横断山地区末次冰期冰碛物石英光释光测年的适应性

Applicability of OSL Dating the Quartz from the Tills of Last Glacial in the Hengduan Mountains

为了探讨青藏高原东部地区冰碛物光释光测年的可行性,在横断山脉北部竹庆盆地硬普沟3列侧碛垄上采集了7个样品,提取出38～63μm的石英,用单片再生剂量法(SAR)测量等效剂量(De),并对样品光释光信号的有关物理特性进行了研究.结果表明:SAR程序的循环比在可接受范围之内,热转移信号的贡献<4.2%,不会对研究样品的等效剂量测定产生明显影响.剂量恢复实验表明SAR程序能恢复实验室的已知剂量,说明SAR程序适于所研究样品的等效剂量测定.每个样品的等效剂量都大致呈对称分布,表明样品在埋藏前晒退良好.光释光年代结果(15～60ka BP)显示了较好的内部一致性,并且与地貌关系相符,整体上也与前人的研究结果相一致.

In order to investigate the applicability of dating tills from the Tibetan Plateau,seven samples were collected from three lateral moraines in Yingpu Valley of Zhuqing Basin in the northern Hengduan Mountains.Quartz grains of 38~63 μm were isolated and then the single aliquot regenerative-dose（SAR）protocol was employed for equivalent dose（De）determination.For all the samples,the recycling ratio is in the range of acceptability and the contribution of the thermal transfer signal is less than 4.2%;Dose recovery test shows that the laboratory dose could be recovered successfully.These indicating that the SAR protocol is appropriate for De determination.The nearly symmetrical De distributions in the probability density frequency plot indicate that quartz grains were well-bleached prior to burial.The OSL ages（15~60 ka）show good internal agreement and are concordant with geomorphologic observations.