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Abstract
Rocks in the Köli Nappe Complex, originally interlayered calcareous sandstones and shales, are now amphibolite grade garbenschiefer with evidence of several phases of deformation. In the Häggsjö-Musvaltjärnen-Rensjönäset area six such phases have been recognized on overprinting criteria: D1-development of a foliation, S1, and a metamorphic layering, which were deformed during D2-flattening and development of the regional S2-foliation, lineation and minor isoclinal folds. These structures were refolded, about gently SW-plunging F3-åxes, in eastward verging asymmetrical folds in which a locally penetrative, crenulation cleavage provides the axial planar foliation, S3. The S3-foliation was deformed by open, sideways closing minor folds with an axial plane foliation, S4, accentuating the horizontal components of S2 and S3. Small-scale D5-folds verging westward warp S0 to S4. Pseudotachylite was formed during late movements, D6, in shear zones. Difficult though it may be to correlate transposed foliations and folds it has proved possible to compare the sequence of deformations in the Häggsjö-Musvaltjärnen-Rensjönäset area with sequences described from the Tärnaby, Kvarnbergsvattnet and Limingen-Tunnsjøen areas farther north on either side of the Swedish-Norwegian boundary.
Key Words:
- Polyphase deformation
- folds
- thrusting
- pseudotachylite
- schistosity
- crenulation cleavage
- axial plane foliation
- porphyroblasts
- inclusion trails
- overprinting criteria
- correlation of foliations
- garbenschiefer
- Tännforsfältet
- Häggsjö-Musvaltjärnen-Rensjönäset area
- Tärnaby area
- Kvarnbergsvattnet area
- Limingen-Tunnsjøen area
- Köli Nappes
- Caledonides
- Central Sweden
- N6333
- N6337
- E1234
- E1241