Metamorphic petrology of the Froland corundum-bearing rocks: the cooling and uplift history of the Bamble Sector, South Norway

Abstract

Corundum-bearing rocks from Kleggåsen, Froland, preserve metamorphic textures which reflect the cooling and uplift path of the Bamble Sector. The P-T path may be correlated with a T-t path constructed from published ages. The P-T path starts at the thermal climax of prograde metamorphism, M 1 (c.750\u00B0C 7 kb), characterized by Sil,Pl, Bt, Rt and Crn. Subsequent near-isobaric cooling res- ults in M ll, charactreized by Ky + Ms +- Chl veinlets (600-700\u00B0C, 7kb). This marks the onset of rehydration. M lll assemblages of Mrg +- Crn formed around 500-570\u00B0C and 3-7 Kb, and are followed by M IV (c. 400\u00B0C, 2-4 kb) character- ized by Ms, Bt and Ep. The trajectory from M II via M III to M IV is believed to reflect the uplift of the area in response to Sveconorvegian upthrusting.