Universität zu Köln

Bragagni, A., van Acken, D., Fonseca, R. O. C., Speelmanns, I. M., Wainwright, A. N., Heuser, A., Nowell, G. M. and Luguet, A. (2018). Re-Os and HSE in individual base metal sulfide grains: Evaluating micro-analytical procedures using a sulfide reference material. Chem. Geol., 493. S. 426 - 441. AMSTERDAM: ELSEVIER SCIENCE BV. ISSN 1878-5999

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Abstract

Two Fe-Ni sulfides, resembling the chemical composition of a typical mantle base metal sulfide (BMS), were synthesized and used to test micro-analytical procedures (sample digestion and chemical separation) to determine Os-187/Os-188 and highly siderophile element (HSE) mass fractions in single BMS grains. The bulk Os-187/Os-188 and HSE mass fractions of the synthetic sulfides were independently determined after high pressure asher (HPA) digestion and conventional HSE separation (Os solvent extraction and Ir, Ru, Pt, Pd, Re separation via anion exchange chromatography), while the homogenous distribution of HSE was assessed via LA-ICP-MS. Tests were performed following the protocol of Pearson et al. (1998), where sulfides are digested in H2SO4/CrO3 and Os is simultaneously extracted as OsO4. Additional tests were performed adding a pre-digestion step in HBr and/or HCl. The duration and the temperature of the pre-digestion and micro-distillation steps, as well as different chromatographic separations of the HSE were also evaluated. While the majority of the tests yielded Os-187/Os-188 in agreement with that obtained after HPA digestion, HSE mass fractions show large deviations from the reference content, depending on the used procedure. Such variations are interpreted as the result of incomplete sulfide digestion, Os spike loss, and the possible presence of undigested sub-micrometric platinum group minerals (PGM). Overall, the bulk sulfide HSE mass fractions obtained after HPA digestion are best reproduced (mean deviations <= 10%) using a pre-digestion step in HBr+HCl at 120 degrees C. This study highlights the need for matrix-matched sulfide reference materials for routine use in laboratories determining HSE mass fractions and Os isotope ratios on single BMS grains. Such an approach is fundamental for comparing and compiling Re-Os ages collected on BMS in many different laboratories. This study also demonstrates that there is need for further testing and for methodological developments/improvement of the analytical procedure(s) used for Re-Os dating and HSE mass fraction determinations in single BMS grains.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Bragagni, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED van Acken, D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Fonseca, R. O. C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Speelmanns, I. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wainwright, A. N. UNSPECIFIED UNSPECIFIED UNSPECIFIED Heuser, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Nowell, G. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Luguet, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-176225
DOI:	10.1016/j.chemgeo.2018.06.020
Journal or Publication Title:	Chem. Geol.
Volume:	493
Page Range:	S. 426 - 441
Date:	2018
Publisher:	ELSEVIER SCIENCE BV
Place of Publication:	AMSTERDAM
ISSN:	1878-5999
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language PLATINUM-GROUP ELEMENTS; IONIZATION MASS-SPECTROMETRY; HIGHLY SIDEROPHILE ELEMENTS; LA-ICP-MS; LASER-ABLATION; ISOTOPE SYSTEMATICS; MANTLE SULFIDES; PERIDOTITE XENOLITHS; LITHOSPHERIC MANTLE; ABYSSAL PERIDOTITES Multiple languages Geochemistry & Geophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/17622