CONSTRAINING CRUST FORMATION AT SLOW-SPREADING RIDGES USING THE COMPOSITION AND MORPHOLOGY OF MT. EGGVIN

Mt. Eggvin is a large, discrete volcanic seamount located at 70.948ºN/13.035°W on the eastern wall of the axial valley of the Northern Kolbeinsey Ridge (NKR). It is the largest volcanic feature on the anomalously shallow Eggvin Bank. The magma source for the NKR is characterized by long-term chemical and isotopic enrichment, but the origin of the enriched source is has been the subject of debate. Three possible source origins are: (1) a trapped remnant of Icelandic plume material, (2) magma associated with or mixed with a small plume, and (3) a small microplate of rifted Greenland lithospheric mantle material. In this first detailed study of the composition and morphology of Mt. Eggvin, seven basaltic samples, including two popping rock basalts and five glassy separates, have been selected for trace elements and isotopic analysis. These geochemical results will help distinguish between the three petrogenesis possibilities outlined above. The new geochemical data are accompanied by bathymetric mapping and image analysis of Mt. Eggvin in order to constrain the effects of localized high magma supply on a slow-spreading ridge overlying heterogeneous mantle.