[SVC41-P01] Magma mixing triggering eruption of deep rhyolite at Ascension Island, south Atlantic
Keywords:Magma mixing, Ocean island volcano, Crustal melting
In this contribution we present field observations, whole rock geochemical data, in situ mineral and melt inclusions analyses and textural characterisation of this unique mingled fall deposit from Ascension Island. This data is used to test the importance of fractional crystallisation vs. anatexis in generating the rhyolitic end-member of the mingled fall deposit, given that high water concentrations in melt inclusions are suggestive of formation at or near the Moho. Petrological data are used to infer multiple magmatic origins for the crystals. Glass and crystal compositional data is combined with textural observations to infer relatively short mingling to eruption timescales, on the order of days. The location of magma storage regions, and potential unrest timescales are particularly important on the populated Ascension Island where the nearest inhabited land mass is 1600 km away.
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