TL evidence of debris flow developments in the late pleistocene of Yunnan Jiangjia valley basin

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 Dongchuan, 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 correction 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 debrris flow deposits. (authors)