Petrological evidence of a typical oceanic crust in the western Mediterranean Sea

Abstract

During the “Cyaligure” submersible diving campaign, volcanic lavas have been sampled on a linear magnetic anomaly located off southwest Corsica. Their petrology reveals that they are metamorphic basalts, probably of tholeiitic origin. Some characteristics such as the paragenesis of the metamorphic minerals (chlorites, albite, epidote, actinolite) reveal a “greenschist” metamorphism facies. This rock would thus suggest an oceanic setting with a high thermal gradient at shallow depths. Thus, this basalt sampled in a well-defined morphostructural environment, located far from the alpine formations of Corsica, would represent the first petrological evidence of a typical oceanic crust in the Mediterranean Sea.