安徽宣城风成沉积—红土系列剖面ESR年代学研究

ESR DATING OF EOLIAN SEDIMENT AND RED EARTH SERIES FROM XUANCHENG PROFILE IN ANHUI PROVINCE

摘要:

本文利用电子自旋共振测年法(ESR)测定了安徽省宣城风成沉积-红土系列剖面的形成年龄。根据各层的年龄,可以将本剖面划分为三个形成期次:(1)早更新世晚期,形成年龄约为1000-730ka之间,包括砾石层和上伏的粉砂层;(2)中更新世早期,包括网纹红土及与其互层的棕黄色风成堆积层,其形成年龄在730-400ka之间;(3)中更新世晚期,均质红土(含夹于其间的棕黄色风成堆积层)属于本期,形成年龄约在400-100ka之间。年龄的精确测定,使我们有可能进一步研究“过去全球变化”,并为分析和提取剖面中贮藏的气候环境变迁的信息打下基础。

Abstract:

To elucidate the chronological characteristics of the Xuancheng profile in Anhui Province,the ESR ages of 10 samples were determined.The results indicated that the ESR age increased with the increase of stratum depth and followed the stratigraphic sequence.If taking the Brunhes-Matuyama boundary (B/M) (730ka) between early and middle Pleistocene,based on previcus researches and our ESR dating results,the gravel layer and the upper silt layer could be assigned to the later stage of early Pleistocene epoch(1000-730ka),Plinthitic red earth layers and-brown-yellow eolian sediment layers (from the 15th layer to the 6th) to the early stage of middle Pleistocene epoch (730-400ka),and the isotropic red earth (from the 5th layer to the 3rd) to the later stage of middle Pleistocene epoch (400-100ka).