Geochemical and petrological studies of lavas, pyroclastica and associated xenoliths from the Christiana Islands, Aegean Sea

Abstract

Geochemical and petrological investigations of the volcanic islands of Christiana proved their genetic connection with the calc-alkaline volcanism of the Santorini group and the submarine Kolombos volcano. The lavas of Christiana range from andesite to dacite while pumice is of rhyolithic chemistry. Rather constant K/Rb ratios indicate consanguine magmas. Increased Ni, Cr and Mg concentrations in several lavas indicate a certain admixture of peridotite material to the calc-alkaline magmas. Xenoliths found below an autochthonous pumice layer prove penetration of granites, phyllites and limestone by the rising magma. The geochemical investigations support a subduction type origin of the volcanic material of the Christiana Islands