Holocene environmental changes in the central Inner Mongolia, based on single-aliquot-quartz optical dating and multi-proxy study of dune sands

Alternating units of dune sands and paleosols in the central Inner Mongolia imply multiple episodes of dune building and stabilization, in response to the waxing and waning of the East Asian monsoon. Such eolian deposits were dated by using the single-aliquot-quartz optical dating method. Combined with the multi-proxy study on the deposits, the past environmental changes during the Holocene have been reconstructed. Our results indicate that widespread eolian sand mobilization occurred in the studied region during the beginning of the early Holocene from 11.5 ka to ∼ 9 ka. The climate became warm and humid during the period between ∼ 9 ka and ∼ 5.6 ka (Holocene Optimum). After ∼ 5.6 ka, the region again became arid, as inferred from dune building. However, the environmental changes during the late Holocene have been affected by both climate and human impacts, and the presence of desert environment in such semiarid region is not only the result of climatic drought of the late Holocene, but also related to poor land-use practices.