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Geochemistry of diogenites: still more diversity in their parental melts

Barrat, J. A.; Yamaguchi, A.; Greenwood, R. C.; Benoit, M.; Cotten, J.; Bohn, M. and Franchi, I. A. (2008). Geochemistry of diogenites: still more diversity in their parental melts. Meteoritics and Planetary Science, 43(11) pp. 1759–1775.

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Abstract

We report on the major and trace element abundances of 18 diogenites, and O-isotopes for 3 of them. Our analyses extend significantly the diogenite compositional range, both in respect of Mg-rich (e.g., Meteorite Hills [MET] 00425, MgO = 31.5 wt%) and Mg-poor varieties (e.g., Dhofar 700, MgO = 23 wt%). The wide ranges of siderophile and chalcophile element abundances are well explained by the presence of inhomogeneously distributed sulfide or metal grains within the analyzed chips. The behavior of incompatible elements in diogenites is more complex, as exemplified by the diversity of their REE patterns. Apart from a few diogenite samples that contain minute amounts of phosphate, and whose incompatible element abundances are unlike the orthopyroxene ones, the range of incompatible element abundances, and particularly the range of Dy/Yb ratios in diogenites is best explained by the diversity of their parental melts. We estimate that the FeO/MgO ratios of the diogenite parental melts range from about 1.4 to 3.5 and therefore largely overlap the values obtained for non-cumulate eucrites. Our results rule out the often accepted view that all the diogenites formed from parental melts more primitive than eucrites during the crystallization of a magma ocean. Instead, they point to a more complex history, and suggest that diogenites were derived from liquids produced by the remelting of cumulates formed from the magma ocean.

Item Type: Journal Item
Copyright Holders: 2008 The Meteoritical Society
ISSN: 1086-9379
Keywords: HED meteorites; rare earth element (REE); trace elements; geochemistry
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Item ID: 21331
Depositing User: Richard Greenwood
Date Deposited: 14 May 2010 12:32
Last Modified: 07 Dec 2018 09:35
URI: http://oro.open.ac.uk/id/eprint/21331
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