Abstract
On the basis of sedimentary fill, tectonic style and crustal structure,
the study area may be divided into three main geological provinces,
separated by major fault zones: (1) the oceanic Lofoten Basin and
the Vestbakken Volcanic Province in the west; (2) the south-western
Barents Sea basin province; and (3) the eastern region which has
acted as a largely stable platform since Late Palaeozoic tirnes.
The seismic stratigraphy, calibrated with lithostratigraphic units
in exploration wells, has provided the timing of the main tectonic
events. The structural evolution of the south-western Barents Sea
since Middle Jurassic times comprises two main stages: Late Mesozoic
rifting and basin formation, and Early Tertiary rifting and opening
of the Norwegian-Greenland Sea. The basin formation was controlled
by pre-existing structural elements which were probably established
in Late Palaeozoic times. The Late Mesozoic-Cenozoic evolution reflects
the main plate tectonic episodes in the North Atlantic-Arctic breakup
of Pangea. The Middle-Late Jurassic and Early Cretaceous structuring
were characterized by regional extension accompanied by strike-slip
adjustments along old structural lineaments developing the Bj\\\ørn\\\øya,
Troms\\\and Harstad Basins as prominent rift basins. The Late
Cretaceous development was more complex with extension still dominating
west of the Senja Ridge and the Veslem\\\High, while halokinesis
and continued thermal subsidence prevailed in the Troms\\\Basin.
The Tertiary structuring was related to the two-stage opening of
the Norwegian-Greenland Sea and the formation of the predominantly
sheared western Barents Sea continental margin. The tectonic activity
was shifted towards the west in successive phases. The south-western
Barents Sea basin province developed within the De Geer Zone in a
region of rift-shear interaction, having affinities to both the North
Atlantic and Arctic regions; initially, as an area of oblique extension
linking the Arctic and North Atlantic rift systems (Middle Jurassic-Early
Cretaceous), then in a continental megashear setting (Late Cretaceous-Palaeocene),
and finally a combined sheared-rifted margin setting during opening
of the Norwegian-Greenland Sea (Eocene-Present).
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