汉江上游郧县段全新世特大洪水事件光释光测年研究

通过对汉江上游的野外考察，在湖北郧县段河谷发现了含有典型的古洪水滞流沉积物的全新世风成黄土土壤剖面。对该剖面采集样品，进行了沉积学分析，并且应用光释光技术中的单片再生剂量法（SAR）测定获得其OSL年龄，结合地层对比和文化层考古学断代，确定由古洪水滞流沉积层记录的特大洪水事件发生在距今1 800～1 700 a之间，对应于我国历史上的东汉至魏晋时期（A.D. 200～300）。通过与汉江上游地区、国内和世界各地的多种指标气候变化记录的对比分析，揭示出特大洪水事件发生在东汉至南北朝时期的气候恶化期。由于气候状态不稳定，降水变率大，致使严重地干旱和特大洪水皆有发生。该成果对我们深刻理解区域水文系统对于全球变化的响应规律具有重要意义

OSL DATING OF THE PALAEOFLOOD EVENTS IN THE YUNXIAN REACH OF THE UPPER HANJIANG RIVER

Field investigations were carried along the upper reaches of the Hanjiang River.Typical Holocence eolian loess soil profile with interbedded palaeoflood slackwater deposits (SWD) was found at the Liaowadian site at the Hanjiang riverbank in Yunxian county,Hubei province.A set of samples for sedimentary analysis and for OSL dating was taken from the profile.OSL age of the samples was obtained by using the single aliquot regenerative dose（SAR）protocol.In combination with the stratigraphic correlation and archaeological dating,the extraordinary palaeoflood events recorded by SWD were dated to 1800-1700 years during the Eastern Han dynasty and Weijin period (A.D. 200-300).The climatic records from the upper Hanjiang River basin and various regions within China and over the world indicated that the flooding episode corresponded to the global climatic decline that lasted for several centuries.The extraordinary floods occurred because of the climatic instability,that resulted in high variability of precipitation and resulted in great floods and droughts.This is of great significance in understanding the regional hydrological response to global climatic change