Petrogenesis of the Galapagos Islands: A Case Study at Fernandina and Pinta Volcanoes

The Galapagos Islands, located in the South Pacific Ocean, are comprised of 18 major volcanic islands. The archipelago has a rich tectonic history, situated atop a hotspot and a nearby mid ocean ridge, the Galapagos Spreading Center (GSC). While there are 18 major islands in the Galapagos, this study focuses on two; Fernandina, one of the largest and youngest islands which is situated atop the hotspot, and Pinta, a smaller, older island closer to the GSC. The full petrologic histories of these two volcanoes are not known, and it is unclear whether the eruptions at Fernandina and Pinta share the same magmatic origin and eruptive sequence. We report new compositional data of 29 different submarine basaltic glasses from Fernandina and Pinta. Major and trace elements were collected at Boise State University, using EPMA and LA-ICPMS respectively. Compared to previously reported data in the literature, our data is slightly more homogenous, but distinctive between the two islands. Petrologic modeling of both major and trace elements will be done to determine the influence of the magmatic processes of fractional crystallization, magma mixing, and partial melting of the mantle in order to constrain the lavas’ petrogenesis.