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SSF-Svalbard Science Forum

Timing and origin of Miocene flood volcanism on Spitsbergen: the Seidfjellet Formation revisited (RiS ID 12088)

Awarded: NOK 0.10 mill.

Mantle-derived volcanism accompanied the Cenozoic lithosphere evolution of the NE Greenland and NW Barents Sea shelves during final separation of the North American and Eurasian tectonic plates. It is unclear, however, to what extent continental breakup was influenced by deep-sourced mantle plume activity, primarily because the on- and off-shore volcanic provinces are poorly characterized in terms of magma volumes and compositions, as well as timing of magma emplacement. Remnants of Miocene basaltic lava flows occur in NW Spitsbergen (Seidfjellet Formation). Because of logistical challenges to conduct field work on top of this remote and glaciated mountain plateau, previous petrological investigations were restricted to a small number of localities with only a few samples analyzed . Nonetheless, this pioneering work established that mantle-derived magmatism occurred at ca. 10 Ma, and that both silica-saturated ‘tholeiitic’ and silica-undersaturated ‘alkaline’ magma types were produced. A more systematic and modern analytical approach to better understand the nature and origin of the Seidfjellet Formation is required. Relevant scientific questions are whether the up to 400 m thick volcanic succession formed during a short period of time, or records prolonged rift-related (passive) mantle upwelling and associated melting. Furthermore, do the alkalic and tholeiitic basalts share a common lithospheric mantle source and are related by increasing degrees of partial melting during rift evolution, or do they represent discrete melting products of a compositionally heterogeneous plume head that impinged beneath the lithosphere? To address these and several other outstanding issues, this new PhD project aims at systematically sampling the Seidfjellet Formation over its full geographic and stratigraphic extent, and to conduct a modern analytical program on the new samples. The project is thematically and logistically linked to RiS-11825 and RiS-12102.

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SSF-Svalbard Science Forum