EarthRef.org Reference Database (ERR) -- Parkinson et al. 1998

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Parkinson et al. 1998

Parkinson, I.J., Hawkesworth, C.J. and Cohen, A.S. (1998). Ancient mantle in a modern arc: Osmium isotopes in Izu-Bonin-Mariana forearc peridotites. Science 281(5385): 2,011-2,013.

Mantle peridotites drilled from the Izu-Bonin-Mariana forearc have unradiogenic Os-187/Os-188 ratios (0.1193 to 0.1273), which give Proterozoic model ages of 820 to 1230 million years ago. If these peridotites are residues from magmatism during the initiation of subduction 40 to 48 million years ago, then the mantle that melted was much more depleted in incompatible elements than the source of mid-ocean ridge basalts (MORB). This result indicates that osmium isotopes record information about ancient melting events in the convecting upper mantle not recorded by incompatible Lithophile isotope tracers. Subduction zones may be a graveyard for ancient depleted mantle material. and portions of the convecting upper mantle may be less radiogenic in osmium isotopes than previously recognized.

BACKGROUND DATA FILES

	Abstract

	Table 1

Keywords
archean lithospheric mantle, re-os, abyssal peridotites, depleted mantle, systematics, xenoliths, evolution, craton, morb, nd

Journal
Science
http://www.sciencemag.org/

Publisher
American Association for the Advancement of Science
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