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Differentiation and source processes at Mt Pelee and the Quill; active volcanoes in the Lesser Antilles Arc.

Davidson, J.P. and Wilson, B.M. (2011) 'Differentiation and source processes at Mt Pelee and the Quill; active volcanoes in the Lesser Antilles Arc.', Journal of petrology., 52 (7-8). pp. 1493-1531.

Abstract

Volcanic rocks erupted at Mt Pelée (Martinique; central Lesser Antilles) and the Quill volcano (Statia; northern Lesser Antilles) define distinct differentiation trends, each of which can be accounted for largely by fractional crystallization of plagioclase, amphibole and Fe–Ti oxides. This assemblage is seen commonly in associated cumulate nodules, although the petrography of the lavas is pyroxene + plagioclase + Fe–Ti oxides. Thus differentiation is controlled, in part, by cryptic amphibole fractionation. At a given degree of differentiation incompatible trace element abundances tend to be higher at Mt Pelée, and REE patterns are more fractionated than is the case at the Quill. Isotopic ratios of Sr and Pb correlate with indices of differentiation (e.g. wt % SiO2) at both volcanoes (more convincingly at Mt Pelée), indicating that differentiation is also an open-system process. When the differentiation trends for the two volcanoes are compared they do not converge towards a single parental magma composition, suggesting that the primary magmas for the Quill and Mt Pelée are different. This difference is most probably due to mantle source variations. The source of the Mt Pelée magmas appears to be more enriched in incompatible elements, consistent with a greater proportion of admixed subducted sediment. This observation is in agreement with previous studies that have documented an increasing sediment contribution southwards along the arc. However, comparison with available data for other volcanoes along the arc does not reveal a consistent along-arc trend, suggesting that a model of sediment–source mixing is oversimplified and that additional factors such as variable fluid contributions from the subducted slab may be important.

Item Type:Article
Keywords:Amphibole, Differentiation, Island arc, Lesser Antilles.
Full text:PDF - Accepted Version (1106Kb)
Status:Peer-reviewed
Publisher Web site:http://dx.doi.org/10.1093/petrology/egq095
Publisher statement:This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Journal of petrology following peer review. The definitive publisher-authenticated version Davidson, J.P. and Wilson, B.M. (2011) 'Differentiation and source processes at Mt Pelee and the Quill; active volcanoes in the Lesser Antilles Arc.', Journal of petrology., 52 (7-8). pp. 1493-1531 is available online at: http://dx.doi.org/10.1093/petrology/egq095
Record Created:25 Nov 2011 14:05
Last Modified:02 Mar 2012 10:24

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