晚更新世云南蒋家沟流域泥石流发育的热释光证据

TL Evidence of Debris Flow Developments in the Late Pleistocene of Yunnan Jiangjia Valley Basin

由于泥石流沉积物记录的时间信息对当地历史时期的降水量和气候变化等具有重要的指示意义，先后有一系列的测年方法在泥石流沉积物测年中应用，在此基础上尝试利用热释光（11L）单片再生剂量法（SAR）对云南东川地区达朵古泥石流堆积台进行测年。得到该剖面上12个样品的等效剂量值，采用中子活化分析技术测定各样品U、Th、K含量，算得年剂量率，获得达朵台地发育的时间范围为44．4～27．1kaBP。该台地在形成时期多次受到小江流水的改造作用，致使古今含水率差异较大、放射性元素u、n、K的含量随深度变化的相对标准偏差也较大（依次为17％、12％和11％），是年剂量率在同一台地内波动较大的重要原因，对年剂量率取算术平均值后所得到的修正年龄随深度变化的内部一致性较好。初步研究结果表明热释光单片再生剂量法在泥石流沉积物测年方面具有一定的潜力。

The debris flow sediments record the chronology in precipitation and climate change of local historical period has important implications. A serious of dating methods were applied to debris flow deposits chronology. Attempted to utilize thermoluminescence （TL） single aliquot regenerative dose （SAR） of ancient debris flow deposits dating at Daduo in Dongehuan, Yunnan Province, achieved the equivalent dose values of 12 samples of the section, measured U, Th, K content of each sample by neutron activation technique, calculated the annual dose, obtained the range of development time is 44.4 - 27.1 Ka BP. It indicated that the debris flow was still developed in the late Pleistocene ： the physical weathering of reeks in glacial was stronger which made minerals more broken and the precipitation in interglacial was more abuandant. The annual dose was ranther changeable which can be mainly attributed to the large scatter of water content between ancient and modern and the content of U, Th and K with depth. Standard deviation of U was 17% , Th was 12% and K was 11%. Ages of correc- tion which was divided by arithmetic average annual dose rate had good internal consistency. The preliminary research results show that the SAR protocol of TL is a potential dating method in obtaining the chronology of de- brris flow deposits.