Geochemistry of olivine-hosted and plagioclase-hosted melt inclusions in basalts from Deception Island

Abstract

Bransfield Strait is located between Antarctic Peninsula and South Shetland Islands and also have Back Arc Basin(BAB) and rift. Deception Island is westernmost in Bransfield Strait and previous study is geophysics and geochemistry of whole rocks. Melt inclusions are more informative about primitive magma source and early magma history than whole rocks. Melt inclusions from Deception Island were sampled in olivine and plagioclase from basalts. Most melt inclusions are heterogeneity and thus are necessary homogenization experiment. Homogenization experiment have a problem with oxidizied minerals in high temperature. To prevent this phenomenon, Furnace using Ar gas was heated to high temperature(1250℃) for 1-2 hours and then quenched to succeed homogenization. In comparison of MgO versus SiO2, Al2O3, FeO, and TiO2 in olivine-hosted melt inclusions indicate from early magma evolution rather than plagioclase-hosted melt inclusions. U Pb Sr in melt inclusion are more enriched than N-MORB because it may have been influenced by magma affected by the arc component. However, some melt inclusions have a similar tendency to N-MORB, which is similar to whole rocks analysis. In addition, large ion lithopile elements in melt inclusions(like to Sr, Pb) are more abundant than high field strength elements (like to Nb, Ta) in melt inclusions. It seems to have been influenced by the material of the surrounding trench. We will analyze Pb isotope in melt inclusions and thus expect to clearly indicate magma source and early magma events