episodic onset of explosive and silicic-dominated volcanism in a continental rift; insights from the Permian Oslo Rift, Norway

The nature of rifting episodes and their associated volcanism mark key stratigraphic events in the evolution of volcano-sedimentary basins. Following the final assemblage of Pangea, the European region was subject to rifting and magmatism during crustal re-equilibration throughout the Permian. The a...

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Bibliographic Details
Main Authors: Jack Whattam, Ivar Midtkandal, Dougal Jerram, Sara Callegaro, Henrik Svensen
Format: Article
Language:English
Published: Volcanica 2024-12-01
Series:Volcanica
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Online Access:https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/281
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Summary:The nature of rifting episodes and their associated volcanism mark key stratigraphic events in the evolution of volcano-sedimentary basins. Following the final assemblage of Pangea, the European region was subject to rifting and magmatism during crustal re-equilibration throughout the Permian. The aborted, partially eroded Oslo Rift is an excellent archive of this Permian magmatism, but the late-stage volcanological evolution is poorly understood. We present the first detailed documentation of a succession covering this period, with mafic lavas and volcaniclastic (tuff breccia) deposits, trachy-andesitic tuffs, and rheomorphic to moderately welded ignimbrites. Contrary to previous ideas, we show evidence suggesting the development of Strombolian-type scoria-cones, silicic fissure-fed eruptions, and major periods of rift-wide volcanic quiescence. Our observations highlight episodic silicic volcanism characterised by rapid evolution from high-grade ignimbrites to moderately and poorly welded ignimbrites. We infer rapid emptying of large, shallow silicic reservoirs and frequent source switching is responsible for the observed characteristics.
ISSN:2610-3540