Spectral study of hydrothermally altered volcanic deposits of the Greek island Milos as a Martian analog

Abstract

For the study of the aqueous history of Mars, the knowledge of mineral characteristics for specific geologic environments is essential [1]. Previous studies of regions on Earth suitable as analogs for studying geological processes on planetary surfaces, such as the Italian island Vulcano [2] already enabled the identification of secondary sulfate minerals formed by acid alteration of volcanic deposits due to fumarolic activity. In this work, we extend this study with the spectral investigation of alteration minerals measured on the volcanic island Milos (Greece) during fieldwork performed in 2024.

Milos is a volcanic island in the Aegean Sea and a part of the subduction-related South Aegean Volcanic Arc [3]. Hydrothermal activity changed the initial composition of the rocks and led to the formation of various secondary minerals - making the island an ideal location to extend our spectral library, coupled with geologic context information. Spectral measurements presented here were performed with a portable VIS-NIR spectrometer operating at wavelengths between 0.35 and 2.5 µm in two locations on the island: 1) a persistently active fumarolic field in the area of Kalamos Dome (Fig. 1 a + b) and 2) an abandoned sulfur mine at Paliorema (Fig. 1 c + d), where sulfur was mainly extracted from underground deposits.