Zambardi, T.; Poitrasson, F.; Quitte, G. and Anand, M.
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A fluorhydric acid-free sample preparation method derived from Georg et al.  has been used to measure the natural variations of silicon isotope compositions in terrestrial (including 12 geological standard materials) and meteoritic bulk-rock samples. All measurements were done using a Neptune MC-ICPMS in medium resolution mode (m/Δm = 7000, peak-edge definition). Magnesium was used as internal standard for mass-bias drift correction. The δ30Si values are expressed relative to the NBS-28 silica standard. IRMM-17 reference material yields a δ30Si of -1.4‰ ± 0.05‰ (2SD, n=11) in agreement with previous data [2-3]. Long-term reproducibilities were obtained for BHVO-2 (δ30Si = -0.27‰ ± 0.08‰ (2SD, n=30)) and a in-house Si standard (δ30Si = -0.01‰ ± 0.07‰ (2SD, n=20)) on a 7 months time scale. Total variation of δ30Si in natural samples ranges from - 0.5‰ to -0.1‰. Comparison with δ29Si values shows that this isotopic fractionation is mass-dependent. A 0.2‰ isotopic variation occurs among terrestrial samples suggesting an enrichment in the heavier silicon isotopes as a function of magma differentiation, as initially hinted by Douthitt . Terrestrial samples mean value (δ30SiEarth= -0.23‰) is heavier by about 0.24‰ in δ30Si compared to chondrites. This may be explained by silicon isotope fractionation during planetary accretion and/or differentiation.
|Item Type:||Conference Item|
|Copyright Holders:||2009 Not known|
|Academic Unit/Department:||Science > Physical Sciences|
|Interdisciplinary Research Centre:||Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)|
|Depositing User:||Patricia Taylor|
|Date Deposited:||02 Feb 2012 16:38|
|Last Modified:||23 Oct 2012 14:40|
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