Eruptive history and 40Ar=39Ar 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 (106 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 2106 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 40Ar=39Ar ages and majorelement 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 0.90.510-5 and 0.250.0510-5 km3 yr-1, respectively. Period II (submarine, 2.13-1.48 Ma) has a 3-12 times higher Qe of 3.01.710-5 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.