晚更新世黄土堆积物中的10Be记录

给出西峰黄土剖面0.15Ma以来¹⁰Be浓度、CaCO₃含量、粒度分布和有机质含量曲线。通过与深海沉积物δ¹⁸O曲线拟合,建立了西峰黄土剖面¹⁰Be时标,并与洛川黄土剖面¹⁰Be记录进行了对比研究。进一步计算了黄土堆积速率及¹⁰Be沉降量。

(10)Be RECORD IN THE LATE PLEISTOCENE LOESS DEPOSITS

Cosmogenic radioisotope ¹⁰Be as a tracer provides useful information regarding transport processes which are related to the formation of loess, The ¹⁰Be concentration measured in loess sample consists of a local component and a dust component. The upper 16.5m of Xifeng profile covering the last ca. 150,000a were sampled with a sampling interval of 20 cm corresponding to 2,000a. ¹⁰Be concentrations in loess samples were measured with AMS and is given together with the organic material and CaCO₃ concentrations as well as the abundance of different grain sizes. In order to establish a time scale of the Xifeng profile the ¹⁰Be record and the δ¹⁸O record of deep sea core V19-30 which the time scale was constructed more detail were synchronized by "wiggle matching". The agreement between the two curves is astonishingly good. This strongly supports our hypothesis that ¹⁰Be in loess primarily reflects climatic variations. Using the ¹⁰Be time scale of the Xifeng profile, loess accumulation rates and ¹⁰Be fallouts were calculated since the last glacial period. The ¹⁰Be records of two loess profiles in Xifeng and Luochuan are compared directly by matching the boundaries corresponding among the different lithological layers of them. Obviously, all ¹⁰Be points of the Luochuan profile are higher than that of the Xifeng profile. We can attribute this to the higher probability of attaching ¹⁰Be in fine grains.