Dip-slip rate determined by cosmogenic surface dating on a Holocene scarp of the Daju fault, Yunnan, China

The Daju and Lijiang-Daju fault zones which bound the Yulong Mountains on its northern and eastern perimeters, respectively, are segments of a continuous fault system that bends at Daju. Uplift of the Yulong Mountains, the southernmost glacierized mountain range in Eurasia, resulted from the normal faulting characteristics of the fault system. Using cosmogenic surface exposure dating with 10Be and 26Al, we have measured bedrock exposure ages as a function of elevation along an exposed bedrock scarp of the Daju fault. 10Be and 26Al exposure ages increase monotonically with elevation ranging from 2.6 to 9.6 ka over the 51 m scarp length giving an average dip-slip rate of 7.5 m/ka during the Holocene period and a vertical uplift rate of 5.7 m/ka. The 5.7 m/ka Holocene uplift rate and supporting geomorphic features suggest that the uplift of the Yulong Mountains mainly occurred in the Quaternary. The fast slip rate and seismic quiescence for the recent 2.8 ka call attention to the possible recurrence of large magnitude earthquake events along the fault zone.

Research highlights►The Holocene dip-slip rate of Daju fault is 7.5 m/ka. ►The uplift of the Yulong Mountains mainly occurred in the Quaternary. ►A large magnitude earthquake along the Daju fault zone is imminent or crust deformation structure underneath has changed.