Mesozoic and Cenozoic basin configurations in the North Sea - From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin - page 442

topographic highs were available in southern
Norway at this time to supply siliciclastic sedi-
ments towards the S-SW. Advanced chemical
weathering in the warm and humid climate of
northern Europe in the Late Cretaceous (Huber
et al ., 1995, 2002; Norris et al ., 2002; Friedrich
et al ., 2012) might have altered most feldspar and
other silicates into clay minerals. However, there
should still have been a lot of quartz left for depo-
sition in adjacent basins, provided sufficient relief
existed for sediment transport from a source area
in southern Norway. The north-eastward thicken-
ing of the Chalk Group in the Norwegian-Danish
Basin (i.e. thickening towards southern Norway;
Fig. 8) is here interpreted to reflect that the sea
probably covered substantial parts of South
Norway in the Late Cretaceous during the first
order eustatic highstand at this time (Haq et al .,
1987; Fig. 15B). This interpretation is supported
by the following arguments: (1) the Chalk Group
rests on an angular unconformity that cuts sedi-
mentary successions of basin configuration 1 on
intrabasinal highs, as seen at the Utsira High and
along the Øygarden Fault Complex, as well as in
depocentres, implying (2) that the formation of
this regional unconformity also affected mainland
Norway with denudation and potential peneplana-
tion, thus (3) allowing the sea to transgress across
parts of South Norway, (4) preventing large
amounts of siliciclastic sediments to be trans-
ported to the southern part of the North Sea Basin
system.
A Late Cretaceous depositional area in parts of
southern Norway is in accordance with observa-
tions by Thyberg et al . (2000), who recorded chalk
clasts, suggested to be of Late Cretaceous age, in
prograding sequences of Pliocene age in the north-
ern North Sea. However, the siliciclastic sedimen-
tary input in the northern North Sea area indicates
exposed landmasses in the surrounding areas.
Brekke (2000) suggested a western or eastern
source for the Late Cretaceous siliciclastic succes-
sion in the Møre Basin, north of the northern North
Sea, based on onlap patterns and thinning of Upper
Cretaceous strata against basin flanks in the east
and the west. This is also in harmony with Hancock
(1990), who suggested a northern source area for
the siliciclastics in the northern North Sea. Due to
the proximity, the same source area probably deliv-
ered sediments into the northern North Sea in Late
Cretaceous time as well and indicates that parts of
mid-Norway and northern Norway may have been
exposed in Late Cretaceous time. However, the

siliciclastic input ceased during Maastrichtian
time, with subsequent chalk deposition also in the
northern North Sea (Hancock, 1990).

Basin configuration 3

At the onset of basin configuration 3, uplift of the
East Shetland Platform took place, with the subse-
quent deposition of sequences CSS-1 and CSS-2
in a rapidly deepening North Sea basin (Fig. 8;
e.g. Jordt et al ., 1995, 2000; Martinsen et al ., 1999;
Kjennerud et al ., 2001; Faleide et al ., 2002;
Gabrielsen et al ., 2005, 2010a; Anell et al ., 2011).
This uplift corresponds in time with major igneous
activity in the North Atlantic Igneous Province,
north-west of the study area (e.g. Knox & Morton,
1988; White & Lovell, 1997) and an overall change
from shallow marine conditions during Late
Cretaceous to deep marine during Early Palaeogene
(Michelsen, 1994; Kyrkjebø et al ., 2001).
We propose that the onset of deposition of the
CSS-1 sequence in Late Palaeocene time repre-
sents a transition to a third basin configuration
within the study area. Deposition of the sequences
CSS-1 and CSS-2 within rapidly subsiding depo-
centres indicates new tectono-thermal conditions,
with more localised depocentres and the develop-
ment of structurally coupled source areas in the
hinterlands. This indicates that the lithospheric
properties changed, as compared to during basin
stage 2, where the study area was mainly affected
by thermal cooling and sediment loading (Nøttvedt
et al ., 1995).

Basin development and sediment supply

The outline of the sequences trapped in depocen-
tres and the eastward dipping clinoforms in the
Viking Graben area (CSS-1 and CSS-2) and in the
Central Graben area (CSS-2) indicate eastward
progradation, suggesting a westerly source in
Late Palaeocene and Eocene times. This implies a
tectonic uplift of the East Shetland Platform
(Fig. 15C), as the vast chalk sediment deposition
indicate that no source area was situated here dur-
ing basin configuration 2. At the same time, accu-
mulations of sequence CSS-1 offshore Sognefjord
and Hardangerfjord indicates uplift of north-
western parts of southern Norway. A source area
in the east in Palaeocene time is also suggested by
Dmitrieva et al . (2012), based on recordings of
proximal basin floor fan systems in the eastern
Viking Graben area and by Jordt et al . (1995, 2000)