A distinct source and differentiation history for Kolumbo submarine volcano, Santorini volcanic field, Aegean arc

Abstract

This study reports the first detailed geochemical characterization of Kolumbo submarine volcano in order to investigate the role of source heterogeneity in controlling geochemical variability within the Santorini volcanic field in the central Aegean arc. Kolumbo, situated 15 km to the northeast of Santorini, last erupted in 1650 AD and is thus closely associated with the Santorini volcanic system in space and time. Samples taken by remotely‐operated vehicle that were analyzed for major element, trace element and Sr‐Nd‐Hf‐Pb isotope composition include the 1650 AD and underlying K2 rhyolitic, enclave‐bearing pumices that are nearly identical in composition (73 wt.% SiO2, 4.2 wt.% K2O). Lava bodies exposed in the crater and enclaves are basalts to andesites (52–60 wt.% SiO2). Biotite and amphibole are common phenocryst phases, in contrast with the typically anhydrous mineral assemblages of Santorini. The strong geochemical signature of amphibole fractionation and the assimilation of lower crustal basement in the petrogenesis of the Kolumbo magmas indicates that Kolumbo and Santorini underwent different crustal differentiation histories and that their crustal magmatic systems are unrelated. Moreover, the Kolumbo samples are derived from a distinct, more enriched mantle source that is characterized by high Nb/Yb (>3) and low 206Pb/204Pb (<18.82) that has not been recognized in the Santorini volcanic products. The strong dissimilarity in both petrogenesis and inferred mantle sources between Kolumbo and Santorini suggests that pronounced source variations can be manifested in arc magmas that are closely associated in space and time within a single volcanic field.

Fluid Geochemistry Contribution to the Interpretation of the 2011–2012 Unrest of Santorini, Greece, in the Frame of the Dynamics of the Aegean Volcanic Arc

“…Klaver et al (), based on a complete analysis of minero‐petrographic and radiogenic features of Santorini and Kolumbo volcanic deposits, infer that these two volcanic centers have no shallow connection between their plumbing systems as they tap unrelated and distinct mantle sources, the one beneath Santorini showing more contamination by fluid‐rich sediments.…”

Evidence for a Moist to Wet Source Transition Throughout the Oman‐UAE Ophiolite, and Implications for the Geodynamic History

“…Middle REE (MREE) fractionation is a characteristic of amphibole involvement in the genesis of a magma (Davidson et al, ; Klaver, Carey, et al, ). Amphibole preferentially incorporates MREEs over heavy REEs, resulting in a decrease in Dy/Yb with increasing amphibole fractionation (Davidson et al, ; Macpherson et al, ).…”

“…Showing the relative low amounts of Y in Phase 2 magmatism compared to Phase 1, indicative of the influence of amphibole (Davidson et al, ; Klaver, Carey, et al, ). Fractional crystallization vectors from Klaver, Carey, et al (). (c) Dy/Dy* versus Dy/Yb following the methodology of Davidson et al ().…”

New insights into the plumbing system of Santorini using helium and carbon isotopes

“…The Kolumbo line extends to the NE to the Kolumbo submarine volcano, which is the largest of 25 submarine volcanic cones sited along this fault and is located ~7 km of Santorini (Nomikou et al, 2012). Trace elements and radiogenic isotopes have shown significant differences suggesting a different petrogenesis and a different mantle source between those two volcanoes (Klaver et al, 2016), although, based on helium isotopes, Rizzo et al (2016) suggest that the two volcanoes share the same mantle source but a different plumbing.…”