The geology of the Sorjusdalen area, Nordland, Norway.

• Main Authors: Cooper, M.A., Ferriday, I.L., Halls, C., Bliss, G.M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1979
• Subjects: OMDANNING; PETROGRAFI; GEOKRONOLOGI; STRATIGRAFI; TEKTONIKK; MINERALISERING; Låmivatnet; Norway; Sulitjelma; Nordland
• Online Access: https://hdl.handle.net/11250/2675082

The rocks of the Sorjusdalen area are divided into two distinct tectono-stratigraphic sequences, the lower termed the Pieske\/Vasten Nappe and the upper the Gasak Nappe. The mutual contact of the nappes is imbricate in character and is marked by several distinctive lithologies and tectonic features. The Sulitjelma Gabbro was intruded across this contact resulting in intrusive relationships with both tectono-stratigraphic sequences. There are three phases of folding in the area, but only F1 and F2 have any significant effect on the distribution of lithologies. F1, a phase of NE-SW trending isoclinal folds with an axial planar schistose foliation, is associated with nappe emplacement. The open, E-W trending F2 folds deform the F1 fabric and appear to be on the southern limb of a major F2 synform. Medium-pressure regional metamorphism reached its peak during F1, producing a pattern of inverted isograds; the easternmost structurally lower units are greenschist facies and the westernmost structurally highest units are middle amphibolite facies. The Sulitjelma Gabbro has a thermal aureole and yet is locally profoundly affected by regional metamorphism, indicating pre- to syn-metamorphic intrusion. The emplacement of the Gasak Nappe during F1, was likewise syn-metamorphic and just prior to the intrusion of the gabbro. 35944