187Re-187Os Calibration of Molybdenite from Henderson, Colorado: A New NIST Reference Material

0111876斯坦基于Re(Re)到Os(Os)衰变的地质计时仪的使用正在迅速扩大，目前还没有得到美国国家标准与技术研究所(NIST)认证的实验室间比较的标准物质。化学和质谱学方法的进步使Re和Os的高精度测定成为可能，即使在低ppt水平的样品上也是如此。辉钼矿(MoS_2)是唯一适合Re-Os计时仪的矿物，因为它通常含有高浓度的母体Re，基本上没有初始的子体O。因此，即使在非常年轻的样品中，187Re到187Os的衰变也会产生精确的年龄，而不会对初始的Os进行修正。随着对Re-Os测年需求的增加，尤其是辉钼矿的Re-Os测年，实验室间比对的标准物质的需求变得至关重要。我们建议与阿尔伯塔大学和NIST合作，校准一个Re-Os辉钼矿标准物质。拟议中的Re-Os参考辉钼矿来自科罗拉多州亨德森，那里是一个研究充分的钼矿床所在地。NIST将对亨德森辉钼矿粉末进行物理混合、分离和装瓶。科罗拉多州立大学的AIRIE实验室和艾伯塔大学的同位素实验室将对具有统计代表性的样本集进行分析。标准物质的分配将完全由NIST处理，辉钼矿标准物质的成本将仅反映NIST为其部分工作而产生的成本。***

0111876SteinUse of the geochronometer based on the decay of rhenium (Re) to osmium (Os) is rapidly expanding, and there are no reference materials certified by the National Institute of Standards and Technology (NIST) for inter-laboratory comparison. Advances in chemical and mass spectrometric procedures permit high precision determination of Re and Os, even on low-ppt level samples. Molybdenite (MoS2) is uniquely suited for the Re-Os chronometer because it commonly contains high concentrations of the parent Re and essentially no initial daughter Os. Thus, the decay of 187Re to 187Os yields precise ages, even in very young samples, without correction for initial Os. With increasing demand for Re-Os dating, particularly of molybdenite, the need for an accepted reference material for inter-laboratory comparison has become crucial. We propose to calibrate a Re-Os molybdenite reference material, working together with University of Alberta and NIST. The proposed Re-Os reference molybdenite is from Henderson, Colorado, the location of a well-studied molybdenum deposit. NIST will physically mix, split, and bottle the Henderson molybdenite powder. Statistically representative sets of samples will be analyzed by the AIRIE Lab at Colorado State University and by the isotope lab at the University of Alberta. The distribution of the reference material will be fully handled by NIST, and the cost for the molybdenite reference material will reflect only the costs incurred by NIST for their part of the work. ***