High-resolution geochronology applied to the Milos volcanic field (Greece), combined with a geochemical study

Milos is an island located in the southwestern part of the Aegean Sea (Greece) and is mainly build-up of volcanic rocks. During its three million years of volcanic history at least twenty-one eruptions occurred, first below and later above sea level. The low eruption frequency of Milos makes it a perfect natural laboratory for studying volcanic eruption frequency, which is crucial for understanding volcanic hazards. Precise and accurate dating of the single eruptions is important to reconstruct the volcanic history, which was very difficult until recently for such young, and sometimes partially altered samples. To obtain a high-resolution geochronological framework for the Milos volcanic field, I combined three analytical methods (40Ar/39Ar dating, geochemistry and diffusion modelling on minerals) with numerical modelling. There are four different periods of the Milos volcanic field with different eruption frequencies varying from 1 per 70.000 to 1 per 440.000 years. The volcanoes on Milos can be dormant for more than half a million years if there is no or a small magma flux from deeper levels. On the other hand, a larger flux of magma from deeper levels can result in eruptions that are only separated within months of each other. Tectonic activity in the crust beneath Milos appears to be a factor that controls the degree of magmatic activity.