Mineral-magnetic signal of long-term climatic variation in Pleistocene fluvio-lacustrine sediments, Nihewan Basin (North China)

The Nihewan Basin (around 40 degrees N, North China) is a major focus of investigations into hominid occupation in the eastern Asia during the early Pleistocene, thus the paleoenvironmental evolution in this area is crucial for understanding of early human habitation at high northern latitudes of East Asia. To retrieve reliable long-term paleoenvironmental signals from the Nihewan fluvio-lacustrine sequences, I conduct an environmental magnetic investigation on the Pleistocene Xiantai fluvio-lacustrine sequence at the eastern margin of the Nihewan Basin. Results suggest that there exist an up-section decreasing trend in magnetic mineral concentration and grain size, which is attributed to a long-term decrease in abundance of magnetic minerals in the catchments and in transportation of detrital magnetic minerals into the Nihewan paleolake. I further reveal that these long-timescale variations are related to a long-term decrease in East Asian monsoon precipitation and humidity in the Nihewan Basin during the Pleistocene. This paleoclimate inference is consistent with the increasing aridification in Asian mainland during the Pleistocene, an important climate response to increasing global ice volume. (C) 2010 Elsevier Ltd. All rights reserved.