[SCG63-P13] Role of plutonics in the generation of felsic magmas at ocean island volcanoes — Oki Dozen and Ascension Island
Keywords:Volcanic-plutonic connection, Ocean island volcanism, Magma plumbing systems
We present whole rock XRF analyses, FTIR analyses of melt inclusions -and major and trace element concentrations within their host crystals- and textural information from BSE and CL images of crystal from the plutonic rocks from both Ascension Island and Oki Dozen. Our new data reveals that while the plutonic rocks from Ascension Island are generally more-evolved that the exposed volcanics, they still show no evidence for magma mixing or repeated use of a single storage region. While plutonics from Oki Dozen are of similar composition to the volcanic products, again there is no evidence for magma mixing in crystal textures, which is very different from the felsic magmas of the Canaries or IcelandI,III. Our data is used to highlight the importance of fractional crystallisation in the production of evolved magmas in ocean island volcanoes not directly related to any plate tectonic boundary, and reveals the importance of a pre-established crustal structure in the evolution of magmas in relatively thin oceanic crust.
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