Structural Geology of the Southeastern Part of the Trollfjorden-Komagelva Fault Zone 305
NORWEGIAN JOURNAL OF GEOLOGY Structural geology of the southeastern part of the Trollfjorden-Komagelva Fault Zone 305 Structural geology of the southeastern part of the Trollfjorden-Komagelva Fault Zone, Varanger Peninsula, Finnmark, North Norway Tore Herrevold, Roy H. Gabrielsen & David Roberts Herrevold, T., Gabrielsen, R.H. & Roberts, D.: Structural geology of the southeastern part of the Trollfjorden-Komagelva Fault Zone, Varanger Peninsula, Finnmark, North Norway. Norwegian Journal of Geology, vol. 89. pp. 305-325, Trondheim 2009, ISSN 029-196X. Structural studies in the Late Riphean to Vendian succession of the southeastern part of the Trollfjorden-Komagelva Fault Zone on Varanger Peninsula, Finnmark, have revealed the presence of two main sets of contractional structures, here grouped into D1 and D2 events. These folding and cleavage-forming episodes are superseded by two, separate extensional events, D3 and D4. Although only one of these four events (D3) has been directly dated in the actual study area, the probable ages of the disparate, contractional deformation episodes can be deduced from published geochronological data in neighbouring parts of Varanger Peninsula or Northwest Russia. The deformation history of this area shows the following sequence of main events: (1) Inversion of the pre-existing, Neoproterozoic, basinal regime occurred during an episode of SW-directed shortening, folding and associated cleavage development, with reverse faulting and minor sinistral strike-slip movements along the Trollfjorden-Komagelva Fault Zone. By comparison with the situation on the nearby Rybachi and Sredni Peninsu- las in NW Russia, this D1 deformation and low-grade metamorphism is likely to have occurred during the Timanian orogeny at about 570-560 ± 10 Ma.
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