The nature of the acoustic basement on Mendeleev and northwestern Alpha ridges, Arctic Ocean

► Seismic reflection/refraction data from the Mendeleev/Alpha ridges are investigated. ► Basement geology are interpreted to be basalt flows capping voluminous tuff deposits. ► Two volcanic centres are identified. ► The upper volcanic carapace was emplaced during a brief igneous episode. ► The upper volcanic is most likely part of Late Cretaceous circum Arctic volcanism.