Polyphase Caledonian metamorphism in the Precambrian basement of Rogaland/Vest-Agder, SW Norway.

Abstract

In the Sveconorwegian basement of Rogaland\/Vest-Agder, SW Norway, two incipient Caledonian metamorphic overprints are assumed on the basis of petrological textures and regional extension of the metamorphic mineral distributions. The inferred M4a is a burial metamorphism mainly in prehnite-pumpellyite facies and the M4b a metamorphism mainly in greenschist facies, restricted to the vicinity of the Caledonides. In order to propose a model sequence of retrograde metamorphic events in the basement of the whole of South Norway the available mineral records of newly formed green biotite, stilpnomelane, prehnite and pumpellyite are integrated with relevant age determinations and other geological information.