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Explosive or effusive volcanism at the northern Reykjanes Ridge: the role of magma chemistry

Froukje M. van der Zwan 1, Dominik Pałgan2, Evelyn R. Garcia-Paredes1, Viktoria Stizek3, Mikolaj Prejc2, David Odinsson4, Jan Oliver Eisermann5, Linus Budke6, Jonas Preine6, Christian Hübscher6, Nico Augustin7

  • Affiliations: 1King Abdullah University of Science and Technology (KAUST), Saudi Arabia 2University of Gdansk, Poland 3University of Bonn, Germany 4Marine and Freshwater Research Institute, Hafnarfjörður, Iceland 5Christian-Albrechts-University of Kiel, Germany 6University of Hamburg, Germany 7Helmholtz Centre for Ocean Research Kiel, Germany

  • Presentation type: Talk

  • Presentation time: Tuesday 10:45 - 11:00, Room R290

  • Programme No: 3.16.5

  • Theme 3 > Session 16

Abstract

While mafic submarine eruptions are a main contributor to Earths volcanism, they typically pose a low hazard, due to their limited explosivity at higher depths (1). At shallower depths close to coastal communities, however, explosive eruptions can be a significant threat, but submarine eruptions are rarely observed and therefore understudied. The eruption of Surtsey, south of Iceland, in 1963 is the type-example of a shallow, mafic, submarine explosive phreatomagmatic eruption (2). Also, on the close-by northern Reykjanes Ridge, where the Mid-Atlantic Ridge rises to depths of <200 m towards Iceland, historic explosive eruptions have been reported, e.g. at Nýey in 1783 (3). However, effusive volcanism, in the form of pillow lavas, alternates with these explosive phases and remains the most abundant type of eruptions there (4). During expedition M201 in June 2024, we collected video footage and rock samples from the explosive eruption at Nýey and from an effusive eruption 10 km further south, to evaluate if the products, which displayed different eruptive behaviors, differ in their chemical composition. Here, we will present petrography and the major and trace element data of whole rocks and glasses of these samples, with particular emphasis on elements that can serve as proxy for volatiles, to evaluate the role of the magma chemistry on the explosivity of volcanoes at the Reykjanes Ridge. (1) White et al., 2003, Geoph Monograph (2) Thorarinsson, 1968, Surtsey Res Prog Rep (3) Höskuldsson et al., 2007, J Geodyn (4) Le Saout et al., 2023, Geochem Geophys Geosyst