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Magma hybridisation and diffusive exchange recorded in heterogeneous glasses from Soufrière Hills Volcano, Montserrat
Author(s) -
Humphreys M. C. S.,
Edmonds M.,
Christopher T.,
Hards V.
Publication year - 2010
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2009gl041926
Subject(s) - mafic , geology , silicic , andesite , volcano , geochemistry , magma , igneous differentiation , mixing (physics) , volcanic rock , petrology , physics , quantum mechanics
Arc volcanoes commonly show evidence of mixing between mafic and silicic magma. Melt inclusions and matrix glasses in andesite erupted from Soufrière Hills Volcano, Montserrat, include an anomalously K 2 O‐rich population which shows close compositional overlap with residual glass from mafic inclusions. We suggest that these glasses represent the effects of physical mixing with mafic magma, both during ascent and by diffusive exchange during the formation of mafic inclusions. Many glasses are enriched only in K 2 O, suggesting diffusive contamination by high‐K mafic inclusion glass; others are also enriched in TiO 2 , suggesting physical mixing of remnant glass. Some mafic inclusion glasses have lost K 2 O. The preservation of this K‐rich melt component in the andesite suggests short timescales between mixing and ascent. Diffusive timescales are consistent with independent petrological estimates of magma ascent time.