Late Pleistocene chronology of loess deposition near Luochuan, China

Abstract

AbstractLoess near Luochuan was sampled for thermoluminescence (TL) dating simultaneously with magnetic susceptibility measurements to provide the first independent age estimates on a susceptibility record from the Loess Plateau of China. TL age estimates on late Pleistocene loess (L1) are stratigraphically consistent with no statistical difference in TL ages by the total or partial bleach techniques or by measuring ultraviolet or green wavelengths in the TL analysis. Loess below the last interglacial soil (S1) yielded disparate results and is in many localities in central and eastern China unsuitable for TL dating because of complications of TL saturation and uncertainties in estimating the environmental radiation. TL age estimates on the L1 loess are consistent with previously reported TL ages for sites near Beijing and Xian as well as in general agreement with age models for loess deposition based on paleomagnetics and magnetic susceptibility. The convergence of a variety of geochronologic indices indicate that the last major period of loess deposition in central China began 70,000 ± 10,000 yr B.P. and terminated <20,000 yr B.P. This event is probably recorded in sediments from the adjacent Pacific Ocean and possibly in dust records from the Antarctic Ice Sheet.