甘孜黄土细颗粒石英光释光测年初步研究  

A preliminary discussion on measurements of SMAR equivalent dose of fine-grain quartz extracted from Ganzi loess

作　　者：张克旗[1] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081

出　　处：《核技术》2012年第12期916-922,共7页Nuclear Techniques

基　　金：中国地质科学院地质力学研究所基本科研业务费项目(DZLXJK201109和DZLXJK200806)和地调项目(1212010914041)资助

摘　　要：采用简单多测片再生（SMAR）法对川西高原甘孜黄土的甘孜一A剖面的部分样品进行初步光释光测年研究。使用细颗粒（4—11lam）石英进行测试。对样品09GZA03的SMAR法等效剂量（D。）的预热坪实验表明，在200℃-260℃预热温度范围内能获得一致的D。值，但剂量恢复实验表明，对小于240Gy的样品本文的测试流程和条件较有效，更高剂量会明显偏低。使用SMAR法对剖面上间距0.3m采集的9个连续样品的细颗粒石英进行了Dc测试并计算出相应的年龄，显示了很好的Dc值及年龄随埋深变大的特征，表明SMAR法可用于甘孜黄土的细颗粒石英OSL测年，但对于天然剂量大于240Gy的样品（相应OSL年龄～5．5万年），其测年结果可能会偏低。Background： The western Sichuan Plateau is located on the southeastern margin of the Qinghai-Tibet. The loess-paleosol sequence distributed widely on the western Sichuan Plateau is among the best continuous records of the Quaternary climate and environment on the margins of the plateau. The new method and technology of OSL dating were developed and applied to Chinese loess in recent years. But there were less application to be attempted to the loess from the western Sichuan Plateau. Purpose： This paper attempts to date the loess from Ganzi area, Sichuan province, using a new method for OSL dating. A preliminary experimental study was conducted loess from on the Garzi-A section. Methods： The fine-grain quartz extracted from 10 loess samples was measured by SMAR protocols for a preliminary study of OSL dating. Results： The identical De at thermal treat 200~C-260~C was showed in preheat plateau test using SMAR protocol for the sample 09GZA03. The dose recovery test in SMAR for the sample 09GZA03 showed a better recovery ratio when the artificial dose is lower than -240 Gy. An obvious underestimation appeared when the lab dose is greater than -240 Gy. Conclusions： Based on the results, the SMAR method was applied to fine-grained quartz extracted from 9 samples which sampled at 30 cm interval. Their Des and ages become large with deep. The results show that SMAR protocols are able to dating the ages of fine-grained quartz from Ganzi loess, but the measured ages can be underestimated when the natural dose is greater than 240 Gy （-55 ka in the loess）. Key words OSL dating, Ganzi loess, Fine-grain quartz, SMAR protocol

关 键 词：OSL测年 甘孜黄土 细颗粒石英 SMAR法 

分 类 号：P597.3[天文地球—地球化学] P574.1[天文地球—地质学]