Stratigraphy of the Upper Miocene volcanic rocks of the Island of Kos, Greece : geodynamic implications

Abstract

Kos is one of several localities (Samos, Patmos, Bodrum) in the southeast Aegean Sea with Upper Miocene volcanic rocks. The stratigraphic succession of flows, ignimbrites and interbedded sediments was studied in the field in order to better understand the age, distribution, source and tectonic setting of Upper Miocene volcanic rocks of Kos. Previous radiometric dating shows that the age of the volcanism is about 10 Ma.

In northern Kos, thin andesite flows and dacite domes are overlain by thin pyroclastic rocks near Profitis Ilias and at Tripa; north of Agios Fokas, a thin pyroclastic succession includes lahars. In southern Kos, pyroclastic successions totalling 80 m in thickness are interbedded with Miocene elastic sediments and marls at Agios Fokas and Agios Stefanos.

The results on the basis of petrography and geochemistry suggest correlations between Agios Stefanos and Agios Fokas pyroclastic rocks and affinity to the minor andesite-dacite volcanism at Profitis Ilias and Tripa. Paleocurrent indicators in ignimbrites suggest that the Agios Stefanos section was derived from a source to the southeast and Agios Fokas from a source to the south, most probably from a Miocene precursor of the modern volcanic centre of Yali-Nisyros.