地震地质 ›› 2005, Vol. 27 ›› Issue (4): 586-598.

• 研究论文 • 上一篇    下一篇

西南天山明尧勒背斜河流阶地沉积物的光释光测年

王昌盛, 陈杰, 张克旗   

  1. 中国地震局地质研究所, 地震动力学国家重点实验室, 北京, 100029
  • 收稿日期:2005-12-11 修回日期:2005-12-15 出版日期:2005-12-08 发布日期:2009-10-26
  • 作者简介:王昌盛,男,1981年生,2003年毕业于防灾技术高等专科学校,现从事释光测年研究,电话:010-62009099,E-mail:wcs1999@163.com.
  • 基金资助:
    地震科学联合基金重点课题(201018);国家发展与改革委员会项目(20041138);国家自然科学基金(40372081)共同资助。

OPTICALLY STIMULATED LUMINESCENCE DATING OF FLUVIAL DEPOSITS FROM THE MINGYAOLE ANTICLINE IN THE SOUTHWESTERN TIAN SHAN

WANG Chang-sheng, CHEN Jie, ZHANG Ke-qi   

  1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China
  • Received:2005-12-11 Revised:2005-12-15 Online:2005-12-08 Published:2009-10-26

摘要: 晚第四纪细颗粒河流阶地沉积物的准确定年是当前光释光测年研究中的一个难点。利用简单多片再生法(SMAR)、单片再生法(SAR)等对新疆西南天山喀什前陆盆地明尧勒背斜喀浪勾律克河阶地沉积物样品的细颗粒石英光释光(BLSL)信号、混合矿物红外释光信号(IRSL)和红外后蓝光释光信号([Post-IR]OSL)进行测量。通过对比同一样品的细颗粒石英BLSL、混合矿物IRSL和[Post-IR]OSL的等效剂量值,认为细颗粒石英简单多片再生法是河流阶地沉积物释光测年最为适用的方法之一。对于细颗粒混合矿物而言,由于长石矿物的异常衰退,对于等效剂量De>70Gy的样品,其IRSL等效剂量值均偏小;其[Post-IR]OSL等效剂量值仍需慎重使用。通过对同一样品细颗粒石英多个测片的单片再生法等效剂量值分布以及简单多片再生法多个测片校正后天然释光信号强度的一致性判断,认为样品LEDL03-87q,LEDL03-86q和LEDL04-54q在沉积时的光晒退是不均匀的,采用最小等效剂量组分来计算沉积年龄。

关键词: 河流阶地沉积, 光释光(OSL)测年, 简单多片再生法, 单片再生法, 等效剂量, 细颗粒石英

Abstract: Optical dating of fine-grained fluvial sediments remains a complex endeavour. Five fluvial sediments have been collected from the Kalanggouluke He,Mingyaole anticline,in the Southwestern Tian Shan. We employ both ‘Double-SAR' and ‘Double-SMAR' procedure in which aliquots are subjected to both infrared (λ=860nm) and blue (λ=470nm) stimulation and two sets of De determinations are produced and assumed to relate predominantly to feldspathic and quartz fine grain populations respectively. There are significant differences between the equivalent doses for the IRSL and (post-IR) OSL measurements. We extracted fine-grained quartz via etching in fluorosilicic acid for sample LEDL03-87q,LEDL03-86q and LEDL04-54q. SMAR procedure (Wang et al.,2005) and SAR procedure were used to determine their equivalent dose (De). Our data indicate a significant IRSL De underestimate due to anomalous fading of the natural IRSL from feldspathic fine grains for all the samples. Caution should be taken when using the post-IR OSL De for fluvial sediments. BLSL De distribution analysis indicates that samples LEDL03-87q,LEDL03-86q and LEDL04-54q were partially bleached. We suggest using the minimum component of De to estimate their ages.

Key words: fluvial deposit, OSL dating, SMAR, SAR, equivalent dose, fine-grained quartz

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