Several small volcanic centers of Pleistocene age occur in the Woodfjorden area of NW Spitsbergen and are collectively known as the mantle-sourced Bockfjorden Volcanic Complex (BVC). The main magma type identified is basanite, an alkali basaltic variety that is typically associated with active continental rifting. However, northwestern Svalbard presents a passive continental margin to the North Atlantic and Arctic oceans since Neogene times, a tectonic environment that is expected to be either amagmatic or, when impacted by mantle plume activity, can host voluminous flood basalt volcanism. The unusual setting and composition of the BVC have puzzled petrologists for decades, and although a broad understanding of this volcanism has been developed, crucial information pertaining to its origin is still missing.
During this MSc project, it is aimed to collect new basaltic lava samples and peridotitic mantle xenoliths from the main eruptive centers for a petrological–geochemical study to further constrain the source and evolution of Pleistocene volcanic activity in NW Spitsbergen. Modern Al-in-olivine thermometry and Ca-in-olivine barometry will be applied to a large suite of spinel peridotite xenoliths to define a regional lithospheric mantle geotherm, which can be used to define the lithosphere–asthenosphere boundary. The MAGLAB algorithm will be applied to the major element compositions of near-primary magmas with the goal to independently estimate depths of melt segregation in the upper mantle and to correlate the zone of melting with deep magnetotelluric surveys in the greater North Atlantic region. Trace element and Sr-Nd-Hf isotopic compositions of the most primitive magmas will be used to address the long-term evolution of the upper mantle beneath the rather unconventional passive continental margin setting, as exposed in NW Svalbard.
The project is thematically and logistically linked to RiS-11825 and RiS-12088, and it is part of a group effort by UiT and UNIS.