现代环境研究室知识库

The objective of this study is to construct a numerically dated chronology of the last interglacial paleosol (Si) in Chinese loess using luminescence dating. The recuperated optically stimulated luminescence (ReOSL) dating approach was applied to 18 closely-spaced (20 cm intervals) samples, with 15 of these collected from the S(1) unit at the Weinan site, which is located at the southeastern margin of the Chinese Loess Plateau (CLP). By using the multiple-aliquot regenerative-dose (MAR) approach, 18 fine-grained quartz ReOSL equivalent dose (D(E)) values, spanning about 249-466 Gy, were obtained. The validity of ReOSL MAR protocol was checked by dose recovery measurements and recycling ratio tests. By comparison of the dose-response curves of all the samples, we found that it is feasible to construct a standardized growth curve (SGC) for the ReOSL signal at the Weinan site. Considering the effects of pedogenesis of the S(1) unit during formation, the dose rate during the last interglacial was corrected, which should be beneficial for constructing a more reliable chronology. Finally, a detailed chronology of the S(1) unit was established. The results show that S(1) was deposited between approximately 76-127 ka, which confirms the early suggestion that the S(1) unit in Chinese loess corresponds to the whole marine oxygen-isotope stage (MIS) 5. The detailed ReOSL chronology of S(1) indicates the consistency of the substrata of S(1) with MIS 5a-e, but cannot determine whether they are exactly coeval. According to the present ReOSL age results, it is suggested that dust deposition is continuous at timescales larger than 14.1 +/- 11.8 ky during the last interglacial and there is no hiatus longer than 4.4 +/- 13.0 ky at the L(2)/S(1) transition. Further work, e.g. minimizing the errors on ages and reducing the luminescence sampling intervals, is needed to understand the more detailed dust deposition conditions during the last interglacial in Chinese loess. (C) 2011 Elsevier B.V. All rights reserved.