甘孜黄土细颗粒石英热转移光释光(TT-OSL)法测年可行性初探

A PRELIMINARY DISCUSSION ON FEASIBILITY USING THERMALLY TRANSFERRED OPTICALLY STIMULATED LUMINESCENCE(TT-OSL)METHOD TO DATE THE FINE-GRAIN QUARTZ EXTRACTED FROM GANZI LOESS

使用一种新的光释光测年法——热转移光释光(TT-OSL)法对甘孜县城附近的甘孜-A剖面上的黄土细颗粒石英进行实验测试,以探讨该方法用于其测年的可行性。实验测试结果表明,样品的天然回授OSL(ReOSL)信号强度随地层深度增加而增大,表现出明显的积累。利用"替换点"分析方式对TT-OSL法的检验表明该方法能够用于甘孜黄土的测年。采用简单多片法(SMAR)和TT-OSL法分别对3个样品进行等效剂量(D e)测试及年龄计算,结果显示TT-OSL法得到的D e值及年龄明显大于简单多片法,但TT-OSL法年龄与前人磁性地层研究中的期望年龄相差比较大。研究初步认为,TT-OSL法可以对甘孜黄土进行测年,但是结果的可靠性还需要有更多的可信独立年龄验证。

This paper attempts to date the loess from Ganzi area, Sichuan province, using a new method-TT-OSL protocol for OSL dating. A preliminary experimental study was conducted loess from the Ganzi-A section. Testing result showed that the naturally recuperated OSL signal intensity increases with depth of stratum, being obvious accumulation. A ＇ replacement plot＇ analysis was applied to test the reliability of the TT-OSL protocol and showed a nice result. The De values of 3 samples were measured by SMAR and TT-OSL protocols, respectively, and ages were calculated. The comparison between De.rrosL and De_SMAR show the former was greater than that of the latter, and comparison between the ages is as well. However the ages of TT-OSL method is less than the expected value from magnetostratigraphy. Based on the results, the TT-OSL method was applied to fine-grained quartz extracted from the Ganzi loess. But the reliability of results from TT-OSL dating needed to be tested and verified by more independent ages.