. However, an intermediate, non-dated, terrace T5 allows to narrow down the range of slip-rate to a maximum of ~7 mm/yr, constrained from terrace riser heights. Fast slip along the northernmost segment of the KF indicates that 1) it is currently active, 2) combined with fast left-lateral movement along the Karakax fault to the east, might be the main factor contributing to the Chinese Pamir uplift.