Caledonian structural evolution and tectonostratigraphy in the Rombak - Sjangeli Window and its covering sequences, northern Scandinavian Caledonides

• Main Author: Bax, Gerhard
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1989
• Subjects: TEKTONIKK; Evenes; Hamarøy; Narvik; Rautas; Rombak; Sjangeli; Skjomdalen; Skjomen
• Online Access: https://hdl.handle.net/11250/2674074

The tectonostratigraphy and Caledonian structural evolution of an area in and around the north-eastern corner of the Rombak-Sjangeli Window (RSW) in the northern Scandinavian Caledonides is described. The investigated area comprises four main tectonostratigraphic units, established during southeast-directed, piggy back thrusting onto the Baltoscandian Platform. The lowermost exposed unit is composed of Svecokarelian crystalline rocks of the allochthonous RS-complex with its Vendian to Cambrian sedimentary cover of the Gearbelj\u00E0vri Formation. Lithological and structural comparisons of this unit with the Rautas Complex in the east favour a correlation of both units. Slivers of locally derived crystalline and sedimentary rocks are arranged in isolated duplexes of the Hoiganjavri Complex. The uppermost preserved portions of the nappe sequence are dominated by metasediment of the Seve-K\u00F6li Nappe Complex. Metamorphic grade increases in tectonically higher and consequently farter-travelled nappe units. Scandian thrusting (T1) postdated the peak of Caledonian metamorphism. \"Basement\"-cover interaction can be studied around several minor windows and klippen at the northeastern margin of the RSW. Faulting in the RS-complex induced folding (partly cross-folds) in the overriding nappes during two (d3 and D4) of at least five phases of Caledonian deformation. N-S-trending high-angle faulting during D4 locally caused back-thrusting structures and was accompanied by emplacement of sulphide-bearing quartz veins. Movement along pre-existing Caledonian ductile shear zones under brittle conditions resulted in the formation of pseudotachylite. 35691