Abstract
The calc-alkaline lavas of the submarine Pausanias Volcanic Field and the neighboring Methana peninsula represent the largest volcanic edifices of the western South Aegean Volcanic Arc(SAVA)in the Mediterranean Sea and erupted on 30-35 km thick continental crust.We report the first whole rock major and trace elements together with Sr-Nd-Pb isotope ratios for basaltic to andesitic lavas from the submarine Pausanias Volcanic Field consisting of six smaller,volcanic structures.The mafic lavas have the most primitive compositions of the SAVA with MgO of up to 9 wt% and Ni concentrations >100 ppm.The incompatible trace element abundance patterns of the Pausanias and Methana lavas overlap and have typical island arc patterns,but Pausanias lavas display a larger geochemical heterogeneity on a smaller spatial scale compared to those from Methana.The Pausanias lavas resemble those from Methana in Sr,Nd,and Pb isotopes reflecting higher sediment subduction in the western SAVA than in the central arc at Santorini.The variability of incompatible element concentrations at relatively constant isotope compositions suggests variable degrees of partial melting of a peridotite-sediment melange diapir in the mantle wedge.The Pausanias magmas formed from a less depleted mantle source compared to the central SAVA and their ascent in an extensional basin supported relatively rapid ascent without the extensive stagnation in the crust observed in the Methana magmas.The compositional differences between Pausanias and Methana imply differences in their composition and/or transport in the mantle wedge and the crust,allowing highly variable melts to reach the surface within a spatial distance of few kilometers.
NSTL