02 May 2023
 | 02 May 2023
Status: this preprint is currently under review for the journal GChron.

Volcanism straddling the Mio-Pliocene boundary on Patmos (East Aegean Sea): Insights from new 40Ar/39Ar ages

Katharina M. Boehm, Klaudia F. Kuiper, Bora Uzel, Pieter Z. Vroon, and Jan R. Wijbrans

Abstract. The island of Patmos, in the eastern Aegean Sea, consists almost entirely of late Miocene to Pliocene volcanic rocks. The magmatism in the Aegean is governed by subduction of the African plate below the Eurasian plate, back-arc extension, slab roll-back, slab edge processes and westward extrusion of central Anatolia to the west along the Northern Anatolian Fault into the Aegean domain, The evolution of the Aegean basin is that of a back arc setting, with a southerly trend in the locus of both convergent tectonics, and back arc stretching, allowing intermittent upwelling of arc, lithospheric and asthenospheric magmas.

Here, we present new 40Ar/39Ar age data for Patmos and the nearby small island of Chilomodi to place this volcanism in a new high resolution geochronological framework. High resolution geochronology provides a key to understanding the mechanisms of both the tectonic and magmatic processes that cause the extrusion of magma locally, and sheds light on the tectonic evolution of the larger region of the back-arc basin as a whole.

The volcanic series on Patmos is alkalic, consistent with a back arc extensional setting and ranges from trachybasalt, to phonolites, trachytes and rhyolites, with SiO2 ranging from 51.6–80.5 wt.% and K2O from 2–11.8 wt.% with extrusion ages ranging from 6.59 ± 0.14 Ma–5.17 ± 0.11 Ma. Volcanism on Patmos and adjacent Chilomodi can be understood by a combination of mantle and crustal tectonic processes including influence of transform faults and rotational crustal forces that also caused the opening of the south Aegean basin due to roll back of the subducting slab south of Crete.

Katharina M. Boehm et al.

Status: open (until 21 Jun 2023)

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  • RC1: 'Comment on gchron-2023-11', Uwe Ring, 03 Jun 2023 reply

Katharina M. Boehm et al.

Katharina M. Boehm et al.


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Short summary
The island of Patmos is situated in the Southern Aegean Sea (Greece), just north of the present locus of active volcanism. The island is almost entirely build of volcanic rocks, which are 6.6 to 5.2 million years old. We obtain these ages with 40Ar/39Ar dating technique on sanidine and biotite minerals. Our new age data indicates a geologically brief volcanic period (lasting less than 1.5 million years) which can be divided in three distinct volcanic intervals and can be correlated to tectonics.