6533b839fe1ef96bd12a6e2f

RESEARCH PRODUCT

Pliocene tourmaline rhyolite dykes from Ikaria Island in the Aegean back-arc region: geodynamic implications

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Very rare rhyolite dykes cross-cutting a Miocene I-type biotite-granite were discovered on Ikaria Island in the Aegean back-arc region. Their intrusion postdates exhumation of the granite to brittle crust at about 6.0-3.6 Ma; hence a Pliocene age is inferred. Petrological, geochemical and isotopic arguments indicate an origin through melting of crustal lithologies (tourmaline greywackes/semipelites) with no detectable contribution from asthenospheric sources. Strontium isotope ratios are relatively low unlike values for sediments entering the Hellenic trench but similar to those for certain Miocene Cycladic I-type granites and low-Rb Permo-Carboniferous Cycladic basement acid orthogneisses. Crust-mantle Sr-Nd isotopic mixing modelling also requires a low-Sr crustal end-member. The presence of Pliocene rhyolitic volcanism in the Aegean back-arc region in places distant from any possible subduction zone influence is attributed to slab tear at the eastern end of the Hellenic trench and attendant entrance and...