Trace Elements in Icelandic Rhyolite

Jason Keiser (MS Candidate – U. Mass)

I am using the full array of chemical analytical techniques to characterize individual basalt flows as well as felsic ash flows from an 8-9 million year old Oxnadalur bimodal volcanic complex in north-central Iceland.  Felsic eruptions in Iceland are rare, but can be quite voluminous.  Many studies have taken advantage of the great exposures to determine how felsic material can be generated in a setting otherwise dominated by mafic material, such as the oceanic crust.  The most common models have suggested fractional crystallization of a mafic source or partial melting of subsided extrusives as well as remelting of silicic segregations formed within the upper parts of solidifying basaltic intrusions beneath long lived central volcanoes.  Our goal is to combine major and trace element trends with REE trends and isotopic data to determine the role of fractional crystallization and partial melting in the evolution of the magma at the Oxnadalur complex.