Title: Volcanic structures and magmatic evolution of the Vesteris Seamount, Greenland Basin

Katharina Anna Unger Moreno1,5, Janis Thal1, Wolfgang Bach1,2, Christoph Beier3, Karsten Matthias Haase4

1Fachbereich Geowissenschaften, Universität Bremen, Klagenfurter Str. 2, D-28359 Bremen, Germany; 2MARUM Center for Marine Environmental Sciences, Universität Bremen, Leobener Str., D-28359 Bremen, Germany; 3Department of Geosciences and Geography, Research Programme of Geology and Geophysics (GeoHel), University of Helsinki, FIN-00014 Helsinki, Finland; 4GeoZentrum Nordbayern, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 5, D-91054 Erlangen, Germany; 5GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstr. 1-3, 24148 Kiel, Germany

Event: GeoKarlsruhe 2021

Date: 2021

DOI: 10.48380/dggv-vwzc-ar06

The solitary intraplate volcano Vesteris Seamount is located in the Central Greenland Basin and rises around 3000 m above the seafloor with a total eruptive volume of ~500 km3. Newly acquired high-resolution bathymetry allows through backscatter data and raster terrain analysis to distinguish several volcanic structures. The Vesteris Seamount is a northeast to southwest elongated stellar-shaped seamount with an elongated, narrow summit radially surrounded by irregular volcanic ridges, separated by volcanic debris fans. Whole rock geochemical data of 78 lava samples form tight liquid lines of descent with MgO concentrations ranging from 12.6 to 0.1 wt. %, implying that all lavas evolved from a similar parental magma composition. Video footage from ROV dives show abundant pyroclastic deposits on the summit and on the flanks whereas lavas are restricted to flank cones and dike intrusions. The seamount likely forms above a crustal weak zone and the local volcanic stress field increasingly affects the constructive and destructive features on the surface. The evolution of Vesteris Seamount reflects the transition from deep, regional crustal stresses in the older features to local, volcanic stresses in the younger structural features. The Vesteris Seamount enables to understand the structural and magmatic evolution of intraplate volcanoes distant from plate boundaries by combining detailed geological sampling, high-resolution bathymetry and underwater video coverage.

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