Eruptive history and <sup>40</sup>Ar∕<sup>39</sup>Ar geochronology of the Milos volcanic field, Greece

Abstract

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 2 × 106 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 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.

Petrological and geochemical evidence for a hot crystallization path and a recharge filtering bypass at Antimilos, Milos volcanic field, Greece

“…These cumulates are thought to highlight the importance of amp in the production of silicic liquids via peritectic reactions (Blatter et al 2017;Klaver et al 2018) in deep crustal hot zones (Annen et al 2006). A similar process has been proposed for magmas erupted on Milos (Zhou 2021;unpublished PhD Thesis) where modal amphibole is a significant component of the erupted products. In experimental studies of basaltic magmas from the Aegean arc, ferro-tschermakite to pargasitic hornblende compositions are stable up to 975 °C and H 2 O melt ≥ 3.5 wt% at fO 2 ∼ NNO (Andujar et al 2015).…”

“…a Total Alkali-Silica diagram (Le Bas et al 1986) for classification of Antimilos whole rock samples and groundmass glasses of rhyolite schlieren (EPMA data) b-e Harker diagrams of selected major elements against SiO 2 . Previous data from Antimilos (Sonder 1924;Marinos 1961;Fytikas et al 1986;) and Milos (Barton et al 1983;Fytikas et al 1986;Zhou et al 2021) are plotted for comparison. Melts potentially in equilibrium with enclave and felsic clot plagioclase calculated with the method outlined in Scruggs and Putirka (2018) are also shown in e. Candidate liquid lines of decent for different fractional crystallization and assimilation plus fractional crystallization scenarios calculated with alphaMELTS are plotted for comparison with the whole rock trends.…”

“…This study focuses on the island of Antimilos (Fig. 1a, b), located on the NW flank of the ~ 3 Ma to present Milos Volcanic Field (MVF) (Fytikas et al 1986;Francalanci et al 2007;Zhou et al 2021). By combining bulk rock geochemistry and a detailed analysis of texture and mineralogy of erupted units, we show that the Antimilos andesite-dacite suite records a hot evolutionary path.…”

Sources, transport, and deposition of metal(loid)s recorded by sulfide and rock geochemistry: constraints from a vertical profile through the epithermal Profitis Ilias Au prospect, Milos Island, Greece

“…Similarly to Profitis Ilias, the leached zone in such environments is characterized by silver halides and native Au, while the enriched zone exhibits coarse grains or nuggets of native Au and electrum (Milési et al 1999;Guilbert and Park 2007;Páez et al 2016;Arfè et al 2016). The extensive supergene mineralization at Profitis Ilias requires tectonic uplift of several hundred meters to subaerial levels, in accordance with the volcano-tectonic evolution of the island (Stewart and McPhie 2006;Zhou et al 2021). The maximum bulk rock Au concentrations are recorded at 610 to 640 m elevation (this study; Kilias et al 2001) suggesting that the water table was located around that level during the supergene stage (Fig.…”

“…The metamorphic basement is dominated by Mesozoic greenschist-to blueschist-facies metasediments of the Cycladic Blueschist Unit (Liakopoulos et al 1991;Grasemann et al 2018). The volcanism shows a general evolution from submarine pyroclastic activity (3.3 to 2.13 Ma) and submarine eruption of andesitic to rhyolitic lavas (2.13 to 1.48 Ma) to subaerial rhyolitic activity (1.48 Ma to present) (Stewart and McPhie 2006;Zhou et al 2021). Hydrothermal activity led to the formation of several hybrid epithermal-VMS-style Pb-Zn-Cu-Ag-Au vein mineralization across western Milos (Naden et al 2005;Alfieris et al 2013;Schaarschmidt et al 2021a).…”