Chapter 18 Characterization of mafic enclaves in the erupted products of Soufrière Hills Volcano, Montserrat, 2009 to 2010

Melissa Plail, Jenni Barclay, Madeleine C. S. Humphreys, Marie Edmonds, Richard A. Herd, Thomas E. Christopher
2014 Geological Society of London Memoirs  
Citation for published item: lilD wF nd frlyD tF nd rumphreysD wFgFF nd idmondsD wF nd rerdD FeF nd ghristopherD FiF @PHIRA 9ghrteriztion of m( enlves in the erupted produts of oufri ere rills olnoD wontserrtD PHHW to PHIHF9D wemoirsFD QW F ppF QRQEQTHF Further information on publisher's website: httpXGGdxFdoiForgGIHFIIRRGwQWFIV Publisher's copyright statement: qeologil oiety of vondon PHIR Additional information: he iruption of oufri ere rills olnoD wontserrt from PHHH to PHIHF ghpter IVF Use
more » ... olicy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full DRO policy for further details. Abstract 14 Lavas from the current eruption of the Soufrière Hills Volcano, Montserrat exhibit evidence 15 for magma mingling, related to the intrusion of mafic magma at depth. We present detailed 16 field, petrological, textural and geochemical descriptions of mafic enclaves in andesite 17 erupted during 2009-2010, and subdivide the enclaves into three distinct types. Type A are 18 mafic, glassy with chilled margins and few inherited phenocrysts. Type B are more evolved 19 with high inherited phenocryst contents and little glass, and are interpreted as significantly 20 hybridised. Type C are composite, with a mafic interior (type A) and a hybrid exterior (type 21 B). All enclaves define tight linear compositional trends, interpreted as mixing between a 22 Number of figures: 12 32 Number of references: 61 33 Abbreviated title: Mafic enclaves at SHV 34 35 The process of magma mingling, where two or more magmas mix incompletely 36 during magma storage in the crust, is commonly associated with arc volcanism (e.g. Pallister 37 et al. 1992; Clynne 1999) and results in the formation of banded pumice and magmatic 38 mafic enclaves (e.g. Bacon 1986; Clynne 1999; Browne et al. 2006b; Martin et al. 2006b). 39 More complete mixing of magmas is inhibited by large contrasts in viscosity and density, 40 reflecting differences in temperature, composition and crystallinity, and the relative 41
doi:10.1144/m39.18 fatcat:nse5mfie4zfcdbonkiamlja2zi