Holocene geomorphic processes and landscape evolution in the lower reaches of the Orkhon River (northern Mongolia)

Abstract Geomorphological and sedimentological investigations in the lower reaches of the Orkhon River in northern Mongolia provide evidence for Late Pleistocene terraces, Holocene soil development, aeolian accumulation, soil erosion and slope wash. Optically stimulated luminescence (OSL) and radiocarbon dating of aeolian and colluvial sediments including paleosols show different sedimentation and soil formation periods. Luminescence data of 12.3 ka and 11.0 ka were obtained for basal sand deposits overlying slope bedrock and the Pleistocene terraces of the Orkhon River. OSL and radiocarbon data from aeolian sediments and paleosols indicated soil formation at around 11–10 ka, 7–6 ka and 3 ka. These periods can be associated with more humidity found in other areas of Central Asia as well.