Mesozoic and Cenozoic basin configurations in the North Sea - From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin - page 440

bounding surface of the J-2 sequence and onlap-
ping patterns alongside the structure (Fig. 7). This
suggests that the feeder system migrated south-
wards, from Sognefjord at the time of deposition
of sequence J-1 to Hardangerfjord and the Lista
Fault Blocks further south, during deposition of
sequence J-2. However, we cannot rule out that
these feeder systems acted at the same time. The
truncation of the topsets of each of the prograding
sequences indicates that the available accommo-
dation space became overfilled at the end of the
depositional period for sequences J-1 and J-2, sug-
gesting that by the Late Jurassic the shoreline had
advanced basinward and was located in the
Egersund Basin, Stord Basin-Åsta Graben and the
northern Horda Platform.
According to Mitchum et al . (1977), obliquely
oriented clinoforms are common in sequences
which have been deposited in a higher-energy
environment, indicating coarse sediments and
short transport distances. Accordingly, the pres-
ence of oblique clinoforms within sequences J-1
and J-2 are interpreted to reflect increased coarse-
clastic sediment supply in the Stord Basin, Åsta
Graben and the Egersund Basin (Fig. 15A),
probably due to renewed exposure and uplift of
parts of southern Norway. Such a structural rela-
tionship between basin and hinterland is in
accordance with expected tectonic configuration
in a late syn-rift setting (e.g. Nøttvedt et al ., 1995).
An elevated Jurassic topography in southern
Norway is supported by Apatite Fission Track
studies (Rohrman et al ., 1995, 1996; Hendriks &
Andriessen, 2002; Hendriks et al ., 2007) and mor-
phological considerations (Mosar, 2003; Gabrielsen
et al ., 2010a). However, uncertainties still prevail
as to whether the whole of southern Norway was
exposed or if only local source areas were availa-
ble in latest Jurassic time. Either way, parts of the
same landmass continued to deliver sediments in
the Early Cretaceous, as indicated by the prograd-
ing sub-sequence K-2.1. This is also supported by
sand distribution patterns in the Lower Cretaceous,
which indicate that the Norwegian mainland was
supplying sediments to the North Sea Basin
(Thomson et al ., 1999; Gabrielsen et al ., 2001).
That those topographic highs continued as source
areas in Early Cretaceous time is also supported by
uplift of intra-basinal topographic highs, such as
the Utsira High (Gabrielsen et al ., 2001; Kyrkjebø
et al ., 2001). This uplift probably increased the
time duration for basin configuration 1 to through-
out Early Cretaceous; hence, a close structural

relationship between basin formation and hinter-
land tectonic uplifts, sediment supply and infill
dynamics seems to be characteristic for basin con-
figuration 1.

Basin configuration 2

At the onset of basin configuration 2, the remain-
ing topography became drowned, including
the platform areas, which is characteristic for
a typical late post-rift palaeogeographic setting
(Gabrielsen et al ., 1990, 2001, Kyrkjebø et al .,
2001). Siliciclastic sedimentation dominated in
the northern Viking Graben in a deep marine set-
ting (e.g. Gabrielsen et al ., 2001; Kjennerud et al .,
2001), with a gradual increase of chalk deposition
southwards (e.g. Surlyk et al ., 2003).
As the intra-basinal lows were filled with sedi-
ment and the structural highs were transgressed
(Gabrielsen et al ., 2001) in mid-Cretaceous time,
this gave rise to a wider and more open regional
marine basin, compared to basin configuration 1
with its sub-basins and local source areas. We
therefore suggest that the Late Cretaceous to
Danian represents a period with a different basin
configuration compared to basin configuration 1.
This also agrees with the findings of Nøttvedt
et al . (1995), who divided the early-rift and late
post-rift phases on the same criteria.

Basin development and sediment supply

The recorded thickness distribution of the Chalk
Group found in the present study (Fig. 8) is in
accordance with previous studies, where thick-
nesses up to 500 m to 800 m are seen in the
Norwegian-Danish Basin and more than 1500 m in
the Central Graben (Surlyk et al ., 2003). This may
be taken as an indication that a shallow epicon-
tinental sea persisted for a considerable time
interval as the North Sea Basin in Late Cretaceous
to Danian time. The aggradational style of chalk
facies demonstrates that the rate of pelagic car-
bonate production and sedimentation kept pace
with the rate of subsidence. The thinning of the
Chalk Group across the Coffee-Soil Fault Complex
and at the Ringkøbing-Fyn High was probably
related to tectonic inversion of the basin succes-
sion along these structures, related to Alpine com-
pression, in the Late Cretaceous (e.g. Liboriussen
et al ., 1987; Handy et al ., 2010).
The presence of the Chalk Group in the
Norwegian-Danish Basin itself indicates that no