124 D21. Recent Advances in Sedimentology and Stratigraphy

Monday, 23 September 2024
1:30 PM - 5:30 PM
207B

EVIDENCE FOR A BYZANTINE-ERA HYDROTHERMAL EVENT IN SANTORINI’S CALDERA FROM Hg IN IODP EXPEDITION 398 SEDIMENTS

Paper number: 124-13
Program: Technical Sessions
Time: 4:20 PM – 4:35 PM

Authors

Abstract

Santorini is a mature volcanic system located in the South Aegean volcanic arc. Its history of large explosive eruptions, which culminated in a caldera-forming eruption 3600 years ago, has been well studied. However, the post-caldera evolution of the volcanic and hydrothermal systems remains poorly understood. Our objective is to better understand of the relationship between volcanic eruptions and the activity of hydrothermal fields within the caldera, by analysing intra-caldera sediments.

This study focuses on the lithological and chemical analysis of samples from seafloor sediment cores collected from the Santorini caldera during International Ocean Discovery Program (IODP) Expedition 398 in 2023. Samples from six holes, which penetrated between depths 45 and 130 mbsf, were selected to obtain a comprehensive record of volcanic and sedimentary activity since the last caldera forming eruption in the Late Bronze Age ca.1650 BCE. The sediment record is hypothesized to include both subaerial and submarine eruptive products from the young edifice that has progressively grown within the caldera over the past 3600 years, now forming the Kameni islands.

The main aim of our study is to determine if we can detect past episodes of heightened hydrothermal activity within Santorini’s flooded caldera by examining trace metal enrichment patterns in the accumulating sediments. Our hypothesis is that sedimentary units show enrichments in elements that are typically elevated in hydrothermal fluids, indicating periods of heightened hydrothermal activity at Santorini. We will present preliminary results for down-core concentrations of elements that are strongly enriched in hydrothermal fluids, in particular mercury (Hg). We have identified a key horizon between 55 and 60 mbsf where Hg concentrations are particularly elevated, and where we have other lines of evidence that are consistent with a period of strong hydrothermal activity prior to 726 CE. We draw comparisons with the present-day hydrothermal fields on the caldera floor, and explore ways that we may constrain the extent and significance of this ancient hydrothermal event.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-401835

© Copyright 2024 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.