The effects of penetrative Sveconorwegian deformations on RbSr isotope systems in the Römskog-Aurskog-Höland Area, SE Norway

Paleostress field reconstruction in the Oslo region

“…The Precambrian basement surrounding the Oslo Graben area formed between 1800 Ma and 1550 Ma and was metamorphosed during the Sveconorwegian orogeny between 1100 Ma and 950 Ma (Berthelsen, 1980(Berthelsen, , 1992Skjernaa and Pedersen, 1982). During early Paleozoic times the area was part of an extensive shelf, where Cambro-Silurian marine sediments and Silurian to Devonian red Fig.…”

Timing of Gothian structural evolution in SE Norway: A Rb-Sr whole-rock age study

“…Although the correlation of the incorporated areas is still 13.0 13.0 9.5 11.0 8.0 11.0 8.5 7.5 5.0 under debate, the radiometric ages published in Hageskov & Pedersen (1981, 1988, Skjernaa & Pedersen (1982) and the present paper have enabled a compilation of the orogenic evolution incorporating both tectonic segments across the Ørje mylonite zone (Dalsland Boundary Thrust). The early orogenic evolution in SE Norway can be ascribed to the Gothian orogeny within the 1.75-1.55 Ga interval reviewed by Gaál & Gorbatschev (1987).…”

“…Previous Rb-Sr wholerock dating of rocks from the Østfold and Romerike Complexes yielded ages ranging from 1.7 Ga to 0.9 Ga, spanning the post-Svecofennian development during the Gothian and Sveconorwegian Orogens. The tectonic development and the orogenic evolution have been described by Pedersen et al (1978), Berthelsen (1980Berthelsen ( , 1987, Hageskov (1980), Hageskov & Pedersen (1981, 1988, Skjernaa & Pedersen (1982), Graversen (1984) and Skjernaa (1997).…”

“…1.56-1.58 Ga) sets the lower limit to the Gothian orogeny. The F 2 and F 3 fold episodes are separated by the intrusion of the Pedersen et al (1978); 2) Hageskov & Pedersen (1981, 1988; 3) Graversen 1984; 4) Skjernaa & Pedersen (1982) anorogenic Moss-Filtvet complex at 1.32 6 0.02 Ga (Hageskov & Pedersen 1981). The resetting age of the augen gneiss at 1.06 6 0.17 Ga may thus be related to the F 3 deformation during the Sveconorwegian orogeny.…”

“…Although resetting may have invalidated some results, the integrated approach helps to model the timing of regional folding phases during the Gothian orogeny. Together with data from Hageskov & Pedersen (1981, 1988 and Skjernaa & Pedersen (1982), a correlation between the orogenic evolution in the Østfold and Median segments in SE Norway is proposed (see Table 5). …”