Tectonic grabens and volcanism in the Aegean, Greece

The four active volcanic centres of the Aegean arc and another ten inactive volcanic centres, activated during Oligocene–Middle Pleistocene, following its southward migration are described with emphasis on their tectonic signature. They are all localized within tectonic grabens, resulting from the back-arc extension of the Hellenic arc throughout its Late Eocene–Present evolution. Our study was based on geological maps and the transverse tectonic profiles both onshore and offshore. The material presented is either from our own publications (usually modified) or new. The orientation of the tectonic grabens depends on the extensional stress field of each period and region. The existence of Late Miocene granitic rocks in the Cyclades without outcrops of Late Miocene volcanics is probably due to the considerable uplift of the Cycladic metamorphic core complex that has denudated the upper geological formations together with the volcanic rocks. The volcanic activity is observed within the arc parallel marine molasse of the North Aegean–Rhodope back arc basin during Oligocene–Early Miocene and within the Plio-Quaternary marine arc parallel tectonic grabens/basins of the South Aegean. Middle-Late Miocene volcanic rocks are observed within continental tectonic grabens/basins only in the lateral margins of the Cycladic metamorphic tectonic window.