Late Precambrian sedimentary rocks in East Finnmark, north Norway and their relationship to the Trollf jord-Komagelv fault

Abstract

The late Precambrian sedimentary rocks of the Varanger Peninsula, north Norway, occur in the Tanafjord–Varangerfjord (autochthonous) and Barents Sea (allochthonous) regions. The autochthonous region includes 4-5 km of shallow water clastic sediments with subordinate carbonates and also tillites, of late Precambrian (Upper Riphean) to Tremadocian age. The allochthonous region includes about 14 km of deep and shallow water clastic sediments with subordinate carbonates, all of Precambrian age. On Varanger Peninsula these two regions are always separated by a major strike-slip tectonic disturbance, the Trollfjord–Komagelv fault. This is a single, high-angle fault in Inner Varanger Peninsula, but in the Trollfjordalen–Lille Molvik area a braided fault pattern occurs in which an early trace of the Trollfjord-Komagelv fault has been later folded and faulted. Some structural observations support strike-slip movement along the Trollfjord-Komagelv fault, while comparison with recent strike-slip fault zones suggests that the folded fault in the Trollf jordalen-Lille Molvik area represents an inactive, curved fault trace which was abandoned and subsequently tightened by (? Caledonian) folding. Stratigraphic and structural data support recent geochronological and palaeomagnetic results which suggest the geological separation of the two regions during their deposition and perhaps during their principal deformations.

The origin of upper Precambrian diamictites, northern Norway: a case study applicable to diamictites in general

“…Dolostone beds are present both below and between diamictites in the area (Siedlecka & Roberts, 1992;Rice et al, 2011Rice et al, , 2012, and these commonly indicate a warm climate (Schermerhorn, 1974;Johnson et al, 1978;Zenger et al, 1980;Schermerhorn, 1983;McKenzie, 1991;Young, 1991). These dolostone beds have either not been discussed in a palaeoclimatological context, are believed to have formed in a cold environment, or are thought to result from climatological and chemical catastrophic turnovers on a worldwide scale (Shields, 2005).…”

Circular moraine features on the Varanger Peninsula, northern Norway, and their possible relation to polythermal ice sheet coverage

“…Some valleys are deeply incised in the otherwise smooth and gently undulating plateau landscape. The bedrock geology is complex, comprising the northeastern border of the Scandinavian Caledonides on one side and the Fennoscandian shield on the other side (Sidlecka and Sidlecki, 1967;Johnson et al, 1978). Reconstructing the deglaciation of the area has proved difficult, due to a lack of ice marginal deposits in especially the northern and central parts of the peninsula (Meier, 1996).…”

Evidence for a glacial origin of Neoproterozoic III striations at Oaibaččannjar'ga, Finnmark, northern Norway

“…Table 1. Generalized stratigraphy of the Neoproterozoic sequence at the western end of Varangerfjord, with simplified sedimentary facies interpretation (from Johnson, Levell & Siedlecki, 1978;Siedlecka & Roberts, 1992) Group or Archaean basement. Subsequently, erosion at the base of the Mortensnes Formation (the second glacigenic unit) cut down through the Nyborg and much of the Smalfjord Formation.…”