Eruptive history and 40 Ar∕ 39 Ar geochronology of the Milos volcanic field, Greece

Abstract. High-resolution geochronology is essential for determining the growth rate of volcanoes, which is one of the key factors for establishing the periodicity of volcanic eruptions. However, there are less high-resolution eruptive histories ( >  10 6  years) determined for long-lived submarine arc volcanic complexes than for subaerial complexes, since submarine volcanoes are far more difficult to observe than subaerial ones. In this study, high-resolution geochronology and major-element data are presented for the Milos volcanic field (VF) in the South Aegean Volcanic Arc, Greece. The Milos VF has been active for over 3  Myr , and the first 2  ×  10 6  years of its eruptive history occurred in a submarine setting that has been emerged above sea level. The long submarine volcanic history of the Milos VF makes it an excellent natural laboratory to study the growth rate of a long-lived submarine arc volcanic complex. This study reports 21 new high-precision 40 Ar / 39 Ar ages and major-element compositions for 11 volcanic units of the Milos VF. This allows us to divide the Milos volcanic history into at least three periods of different long-term volumetric volcanic output rate ( Qe ). Periods I (submarine, ∼  3.3–2.13  Ma ) and III (subaerial, 1.48  Ma –present) have a low Qe of 0.9  ±  0.5  ×  10 −5 and 0.25  ±  0.05  ×  10 −5 km3 yr−1 , respectively. Period II (submarine, 2.13–1.48  Ma ) has a 3–12 times higher Qe of 3.0  ±  1.7  ×  10 −5 km3 yr−1 . The Qe of the Milos VF is 2–3 orders of magnitude lower than the average for rhyolitic systems and continental arcs.