新生代透长石SK01作为^(39)Ar-^(40)Ar法定年标准物质的均匀性检验  

Homogeneity Test of Cenozoic Sanidine SK01 as National Standard Reference Materials for ^(39)Ar-^(40)Ar Dating

作　　者：李洁[1,2] 陈文[1] 刘新宇[1] 张彦[1] 陈岳龙[2] 杨莉[1] 

机构地区：[1]大陆构造与动力学国家重点实验室,同位素热年代学实验室,中国地质科学院地质研究所,北京100037 [2]中国地质大学(北京),北京100083

出　　处：《岩矿测试》2013年第2期213-220,共8页Rock and Mineral Analysis

基　　金：科技基础性工作专项项目(2008FY130200);地质矿产调查评价项目(1212011120294,1212010816039)

摘　　要：39Ar-40Ar法定年分析过程中,对标准物质的需求有两个特点,一是需要将被测样品和年龄已知的标准样品同时放在核反应堆中进行快中子照射,标准样品的年龄直接参与被测样品年龄的计算;二是标准样品作为39Ar-40Ar法定年中的标尺,要求其年龄和被测样品年龄不宜相差太远,因此需要研制具有不同年龄值的标准物质用于分析不同时代地质样品。本文在研制新生代地质样品39Ar-40Ar定年标准物质过程中,通过综合研究,选定了可可西里风火山超浅成石英斑岩中的透长石SK01作为候选标准矿物,按照规定对其39Ar-40Ar年龄值(特性量值)进行均匀性检验。统计结果显示,特性量值的F值为0.857,小于F临界值2.08,相对标准偏差为0.66%,远小于规定的5%范围,证明本批样品的均匀性良好,符合国家一级标准物质技术规范(JJG 1006—94)要求。模拟运输过程进行颠震试验,试验结果 F值为0.00697,远小于F临界值6.59,其相对标准偏差为0.58%,远小于规定的5%范围,证明样品在运输过程中颠震对其均匀性无影响。最小取样量试验表明,在目前的实验条件水平下,为保证标准物质作为准确的年龄标尺的作用,透长石SK01的39Ar-40Ar年龄标准物质最小取样量为5 mg。综合检验结果表明,本批所选的新生代透长石SK01样品的均匀性良好,可以用于39Ar-40Ar年龄标准物质的定值分析。The 39Ar-40Ar dating technique yields high-precision results, and all age data depend on accurate ages of National Standard Reference Materials that are irradiated together with the unknown age samples. Reference material is not only essential for obtaining 39Ar-40Ar isotopic age, but also the main factor to affect the quality of the 39Ar-40Ar age data. In order to eventually obtain accurate 39Ar-40Ar age, it＇s is significant to develop reference materials with different age values. In this paper, Sanidine SK01 as the Cenozoic reference material of 39Ar-40Ar dating method was separated from hypabyssal quartz porphyI7 in the Fenghuo Mountain of Kekexili. Statistics of analytical data show that F value of 39Ar-40Ar of 0. 857 was less than its threshold F value of 2.08, and its RSD of 0.66% was less than the required 5%. The good homogeneity of SK01 met the requirements of the national first- grade technical specification for standard materials as JJG 1006--1994. Through simulating the transport process, 39Ar-40Ar age analytical data showed that F value of 0. 00697 was less than its threshold F value of 6.59, and its RSD of 0. 58% was less than the required 5% , which proved samples maintained a good homogeneity during transport. In order to ensure the quality of 39At-40 Ar dating, the minimum sample weight of 5 mg was recommended. The tests results indicated the homogeneity of Cenozoic sanidine SK01 is good, which satisfies the quantitative analysis of 39Ar-40Ar dating.

关 键 词：新生代透长石SK01 39Ar-40Ar同位素定年 标准物质 均匀性检验 

分 类 号：P619.235[天文地球—矿床学] TQ421.31[天文地球—地质学]