Dating faulted alluvial fans with cosmogenic 10Be in the Gurvan Bogd mountain range (Gobi-Altay, Mongolia):: climatic and tectonic implications

The Gurvan Bogd mountain range is a fault system characterized by strong earthquakes (M similar to 8) separated by long periods of quiescence. Further to the previous works in the area, our study provides new data concerning the tectonic and climatic processes in the Gobi-Altay. To quantify the slip rates along the faults, we dated offset alluvial fans analysing the in situ produced Be-10 along profiles at depth. The slip rates along the Bogd strike-slip fault and its associated thrust faults over the Upper Pleistocene-Holocene period are 0.95 +/- 0.29 mm yr(-1) and comprised between 0.12 +/- 0.02 and 0.13 +/- 0.02 mm yr(-1), respectively. The surfaces ages account for a cyclic formation of the fans over the past similar to 360 ka, in correlation with the terminations of the marine isotope stages 2, 6, 8 and 10.