HYDROTHERMAL SEDIMENTATION IN THE CALDERA OF SANTORINI, HELLENIC VOLCANIC ARC

Sediments in the caldera of Santorini are receiving a hydrothermal inp ut of iron and manganese from presently active hydrothermal vents off the Kameni Islands, and are enriched in these elements in their surfac e layer. However, greater Fe-Mn enrichments occur in discrete layers a t depth in the cores separated from the surface by Fe-Mn poor sediment s, suggesting that a past hydrothermal event may have been more intens e than the present one. The buried Fe-Mn enriched layers occur above a turbidite thought to have resulted from sediment slumping due to a ma jor volcanic eruption and earthquake in 1650, and are thought to have formed consequent on the activation of faults related to the magma cha mber by the eruption facilitating seawater-rock interaction processes and the formation of metal-rich hydrothermal solutions.