Inter-element fractionation of highly siderophile elements in the Tonga Arc due to flux melting of a depleted source

Abstract

. (2012) 'Inter-element fractionation of highly siderophile elements in the Tonga Arc due to ux melting of a depleted source. ', Geochimica et Cosmochimica Acta., Further information on publisher's website:http://dx.doi.org/10.1016/j.gca.2012.03.025Publisher's copyright statement: NOTICE: this is the author's version of a work that was accepted for publication in Geochimica et Cosmochimica Acta. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reected in this document. Changes may have been made to this work since it was submitted for publication. A denitive version was subsequently published in Geochimica et Cosmochimica Acta, 89, 2012Acta, 89, , 10.1016Acta, 89, /j.gca.2012 Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. with a high fluid flux is thought to have produced boninitic magmas at several arc and FSC locations.As such, this arc system provides an opportunity to assess the fluid mobility of HSEs and to investigate the effects of fluid-induced melting and prior melt depletion on HSE behaviour during both mantle melting and magma evolution.

Highly siderophile element and 182 W evidence for a partial late veneer in the source of 3.8 Ga rocks from Isua, Greenland

“…Basaltic Isua samples have much higher HSE contents than MORB, but similar to modern-day arc samples, indicating sulphide undersaturated magma evolution (Dale et al, 2012). Such magma evolution makes it difficult to constrain the source HSE concentrations, but the data suggest a source which is approaching that of modern-day mantle and are consistent with the source defined by the ultramafics.…”

“…The analytical methods employed for HSE and Os isotope analysis follow closely those described in detail in Dale et al (2012). Briefly, sample powders (~1.5 g) were digested and equilibrated with a mixed HSE spike using inverse aqua regia (16 mol l -1 HNO 3 and 12 mol l -1 HCl in 2:1 proportions)…”

“…1, Table 1), indicating that these elements, with the exception of Re, have not been significantly affected by low-temperature or metamorphic processes since emplacement. The basaltic samples have strongly fractionated HSE patterns, depleted in Os-Ir-Ru and slightly enriched in Pd and Pt with respect to primitive mantle (henceforth referred to as BSE), with high Pt/Ru ratios which bear resemblance to modern arc volcanics (Dale et al, 2012). The retention of very high Pt and Pd concentrations at relatively low MgO content (Fig.…”

“…Given that there are examples of mantle-derived rocks which have higher Pt concentrations than their assumed mantle sources (e.g. Rehkämper et al, 1999;Puchtel and Humayun, 2005;Dale et al, 2012) Os/ 188 Os and HSE ratios, and the realisation that we do not possess the full range of chondrite compositions present during late accretion, all currently preclude more definitive conclusions on the precise composition of the late veneer (Walker, 2009). Thus, here we investigate the effects on HSE and 182 W of a range of late veneer compositions including the major chondrite groups and also a minor fraction of differentiated, iron meteorite-like material (~20%).…”

The effects of melt depletion and metasomatism on highly siderophile and strongly chalcophile elements: S–Se–Te–Re–PGE systematics of peridotite xenoliths from Kilbourne Hole, New Mexico

“…The HSE in this aqua regia fraction were subsequently separated and 303 recovered by anion-exchange column chemistry (AG1X-8 100-200 mesh) using the methods 304 described in detail in Dale et al (2008Dale et al ( , 2012 Briefly, 1 g of sample powder was desilicified, using HF and concentrated HNO 3 in a bench 333 top digestion procedure after complete digestion in inverse aqua regia using an Anton Paar 334 high pressure asher at 100 bar and 220 °C for 12 h. Selenium and tellurium were separated 335 using thiol cotton fibre (Yu et al, 1983) and non-cratonic), and tectonically-emplaced massifs.…”