Tectonostratigraphic position of the Finnish Caledonides at the Fennoscandian margin of the northern Scandes

Abstract

The Finnish Caledonides consist of the lower structural units characteristic of much of the northern Scandes, whose foreland is now known to be Archaean throughout its extension in Finland. The autochthonous Dividal sedimentary rocks pass very gradually into the somewhat overthrust Jerta rocks. These are capped by the Nalganas meta-arkosites, which have undergone considerable displacement. The overlying Nabar plate consists of a lower sequence of heterogeneous amphibolite ‒ pegmatitic gneiss and an upper part of very homogeneous acidic gneiss intruded and thrust by ultramafic to mafic ophiolitic material. The origin and tectonostratigraphic correlation of the conventional Nabar Nappe are discussed in more detail, because it has features suggesting it may be part of the overlying Seve Nappe Complex. Direct proof of this is lacking, however, and so only the special characteristics of the units are discussed and comparisons made with the adjacent Norwegian and Swedish terrains. The topmost Kalak unit, the Corrovarre Nappe, also occurs in the Finnish part of the Kalak Nappe Complex.

Keywords

• stratigraphy
• tectonics
• correlation
• metamorphic rocks
• nappe
• Caledonides
• Paleozoic
• Enontekiö
• Finland