期刊
JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY
卷 36, 期 8, 页码 1643-1656出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/d1ja00125f
关键词
-
资金
- Natural Science Foundation of China [91855209, 41525012, 41672065, 41902037]
- Key Research Program of the Institute of Geology & Geophysics, CAS [IGGCAS-201902]
Columbite-group minerals (CGMs) with high Hf contents are suitable for Lu-Hf isotope analysis, providing insights into their sources in rare-metal deposits. The study evaluated the impact of tantalum on Hf isotope measurements and proposed improved analytical methods for accurate results.
Due to their relatively high Hf contents (i.e., several hundreds to thousands of ppm), columbite-group minerals (CGMs) are suitable for Lu-Hf isotope analysis, which can provide new insights into the source of such minerals in combination with the U-Pb age of rare-metal deposits. However, few studies have reported Lu-Hf isotope data for CGMs. Tantalum is a major element in CGMs (12-48 wt% Ta2O5) and has a significant effect on measurements of Hf isotopes using MC-ICP-MS. This effect was first evaluated in this study by analysis of mixed Hf-Ta standard solutions with different Ta/Hf ratios and LA-MC-ICP-MS analysis of various CGMs. This analytical artifact reflects serious tailing of the large Ta-181 signal onto the Hf-180 and Hf-179 masses during analysis. Therefore, in order to obtain accurate Hf isotope data for CGMs by MC-ICP-MS, we present an improved chemical separation procedure for Hf from Ta, and also a novel analytical protocol for LA-MC-ICP-MS analysis of CGMs. Accurate in situ(176)Hf/Hf-177 ratios for CGMs can be obtained by normalization to Hf-178/Hf-177 = 1.4672, rather than Hf-179/Hf-177 = 0.7325, using the exponential law. This approach was validated by solution and laser ablation MC-ICP-MS analysis of four CGM samples from China and Africa. The Lu-Hf isotopic composition of CGMs provides a new geochemical tracer for rare-metal deposits.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据