同步辐射X荧光法分析矿物流体包裹体若干问题的探讨

本实验的目的是研究北京同步辐射装置 (BSRF)的 XRF实验装置对地质样品中的元素、特别是对轻元素的检测能力 ,并探讨利用目前这套装置检测流体包裹体样品时的若干问题。样品是以国家标准物质GBW0 710 6为基体 ,加入一定量的 Na Cl、 KCl,混合均匀后压制成的厚样片。测量在 BSRF的 XRF实验站进行 ,储存环电流约为 40 m A。样品与 Si(L i)半导体探测器的距离为 2 cm,同步辐射源的束斑为 2 0× 2 0 μm2。实验在大气条件下进行 ,采谱时间为 2 0 0秒。计算了各元素的相对检出限、采样深度、采样量和绝对量检出限 (达 10 - 8～ 10 - 1 0 g) ;并讨论了现有条件下分析流体包裹体样品时的可测量元素范围、包裹体深度的测量方法及深度对元素 XRF强度的影响、实验设备的最佳几何配置等问题。

Discussions on Some Problems Related to Fluid Inclusion Analysis by SXRF

X-ray fluorescence experiments were carried out at Beijing Synchrotron Radiation Facilities (BSRF) using synchrotron radiation as excitation source. The samples were made by mixing national reference standard GBW07106 and certain amount of reagent NaCl and KCl, and pressed into pellets. The purpose of the experiment is to verify the detection ability of the XRF setup at BSRF for elements in geological samples, especially for light elements. The beam size was 20 x 20 microns2, and the current in the storage ring was about 40 mA. The gap between the sample and the Si(Li) detector was 2 cm. With measuring time of 200 sec., The relative and absolute detection limits for 10 elements have been calculated. The sampling depth and sampling weight, which are critical in individual fluid inclusion analysis, have also been estimated. Some problems concerning the individual fluid inclusion analysis by SXRF, such as inclusion depth determination, effect of the inclusion depth on XRF intensity etc., are discussed based on the experiment results.