Highly siderophile element geochemistry of peridotites and pyroxenites from Horní Bory, Bohemian Massif: Implications for HSE behaviour in subduction-related upper mantle

Ackerman, Lukáš; Pitcher, L.; Strnad, L.; Puchtel, I. S.; Jelínek, E.; Walker, R. J.; Rohovec, Jan

doi:https://dx.doi.org/10.1016/j.gca.2012.09.050

Number of the records: 1

Highly siderophile element geochemistry of peridotites and pyroxenites from Horní Bory, Bohemian Massif: Implications for HSE behaviour in subduction-related upper mantle

1.

SYSNO ASEP	0388155
Document Type	J - Journal Article
R&D Document Type	Journal Article
Subsidiary J	Článek ve WOS
Title	Highly siderophile element geochemistry of peridotites and pyroxenites from Horní Bory, Bohemian Massif: Implications for HSE behaviour in subduction-related upper mantle
Author(s)	Ackerman, Lukáš (GLU-S)_{RID, SAI, ORCID} Pitcher, L. (US) Strnad, L. (CZ) Puchtel, I. S. (US) Jelínek, E. (CZ) Walker, R. J. (US) Rohovec, Jan (GLU-S)_{RID, SAI}
Source Title	Geochimica et Cosmochimica Acta. - : Elsevier - ISSN 0016-7037 Roč. 100, č. 1 (2013), s. 158-175
Number of pages	18 s.
Publication form	WWW - WWW
Language	eng - English
Country	GB - United Kingdom
Keywords	alloy ; high pressure ; high temperature ; igneous geochemistry ; isotopic composition ; mass balance ; nappe ; osmium isotope ; peridotite ; petrography ; platinum group element ; precipitation (chemistry) ; pyroxenite ; siderophile element ; subduction ; sulfide ; upper mantle
Subject RIV	DD - Geochemistry
R&D Projects	KJB300130902 GA AV ČR - Academy of Sciences of the Czech Republic (AV ČR)
Institutional support	GLU-S - RVO:67985831
CEZ	AV0Z30130516 - GLU-S (2005-2011)
UT WOS	000312102100009
EID SCOPUS	84869475726
DOI	10.1016/j.gca.2012.09.050
Annotation	Highly siderophile element (HSE - Re, Os, Ir, Ru, Rh, Pd, Pt, and Au) and S abundances, sulphide petrography and ¹⁸⁷Os/¹⁸⁸Os compositions of two distinct suites - Mg-lherzolite and Fe-dunite/wehrlite accompanied by pyroxenites from Horní Bory, Bohemian Massif, Czech Republic are reported. The Mg-lherzolite suite is enriched in IPGE (Os, Ir, and Ru), moderately depleted in Pd, Pt and S, and has osmium isotopic compositions similar to that of the Phanerozoic convecting mantle. Such a composition can be best explained by reaction between previously depleted peridotite and sulphur-undersaturated melt at low melt-rock ratios. This reaction was associated with precipitation of IPGE alloys and Pt-As. The Fe-dunite/wehrlite suite is depleted in IPGE, enriched in Pd, Pt, and S and has radiogenic osmium isotopic compositions. The origin of this suite reflects melt-rock reaction between peridotite and subduction-related melt at high melt/rock ratios resulting in breakdown of primary sulphides and their replacement by HSE-poor but ¹⁸⁷Os-enriched sulphides. Mass-balance calculations and relations between HSE and S contents show that, while most of the Re is trapped in base metal sulphides (BMS), only up to 28% of the rest of the HSE (Os, Ir, Ru, Pd, Pt) are accommodated in BMS. Several Pt-As phases discovered in Mg-lherzolite and Fe-dunite/wehrlite and Os-Ru phase found in Mg-lherzolite suggesting complex behaviour of HSE during melt-rock reactions depending on melt composition and melt/rock ratios. The Re-Os data for the Fe-wehrlite/dunite and pyroxenite rocks yield an errorchon age of 334±19Ma, which is similar to the age of other high temperature/pressure rocks from Gföhl Nappe (Moldanubian Zone, Bohemian Massif); this age likely corresponds to the time of melt-rock reactions and subduction.
Workplace	Institute of Geology
Contact	Jana Popelková, popelkova@gli.cas.cz, Sabina Janíčková, Tel.: 233 087 272
Year of Publishing	2013

Number of the records: 1