Extension of Trollheimen tectono-stratigraphic sequence in deep synclines near Molde and Brattvåg, Western Gneiss Region, southern Norway
pp. 181-198

A 70 km-long belt along Moldefjord contains a well-defined sequence of Caledonide thrust nappes infolded into Baltica basement, corresponding exactly to the sequence in the Surnadal syncline and Trollheimen, from base to top, the Risberget, Sætra, Blåhø-Surna, and Støren Nappes. Quartzites in areas of basement rna y correspond to Åmotsdal Quartzite tectonically sandwiched with basement in Trollheimen. The metamorphic discontinuity, previously described in the Surnadal area, between high amphibolite facies Surna Nappe and low amphibolite facies Støren Nappe, persists through the area, and newly discovered zoisite-phengite eclogite boudins in the Sætra Nappe and locally in the Risberget suggest discontinuities at lower levels. All levels are pervaded by subhorizontal lineation parallel to fold axes. Lineation is related to sinistral shear features including porphyroclast tails, S-C fabrics, shear bands, tilted boudins, mylonite, ultramylonite, and sheath and tubular folds superimposed on earlier structural features and indicating a phase of late Scandian sinistral shear under low amphibolite conditions parallel to the length of the orogen.

Peter Robinson, Department of Geology and Geography, Box 35820, University of Massachusetts, Amherst, MA 01003-5820, U.S.A.