KORICH, Dan ('00) (Advisor: Karen Harpp)
The current geographic location of Genovesa between the Galapagos Spreading Center and the Galapagos Hotspot provides a unique opportunity to refine theories regarding the interaction of plumes and adjacent mid-ocean ridges. The geochemistry of a series of samples representing the entire subaeriel exposure of Genovesa, a small island on the northeast corner of the Galapagos platform, show an extremely close resemblance to mid-ocean ridge basalt from the adjacent Galapagos Spreading Center. The emergence of Genovesa as an intraplate island consisting of mid-ocean ridge basalts is significant to understand phenomenon unique to the Galapagos region.
The Galapagos Islands are believed to have formed from a mantle plume, also known as a hotspot, which has risen from the deep mantle up through the oceanic lithosphere. Never the less, the geochemical compositions of Galapagos basalts are inconsistent with deep, mantle-derived material, contradicting the typical hotspot model. Isotopic, trace, and major element data from the Galapagos Island suggest that at least two mantle sources have mixed to form the Galapagos platform. The Galapagos Plume, geographically centered on the western edge of the Galapagos Islands, and the Galapagos Spreading Center, an active mid-ocean ridge located 100 km to the north-east of the mantle plume, are believed to be the primary contributors of mantle material. Genovesa appears to represent the depleted end member in this regional mixing system.
