in the North Atlantic-Arctic region. Rifting continued
in Early Cretaceous time and an important phase of
Aptian faulting is documented in the SW Barents Sea.
Several phases of Late Mesozoic and Early Cenozoic
rifting gave rise to very deep basins in the SW
Barents Sea. A tentative Middle Jurassic horizon
corresponding to the top of the shallow marine
sandstones, also marking the onset of late Mesozoic
rifting, can be followed from the seafloor down to 9 s
twt (16–17 km) over a relatively short distance
(Fig. 25.15).
The Lower Cretaceous comprises three sedimentary units from Valanginian to Cenomanian. Shales
and claystones dominate, with thin interbeds of silt,
limestone and dolomite. These strata make up the
main basin fill in the deep SW Barents Sea basins
and they dominate the regional subcrop pattern. The
marine environments throughout the deposition of
these units were dominated by distal conditions with
periodic restricted bottom circulation.
In Early Cretaceous time the northern Barents Sea
was characterised by widespread magmatism without
any signs of faulting. Extrusives and intrusives (sills
and dykes) belonging to a regional Large Igneous
Province (LIP) in the Arctic are documented from
both onshore (Svalbard and Franz Josef Land) and
offshore areas in the northern Barents Sea. The
magmatism was most extensive during Barremian?Aptian times but both older and younger dates have
been reported. The present distribution in the northern
Barents Sea is modified by later uplift and erosion. The
Early Cretaceous magmatism within the Arctic LIP
had important palaeogeographic implications. It
caused regional uplift and the Neocomian in the
north and east was characterised by southward sediment progradation. This depositional regime is difficult to document in the western Barents Sea due to
later uplift and erosion. The magmatism and regional
uplift was related to rifting and break-up in the
Amerasia (Canada) Basin and the formation of the
Alpha Ridge.
Little or no Upper Cretaceous sediments were
deposited in the Barents Sea except in the SW Barents
Sea which continued to subside in response to faulting
in a pull-apart setting. The Wandel Sea Basin is a NE
Greenland equivalent where Late Cretaceous strikeslip faulting and pull-apart basin formation is well
documented (Figs. 25.2 and 25.3). The Upper Cretaceous succession varies in thickness and
completeness. In the Tromsø Basin a 1,200 m shale
succession has been drilled while seismic data indicate
that the sequence reaches 2,000–3,000 m in rim
synclines in the central basin. Whereas the Tromsø
and Sørvestsnaget basins were depocentres through
most of this period, areas further east were either
transgressed only during maximum sea-level and/or
display only condensed sections.
25.4.2.3 Cenozoic
The Cenozoic structuring was related to the twostage opening of the Norwegian-Greenland Sea
and the formation of the predominantly sheared
western Barents Sea continental margin (Fig. 25.3).
Continental break-up and onset of seafloor spreading
were preceded by a phase of rapid late Palaeocene
subsidence. The Palaeogene succession rests
unconformably on the Cretaceous and this depositional break at the Cretaceous-Tertiary transition
(Maastrichtian-Danian) occurs throughout the southwestern Barents Sea.
The western Barents Sea-Svalbard margin developed from a megashear zone which linked the
Norwegian-Greenland Sea and the Eurasia Basin during the Eocene opening. The first-order crustal structure along the margin and its tectonic development is
mainly the result of three controlling parameters: (1)
the pre-break-up structure, (2) the geometry of the
plate boundary at opening and (3) the direction of
relative plate motion. The interplay between these
parameters gave rise to striking differences in the
structural development of the different margin
segments of sheared and/or rifted nature. The
continent-ocean boundary is clear along the sheared
Senja margin. The central rifted margin segment
southwest of Bjørnøya was associated with
magmatism in the Vestbakken Volcanic Province
both during break-up at the Palaeocene-Eocene transition and later in the Oligocene. In the north, strike-slip
movements between Svalbard and Greenland gave rise
to compressional (transpressional) deformation within
the Spitsbergen Fold and Thrust Belt (Fig. 25.17).
Compressional deformation is also observed in the
Barents Sea east of Svalbard, showing that stress
related to transpression at the plate boundary west of
Svalbard was transferred over large distances. Domal
structures observed in the eastern Barents Sea may be
related to this compressional regime.
632
J.I. Faleide et al.
in Early Cretaceous time and an important phase of
Aptian faulting is documented in the SW Barents Sea.
Several phases of Late Mesozoic and Early Cenozoic
rifting gave rise to very deep basins in the SW
Barents Sea. A tentative Middle Jurassic horizon
corresponding to the top of the shallow marine
sandstones, also marking the onset of late Mesozoic
rifting, can be followed from the seafloor down to 9 s
twt (16–17 km) over a relatively short distance
(Fig. 25.15).
The Lower Cretaceous comprises three sedimentary units from Valanginian to Cenomanian. Shales
and claystones dominate, with thin interbeds of silt,
limestone and dolomite. These strata make up the
main basin fill in the deep SW Barents Sea basins
and they dominate the regional subcrop pattern. The
marine environments throughout the deposition of
these units were dominated by distal conditions with
periodic restricted bottom circulation.
In Early Cretaceous time the northern Barents Sea
was characterised by widespread magmatism without
any signs of faulting. Extrusives and intrusives (sills
and dykes) belonging to a regional Large Igneous
Province (LIP) in the Arctic are documented from
both onshore (Svalbard and Franz Josef Land) and
offshore areas in the northern Barents Sea. The
magmatism was most extensive during Barremian?Aptian times but both older and younger dates have
been reported. The present distribution in the northern
Barents Sea is modified by later uplift and erosion. The
Early Cretaceous magmatism within the Arctic LIP
had important palaeogeographic implications. It
caused regional uplift and the Neocomian in the
north and east was characterised by southward sediment progradation. This depositional regime is difficult to document in the western Barents Sea due to
later uplift and erosion. The magmatism and regional
uplift was related to rifting and break-up in the
Amerasia (Canada) Basin and the formation of the
Alpha Ridge.
Little or no Upper Cretaceous sediments were
deposited in the Barents Sea except in the SW Barents
Sea which continued to subside in response to faulting
in a pull-apart setting. The Wandel Sea Basin is a NE
Greenland equivalent where Late Cretaceous strikeslip faulting and pull-apart basin formation is well
documented (Figs. 25.2 and 25.3). The Upper Cretaceous succession varies in thickness and
completeness. In the Tromsø Basin a 1,200 m shale
succession has been drilled while seismic data indicate
that the sequence reaches 2,000–3,000 m in rim
synclines in the central basin. Whereas the Tromsø
and Sørvestsnaget basins were depocentres through
most of this period, areas further east were either
transgressed only during maximum sea-level and/or
display only condensed sections.
25.4.2.3 Cenozoic
The Cenozoic structuring was related to the twostage opening of the Norwegian-Greenland Sea
and the formation of the predominantly sheared
western Barents Sea continental margin (Fig. 25.3).
Continental break-up and onset of seafloor spreading
were preceded by a phase of rapid late Palaeocene
subsidence. The Palaeogene succession rests
unconformably on the Cretaceous and this depositional break at the Cretaceous-Tertiary transition
(Maastrichtian-Danian) occurs throughout the southwestern Barents Sea.
The western Barents Sea-Svalbard margin developed from a megashear zone which linked the
Norwegian-Greenland Sea and the Eurasia Basin during the Eocene opening. The first-order crustal structure along the margin and its tectonic development is
mainly the result of three controlling parameters: (1)
the pre-break-up structure, (2) the geometry of the
plate boundary at opening and (3) the direction of
relative plate motion. The interplay between these
parameters gave rise to striking differences in the
structural development of the different margin
segments of sheared and/or rifted nature. The
continent-ocean boundary is clear along the sheared
Senja margin. The central rifted margin segment
southwest of Bjørnøya was associated with
magmatism in the Vestbakken Volcanic Province
both during break-up at the Palaeocene-Eocene transition and later in the Oligocene. In the north, strike-slip
movements between Svalbard and Greenland gave rise
to compressional (transpressional) deformation within
the Spitsbergen Fold and Thrust Belt (Fig. 25.17).
Compressional deformation is also observed in the
Barents Sea east of Svalbard, showing that stress
related to transpression at the plate boundary west of
Svalbard was transferred over large distances. Domal
structures observed in the eastern Barents Sea may be
related to this compressional regime.
632
J.I. Faleide et al.