Late Pleistocene to Holocene slip rates for the Gurvan Bulag thrust fault (Gobi-Altay, Mongolia) estimated with 10Be dates -: art. no. 2162

[1] We surveyed morphotectonic markers along the central part of the Gurvan Bulag thrust, a fault that ruptured with the Bogd fault during the Gobi-Altay earthquake (1957, M 8.3), to document climatic and tectonic processes along the fault for the late Pleistocene-Holocene period. The markers were dated using Be-10 produced in situ. Two major periods of alluviation ended at 131 +/- 20 and 16 +/- 4.8 ka. These appear to be contemporaneous with global climatic changes at the terminations of marine isotope stages (MIS) 6 and 2. The vertical slip rates, determined from offset measurements and surfaces ages, are 0.14 +/- 0.03 mm/yr over the late Pleistocene-Holocene and between 0.44 +/- 0.11 and 1.05 +/- 0.25 mm/yr since the end of the late Pleistocene. The higher of these slip rates for the last similar to16 kyr is consistent with paleoseismic investigations along the fault [Prentice et al., 2002], and suggests that, at the end of late Pleistocene, the fault evolved from quiescence to having recurrence intervals of 4.0 +/- 1.2 kyr for surface ruptures with similar to4 m vertical offset (similar to that of 1957). The inferred recurrence interval is comparable to that of the Bogd fault (3.7 +/- 1.3 kyr) suggesting that the two faults may have ruptured together also earlier during the last similar to16 kyr.