Peridotite xenoliths from Grenada, Lesser Antilles island arc

I. J. Parkinson, R. J. Arculus*, S. M. Eggins

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

103 Citations (Scopus)

Abstract

Ultramafic xenoliths comprising harzburgite, lherzolite (reacted harzburgite) and spinel-rich dunite, occur in alkali olivine basalts (M series) of Grenada in the Lesser Antilles island arc. Textures are protogranular, porphyroclastic and granular; the latter are restricted to dunites and areas of the harzburgites/lherzolites where interaction with host magma has occurred. Primary mineralogy comprises olivine, orthopyroxene, clinopyroxene, and spinel. Harzburgites are residual from a fractional partial melting event totaling ∼ ≤ 22%. Infiltration of harzburgite by (and reaction with) basalt has produced: a wehrlite, with partial dissolution of primary spinel, an increase in the oxygen fugacity (fO2) from primary values 1-2 log fO2 units above the fayalite-magnetite-quartz (FMQ) buffer, to 2-2.5 log units above the buffer; reaction of orthopyroxene to form patches of intergrown olivine and clinopyroxene, and bronzite andesite glass (60 wt%, SiO2 18-20 wt% Al2O3 and 3-4 wt% Na2O) with flat to light rare earth element-depleted, chondrite-normalized abundances. Refertilisation of the mantle by reacting melts, producing a clinopyroxene-rich lithology, may form a source of ankaramitic (high-Ca) arc basalts.

Original languageEnglish
Pages (from-to)241-262
Number of pages22
JournalContributions to Mineralogy and Petrology
Volume146
Issue number2
DOIs
Publication statusPublished - 1 Nov 2003

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