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Methodology and Application of Hafnium Isotopes in Ilmenite and Rutile by MC ‐ ICP ‐ MS
Author(s) -
Morisset CarolineEmmanuelle,
Scoates James S.,
Weis Dominique,
Rahier André
Publication year - 2014
Publication title -
geostandards and geoanalytical research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.037
H-Index - 73
eISSN - 1751-908X
pISSN - 1639-4488
DOI - 10.1111/j.1751-908x.2013.00207.x
Subject(s) - ilmenite , rutile , hafnium , anorthosite , chemistry , titanium , analytical chemistry (journal) , isotope dilution , geology , mineralogy , mass spectrometry , zirconium , inorganic chemistry , environmental chemistry , chromatography , quartz , paleontology , organic chemistry , plagioclase
The high abundances of the high field‐strength elements in ilmenite and rutile make these minerals particularly suitable for hafnium isotopic investigations. We present a technique for separating Hf by ion exchange chemistry from high‐TiO 2 (> 40% m/m) minerals to achieve precise Hf isotopic composition analyses by MC (multiple collector)‐ ICP ‐ MS . Following digestion and conversion to chlorides, the first elution column is used to separate iron and the rare earth elements, the second column is designed to separate most of the titanium from Hf, an evaporation step using HC lO 4 is then performed to remove any trace of HF in preparation for the third column, which is needed to eliminate any remaining trace of titanium. The modified chemistry helped to improve the yields from < 10 to > 78% as well as the analytical precision of the processed samples (e.g., sample 2033‐ A 1, 176 H f/ 177 H f = 0.282251 ± 25 before vs. 0.282225 ± 6 after). The technique was tested on a case study in which the H f isotopic ratios of ilmenite and rutile (analysed prior to the chemistry improvement) were determined and permitted to evaluate that the origin of rutile‐bearing ilmenite deposits is from the same or similar magma than their, respectively, associated Proterozoic anorthosite massifs ( S aint‐ U rbain and L ac A llard) of the Grenville P rovince in Q uébec, C anada.