Abstract
Three principal episodes (at c. 1300, 1250 and 1170 Ma.) of faulting and associated alkaline magmatism are recognised in the evolution of the Gardar province in south Greenland.
Terrestrial sediments and lavas, accumulated in fault-bounded troughs and cut by Early Gardar alkaline complexes, constitute evidence for continental rifting and concomitant volcanism in the first episode. Subsequent (c. 1250 Ma.) basic dykes, followed by faulting and intrusion of alkaline central complexes are related to a Mid-Gardar episode of continental rifting.
The Late Gardar episode involved intrusion of ENE and NE trending dyke swarms with further faulting and emplacement of alkaline complexes, within a zone c. 70 km broad. One major subzone (Tugtutôq — Narssaq) characterised by massive ‘giant dykes’, followed by smaller dykes and cross-cutting central complexes, is centred upon a closed gravity ‘high’, c. 80 km long by 25 km broad. This anomaly is attributed to an underlying mass of high density rocks at shallow depth.
Evidence from the Gardar province suggests that continental rifting was recurrent over more than 100 Ma. and that the magmatic history was controlled by the structure and character of the underlying lithosphere.
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© 1978 D. Reidel Publishing Company, Dordrecht, Holland
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Upton, B.G.J., Blundell, D.J. (1978). The Gardar Igneous Province: Evidence for Proterozoic Continental Rifting. In: Neumann, ER., Ramberg, I.B. (eds) Petrology and Geochemistry of Continental Rifts. NATO Advanced Study Institutes Series, vol 36. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-9803-2_14
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