Reappraising the P-T evolution of the Rogaland-Vest Agder Sector, southwestern Norway
MetadataShow full item record
© 2016 China University of Geosciences (Beijing) and Peking University.The Rogaland-Vest Agder Sector of southwestern Norway comprises high-grade metamorphic rocks intruded by voluminous plutonic bodies that include the ~1000 km2 Rogaland Igneous Complex (RIC). New petrographic observations and thermodynamic phase equilibria modelling of three metapelitic samples collected at various distances (30 km, 10 km and ~10 m) from one of the main bodies of RIC anorthosite were undertaken to assess two alternative P-T-t models for the metamorphic evolution of the area. The results are consistent with a revised two-phase evolution. Regional metamorphism followed a clockwise P-T path reaching peak conditions of ~850-950 °C and ~7-8 kbar at ~1035 Ma followed by high-temperature decompression to ~5 kbar at ~950 Ma, and resulted in extensive anatexis and melt loss to produce highly residual rocks. Subsequent emplacement of the RIC at ~930 Ma caused regional-scale contact metamorphism that affected country rocks 10 km or more from their contact with the anorthosite. This thermal overprint is expressed in the sample proximal to the anorthosite by replacement of sillimanite by coarse intergrowths of cordierite plus spinel and growth of a second generation of garnet, and in the intermediate (10 km) sample by replacement of sapphirine by coarse intergrowths of cordierite, spinel and biotite. The formation of late biotite in the intermediate sample may suggest the rocks retained small quantities of melt produced by regional metamorphism and remained at temperatures above the solidus for up to 100 Ma. Our results are more consistent with an accretionary rather than a collisional model for the Sveconorwegian Orogen.
Showing items related by title, author, creator and subject.
Kirkland, Chris; Slagstad, T.; Johnson, Tim (2018)© 2018 International Association for Gondwana Research. During metamorphism, inherited or detrital zircon grains commonly serve as a template onto which new generations of metamorphic zircon precipitates, charting successive ...
Early Paleozoic metamorphic rocks of the Erguna block in the Great Xing'an Range, NE China: Evidence for the timing of magmatic and metamorphic events and their tectonic implicationsZhou, Jian-bo; Wilde, Simon; Zhang, X.; Ren, S.; Zheng, C. (2011)The Erguna block is a crustal unit located along the eastern margin of the Central Asian Orogenic Belt (CAOB) in the far north of China. It contains a variety of khondalitic rocks that include sillimanite- and garnet-bearing ...
Closed system behaviour of argon in osumilite records protracted high-T metamorphism within the Rogaland–Vest Agder Sector, NorwayBlereau, Eleanor; Clark, Chris ; Jourdan, Fred ; Johnson, Tim ; Taylor, Richard ; Kinny, Pete ; Danišík, Martin ; Hand, M.; Eroglu, Ela (2019)© 2019 John Wiley & Sons Ltd Here, we present results of the first 40Ar/39Ar dating of osumilite, a high-T mineral that occurs in some volcanic and high-grade metamorphic rocks. The metamorphic osumilite studied ...