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Geochemical Source Components In Seafloor Lavas In The Aleutian Back-Arc, Max Thomas Siegrist

Theses and Dissertations

Whole-rock compositions of seafloor lavas are used to constrain the processes and source characteristics contributing to the formation of geochemically distinctive, primitive magma types located in the Aleutian back-arc. Samples were dredged primarily from small volcanic cones on the seafloor, located between the emergent volcanoes and in the back-arc up to 60 km from the volcanic front. Compositions vary from basalt to dacite, with 48-70 % SiO₂ and 4-13 % MgO. Nearly 30% of the samples are primitive, with Mg/Mg+Fe >0.60. Most primitive samples are basalts, which fall into two groups, based on minor and trace element abundances. Low/med-K …