The generation of felsic magmas in the oceanic crust: assimilation-fractional crystallization processes versus re-melting of the crust

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The aim of the proposal is a combined geochemical and experimental petrological study of the formation of felsic magmas within the oceanic crust which will help to understand 1) fractionation processes leading to felsic crustal material, 2) the dynamics of magma ascent in the oceanic crust, and 3) the interaction of magmas with hydrothermally altered wall rocks. Firstly, we suggest to study in detail felsic magmatic rocks of the Oman Ophiolite as well as related mafic rocks which could represent parental magmas and hydrothermally altered wall rocks which may have been assimilated by evolving magmas or may have been partially molten to yield the felsic melts. Secondly, we will study a suite of basaltic, andesitic and dacitic lavas from the Pacific-Antarctic Rise, a fast-spreading ridge with abundant felsic volcanism. We intend to perform geochemical and isotopic analyses on the whole rocks, volcanic glasses, phenocrysts and xenocrysts in the samples and use the representative samples for the experimental study to define mineral-liquid equilibria, trace element partition coefficients, and possible melting or crystallization relationships. These two different approaches will be carried out by two PhD students who will work closely together and use the same sample material.