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Crustal structure beneath Montserrat, Lesser Antilles, constrained by xenoliths, seismic velocity structure and petrology

Kiddle, E.J.; Edwards, B.; Loughlin, S.C.; Petterson, M.; Sparks, R.S.J.; Voight, B.. 2010 Crustal structure beneath Montserrat, Lesser Antilles, constrained by xenoliths, seismic velocity structure and petrology. Geophysical Research Letters, 37, L00E11. 10.1029/2009GL042145

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Abstract/Summary

Noritic anorthosite, gabbroic anorthosite and hornblende‐gabbro xenoliths are ubiquitous in the host andesite at Montserrat. Other xenoliths include quartz diorite, metamorphosed biotite‐gabbro, plagioclase‐hornblendite and plagioclase‐clinopyroxenite. Mineral compositions suggest a majority of the xenoliths are cognate. Cumulate, hypabyssal and crescumulate textures are present. A majority of the xenoliths are estimated to have seismic velocities of 6.7–7.0 km/s for pore‐free assemblages. These estimates are used in conjunction with petrological models to constrain the SEA CALIPSO seismic data and the structure of the crust beneath Montserrat. Andesitic upper crust is interpreted to overlie a lower crust dominated by amphibole and plagioclase. Xenolith textures and seismic data indicate the presence of hypabyssal intrusions in the shallow crust. The structure of the crust is consistent with petrological models indicating that fractionation is the dominant process producing andesite at Montserrat.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1029/2009GL042145
Programmes: BGS Programmes 2010 > Earth hazards and systems
ISSN: 0094-8276
NORA Subject Terms: Earth Sciences
Date made live: 17 Jun 2010 13:58
URI: http://nora.nerc.ac.uk/id/eprint/10006

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