POST-CALEDONIAN STRUCTURAL EVOLUTION OF THE LOFOTEN AND VESTERALEN OFFSHORE AND ONSHORE AREAS

The Lofoten/Vesteralen land area is the only exposed basement high on the continental margin around mainland Norway. The onshore and offshor e areas went through a rapid crustal cooling From temperatures higher than 550 degrees C at maximum Caledonian metamorphism; through tempera tures around 300-400 degrees C in late Devonian/mid-Carboniferous, to surface temperature in mid-Jurassic. During the early to mid-Jurassic, a smooth, peneplained basement relief developed throughout the area. In mid-Jurassic, a period of normal faulting, subsidence and sedimenta tion was initiated and large parts of the Lofoten/Vesteralen off- and onshore areas subsided. Faulting occurred more or less continuously th roughout the mid-Jurassic to early Cretaceous, but the largest Fault m ovements took place during the early Cretaceous, presumably in Albian to Aptian times. During the early Cretaceous, the Lofoten Ridge develo ped as a horst while the surrounding areas (Vesteralen/Andoya and sedi mentary basins) subsided below a several km thick Lower Cretaceous suc cession. The final rifting phase during late Cretaceous and Palaeocene was focused west of the Utrost Ridge and Andoya, but minor faulting a lso occurred throughout the Andoya/Vesteralen/Lofoten area. During a l ate Cenozoic compressional phase the entire Lofoten and Vesteralen mar gin east of the present shelf edge was uplifted and eroded. The erosio n and resulting isostatic uplift continued throughout the glacial peri od.