[S-VC25] International Volcanology

[SVC25-10] Results from IODP Expedition 398: Giant offshore pumice deposit records a shallow submarine explosive eruption of ancestral Santorini

Tim Druitt¹, Steffen Kutterolf ², Thomas A. Ronge ³, Christian Hübscher ⁴, Paraskevi Nomikou⁵, Jonas Preine ⁴, Ralf Gertisser ⁶, Jens Karstens ², Jörg Keller⁷, Olga Koukousioura ⁸, Michael Manga⁹, Abigail Metcalfe¹, Molly McCanta¹⁰, *Iona McIntosh¹¹, Katharina Pank², Adam Woodhouse¹², Sarah Beethe¹³, Carole Berthod¹⁴, Shun Chiyonobu¹⁵, Hehe Chen¹⁶, Acacia Clark¹⁷, Susan DeBari¹⁸, Raymond Johnston¹⁹, Ally Peccia²⁰, Yuzuru Yamamoto²¹, Alexis Bernard²², Tatiana Fernandez Perez ²³, Christopher Jones²⁴, Kumar Batuk Joshi²⁵, Günther Kletetschka²⁶, Xiaohui Li ²⁷, Antony Morris²⁸, Paraskevi Polymenakou ²⁹, Masako Tominaga³⁰, Dimitrios Papanikolaou⁵, Kuo-Lung Wang³¹, Hao-Yang Lee³¹ (1.University Clermont-Auvergne, CNRS, IRD, OPGC, Laboratoire Magmas et Volcans, Clermont-Ferrand, France, 2.GEOMAR Helmholtz Centre for Ocean ResearchKiel, Wischhofstrasse 1-3, D-24148 Kiel, Germany, 3.International Ocean Discovery Program, Texas A&M University, College Station, TX 77845, USA, 4.Institute of Geophysics, University of Hamburg, Bundesstrasse 55, D-20146 Hamburg, Germany, 5.Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, 15784 Athens, Greece, 6.School of Geography, Geology and the Environment, Keele University, Keele, Staffordshire ST5 5BG, UK, 7.Institut für Geo- und Umweltnaturwissenschaften, Mineralogie - Petrologie, Albertstraße 23b, 79104 Freiburg, Germany, 8.School of Geology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece, 9.Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA, 10.Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN 37996-1526, USA, 11.Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka, Kanagawa 237-0061, Japan, 12.Institute for Geophysics, University of Texas, J.J. Pickle Research Campus, Bldg. 196, Austin, TX 78758, USA, 13.College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97333, USA, 14.Institut De Physique Du Globe De Paris, Centre National de la Recherche Scientifique (CNRS), 75005 Paris, France, 15.Faculty of International Resource Sciences, Akita University, Akita Prefecture, Akita 0108502, Japan, 16.School of Ocean Sciences, China University of Geosciences, Haidan District, 100083 Beijing, China, 17.School of Natural Sciences/CODES, University of Tasmania, Hobart 7005, Australia, 18.Geology Department, Western Washington University, Bellingham, WA 98225, USA, 19.School of Geosciences, University of South Florida, Tampa, FL33620, USA, 20.Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA, 21.Graduate School of Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo 657-8501, Japan, 22.Laboratoire des Fluides Complexes et leurs Réservoirs, Université de Pau et des Pays de l’Adour, F-64000 Pau, France, 23.Department of Geology, Kent State University, 221 McGilvrey Hall, 325 S Lincoln Street, Kent, OH 44242, USA, 24.Department of Earth and Planetary Sciences, University of California, Riverside, CA 92506, USA, 25.Solid Earth Research Group, National Centre for Earth Science Studies, Thiruvananthapuram, Kerala 695011, India, 26.Geophysical Institute, University of Alaska Fairbanks, 2156 Koyukuk Drive, Fairbanks, Alaska 99775, USA, 27.Key Laboratory of Submarine Geoscience and Prospecting Techniques, Ocean University of China, Qingdao, China, 28.School of Geography, Earth and Environmental Sciences, Plymouth University, Drake Circus, Plymouth PL4 8AA, UK, 29.Institute of Marine Biology, Biotechnology and Aquaculture, Hellenic Centre for Marine Research, Heraklion, Greece, 30.Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA, 31.Institute of Earth Sciences, Academia Sinica, Taipei 11529, Taiwan)

Keywords:IODP, submarine eruption, pyroclastic, turbidite

The South Aegean Volcanic Arc, which lies in the Eastern Mediterranean, has been active since about 4.7 Ma and today contains a number of active volcanic islands and submarine volcanoes. From 11 December 2022 to 10 February 2023, Expedition 398 of the International Ocean Discovery Program (IODP) conducted scientific ocean drilling in the Christiana-Santorini-Kolumbo (CSK) volcanic field in the center of the arc. This volcanic field contains the iconic Santorini volcano (a partially flooded caldera that produced the Late Bronze Age or 'Minoan' eruption in 1630 BCE) and Kolumbo volcano (an active shallow submarine volcano that erupted in 1650 CE), as well as the extinct and eroded Christiana volcano. Onland eruption deposits in the CSK volcanic field have been well studied; a key objective for Expedition 398 was therefore to recover seafloor sediments in the surrounding marine basins that may record previously unknown eruptions as well as valuable insights into eruption, transport and deposition processes of marine volcanism.

Expedition 398 recovered 3356 metres of core from 12 drill sites around the CSK field. These cores contained large quantities of volcaniclastic deposits and provide a record of eruptions going back to >1 Ma. Here we present the discovery of a giant rhyolitic pumice deposit emplaced 520 ± 10 ky ago, which we name the Archaeos Tuff (from the Greek for 'ancient'). Based on a multidisciplinary approach integrating evidence from geochemistry, grain size and textural observations, physical properties, biostratigraphy and core-seismic analysis, we interpret this deposit as evidence of a high-intensity, shallow submarine eruption of ancestral Santorini volcano. The Archaeos Tuff was emplaced in water depths of 200 to 1000 metres and formed a >89 ± 8 km³ volcaniclastic megaturbidite up to 150 metres thick in the surrounding marine basins. The identification and correlation with thin ignimbrite layers on three surrounding islands confirms that the eruption breached the sea surface. This previously unknown eruption is one of the largest identified in the South Aegean Volcanic Arc, and highlights the hazards from submarine explosive eruptions.

This study has been published as Druitt et al (2024) Communications Earth and Environment
https://doi.org/10.1038/s43247-023-01171-z