钾-氩和氩-氩定年样品的送样要求及预处理  

Submitting Terms and Pretreatment of K-Ar and Ar-Ar Dating Samples

作　　者：刘玉琳[1] 苗国均[1] 黄宝玲[1] 

机构地区：[1]北京大学造山带与地壳演化教育部重点实验室和地质学系,北京100871

出　　处：《岩矿测试》2003年第4期297-299,共3页Rock and Mineral Analysis

基　　金：国家重点基础研究发展规划课题(2001CB409807)

摘　　要：介绍了K Ar和Ar Ar法定年样品的送样要求及实验室预处理程序,样品粒度以250～180μm为宜;用量则视样品的K含量和年龄情况而定,K含量越高、年龄越老,所需样品量越少,多数样品的用量在几十至几百毫克;对于年龄情况不清楚的样品,10～20g手标本或者1～2g合适粒度的样品可以保证用量。全岩样品常受蚀变和捕虏晶的影响,有效的预处理可以在很大程度上消除这些干扰因素。文章还介绍了用稀HNO3消除碳酸盐、1.7mol/LHF消除轻微蚀变的影响以及电磁选剔除捕虏晶的实验过程。Submitting terms and pretreatment of KAr and ArAr dating samples are discussed in this paper.Particle size of 250～180 μm (60～80 mesh) is appropriate both for sample homogenization and the removal of atmospheric argon. The amount of sample used for dating is according to abundance of potassium in samples and the age of the samples. The higher abundance of potassium in samples and the older of the sample age, the less amount of the sample used. Several tens to several hundred micrograms of sample are needed for the most circumstances. For unknown samples, 1～2 grams of 250～180 μm or 10～20 grams of hand samples is enough. Whole rock samples are easily affected by alteration and xenocryst and effective sample pretreatment is important to get rid of these disturbances. This paper also introduces the procedures of eliminating the effects from carbonatization and other alteration using dilute nitric acid and 1.7mol/L hydrofluoric acid and the removal of xenocryst by electromagnetic separation.

关 键 词：钾-氩 氩-氩 样品 送样要求 预处理 粒度 酸侵蚀 磁分选 

分 类 号：P611.5[天文地球—矿床学] P597[天文地球—地质学]