The University of Southampton
University of Southampton Institutional Repository

Distribution of platinum group elements and rhenium between metallic phases of iron meteorites

Distribution of platinum group elements and rhenium between metallic phases of iron meteorites
Distribution of platinum group elements and rhenium between metallic phases of iron meteorites
In situ measurement of the platinum group elements (PGE) and Re by laser ablation-ICPMS allows fractionation patterns to be established between host (kamacite) and Ni-rich exsolved phases (taenite and plessite). Measurements on two IAB iron meteorites (Canyon Diablo and Odessa) show that, for the Ni-rich phases: (a) there is no significant fractionation for Ru and Rh; (b) Pd is enriched; and (c) Ir, Os and Pt are strongly depleted. We suggest that, in the case of kamacite, taenite and plessite, the controlling mechanism is ionic size with the order of ions (small to large) being Ir-Os-Pt-(Re)-Rh-Ru-Pd. This progression plots as a smooth curve on a diagram of relative abundance distribution vs. ionic size.

A comparison of PGE and Re data on iron meteorites with published data from CI chondrites indicate that there is little or no relative fractionation between the elements. The exception is Re that is clearly enriched in kamacite relative to chondrites. This confirms earlier observations on the fractionation of Re/Os between bulk IAB irons and CI values [1].

Metallic veins cutting graphite inclusions within the Canyon Diablo IAB meteorite are interpreted as a melt fraction from the iron meteorite. Abundance ratios for PGE and Re between kamacite and the metallic vein are similar to abundance ratios between kamacite and Ni-rich phases. The fact that those elements with large ionic radii (Rh, Ru and Pd) are concentrated in the metallic veins adds weight to the view that they represent a melt fraction.

Our in situ measurements of the PGE and Re demonstrate that elemental fractionation takes place both during melt segregation and solid state diffusion (exsolution). The data have important implications for the Re/Os geochronometer and indicate that measurements of187Os/186Os ratios on individual phases within iron meteorites may provide a potential mineral isochron.
platinum group, iron meteorites, chemical fractionation, inductively coupled plasma methods, mass spectroscopy, laser methods
0012-821X
11-24
Hirata, Takafumi
5a70f814-c049-4e16-9954-1108e17fc8be
Nesbitt, Robert W.
6a124ad1-4e6d-4407-b92f-592f7fd682e4
Hirata, Takafumi
5a70f814-c049-4e16-9954-1108e17fc8be
Nesbitt, Robert W.
6a124ad1-4e6d-4407-b92f-592f7fd682e4

Hirata, Takafumi and Nesbitt, Robert W. (1997) Distribution of platinum group elements and rhenium between metallic phases of iron meteorites. Earth and Planetary Science Letters, 147 (1-4), 11-24. (doi:10.1016/S0012-821X(97)00012-5).

Record type: Article

Abstract

In situ measurement of the platinum group elements (PGE) and Re by laser ablation-ICPMS allows fractionation patterns to be established between host (kamacite) and Ni-rich exsolved phases (taenite and plessite). Measurements on two IAB iron meteorites (Canyon Diablo and Odessa) show that, for the Ni-rich phases: (a) there is no significant fractionation for Ru and Rh; (b) Pd is enriched; and (c) Ir, Os and Pt are strongly depleted. We suggest that, in the case of kamacite, taenite and plessite, the controlling mechanism is ionic size with the order of ions (small to large) being Ir-Os-Pt-(Re)-Rh-Ru-Pd. This progression plots as a smooth curve on a diagram of relative abundance distribution vs. ionic size.

A comparison of PGE and Re data on iron meteorites with published data from CI chondrites indicate that there is little or no relative fractionation between the elements. The exception is Re that is clearly enriched in kamacite relative to chondrites. This confirms earlier observations on the fractionation of Re/Os between bulk IAB irons and CI values [1].

Metallic veins cutting graphite inclusions within the Canyon Diablo IAB meteorite are interpreted as a melt fraction from the iron meteorite. Abundance ratios for PGE and Re between kamacite and the metallic vein are similar to abundance ratios between kamacite and Ni-rich phases. The fact that those elements with large ionic radii (Rh, Ru and Pd) are concentrated in the metallic veins adds weight to the view that they represent a melt fraction.

Our in situ measurements of the PGE and Re demonstrate that elemental fractionation takes place both during melt segregation and solid state diffusion (exsolution). The data have important implications for the Re/Os geochronometer and indicate that measurements of187Os/186Os ratios on individual phases within iron meteorites may provide a potential mineral isochron.

Full text not available from this repository.

More information

Published date: March 1997
Keywords: platinum group, iron meteorites, chemical fractionation, inductively coupled plasma methods, mass spectroscopy, laser methods
Organisations: Geochemistry

Identifiers

Local EPrints ID: 361639
URI: https://eprints.soton.ac.uk/id/eprint/361639
ISSN: 0012-821X
PURE UUID: 883d8c77-7295-4771-807a-f2f5fa93a4ac

Catalogue record

Date deposited: 28 Jan 2014 13:35
Last modified: 16 Jul 2019 21:13

Export record

Altmetrics

Contributors

Author: Takafumi Hirata
Author: Robert W. Nesbitt

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×