Mesozoic and Cenozoic basin configurations in the North Sea - From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin - page 439

Underhill and Partington, 1993; Nøttvedt et al .,
1995; Færseth et al ., 1997; Fraser et al ., 2002).
However, this study starts with the Late Jurassic to
earliest Cretaceous rift phase. Following the Late
Jurassic to earliest Cretaceous basin formation, the
period from earliest Cretaceous to Early Palaeocene
was ruled by the post-rift development (Gabrielsen
et al ., 2001). At this time, sedimentary strata
became gradually inclined towards the basin axis
during post-rift (Nøttvedt et al ., 1995). Hence, the
syn-rift to post-rift transition is well established
(Gabrielsen et al ., 2001; Kyrkjebø et al ., 2001).
However, the North Sea basin configuration under-
went transformations that cannot be accounted for
by post-rift related processes alone in the mid-Cre-
taceous, when the intra-basinal highs were trans-
gressed (Kyrkjebø et al ., 2001). Noting these
differences, Nøttvedt et al ., (1995) subdivided the
post-rift development into two separate phases;
namely early and late post-rift. This subdivision
was based on the sediment infilling of the graben
system, where early post-rift sedimentation took
place in areas of subsidence separated by rotated
fault blocks developed during syn-rift stage. Thus,
late post-rift sediments draped the entire graben
system, including the platform areas. In this study,
we emphasise this subdivision. In doing so we
incorporate the early post-rift phase together with
the late syn-rift phase in basin configuration 1,
because the early post-rift phase to a great extent
was governed by the late syn-rift relief. In contrast,
we see that the late post-rift phase, represented by
basin configuration 2, to a greater extent was domi-
nated by thermal cooling and associated processes
(differential sediment loading and compaction).
This is further discussed below.
Following basin configuration 2, the subsequent
basin configuration was characterised by the fol-
lowing patterns; (1) initiation of sediment trans-
portation and deposition from west in the Late
Palaeocene (basin configuration 3) and (2) a switch
from a mainly western source area to a dominantly
easterly to north-easterly source area in the
Oligocene (basin configuration 4).
Following is a discussion of the dynamics of the
changing basin configurations during the Late
Mesozoic and Cenozoic.

in the Late Jurassic to earliest Cretaceous. When
compared to this period of extension, the Horda
Platform represents a stable platform (e.g.
Gabrielsen et al ., 1990; Fraser et al ., 2002). The
deepest parts of the rift basin in the northern
North Sea were clustered along the central axis of
the Viking Graben, although accommodation
space was also created along rotated fault blocks
and graben structures on the platform areas (e.g.
Nøttvedt et al ., 1995; Odinsen et al ., 2000;
Gabrielsen et al ., 2001).
Basin configuration 1 includes the late syn-rift
and early post-rift phases. Although the syn-rift to
post-rift transition is defined by the switch from
lithospheric heating to cooling (McKenzie, 1978;
Nøttvedt et al ., 1995), a change in the basin con-
figuration is delayed due to the strong structural
impact of the late syn-rift stage prevailing into the
early post-rift (Gabrielsen et al ., 2001, Kyrkjebø
et al ., 2001). Thus, during the late syn-rift and early
post-rift phase (basin configuration 1), the North
Sea area was characterised by several emerged
structural highs (such as the Utsira High and the
Ringkøbing-Fyn High) and regional and local lows
with water depths up to 1000 metres, such as the
axis of the Viking Graben and rotated fault blocks
along its margins (e.g. Ziegler, 1987; Nøttvedt
et al ., 1995; 2002; Gabrielsen et al ., 2001; Kjennerud
et al ., 2001; Fraser et al ., 2002; Martinsen et al .,
2005). We therefore suggest that basin configura-
tion 1 includes both the late syn-rift and early
post-rift phases, incorporating the sequences J-1,
J-2 and K-2.1, as described in the present study.

Basin development and sediment supply

As the sediments belonging to the J-1 sequences in
the study area were sourced from the east, it is
probable that the terrigenous detritus was trans-
ported through sediment routes along a valley
system located at the present Sognefjord (e.g.
Gabrielsen et al ., 2010a). Simultaneously, the point
sources for the sub-sequence J-2.1 of the Stord
Basin-Åsta Graben were located at the mouth
of a river system aligned along the present
Hardangerfjord (see also Gabrielsen et al ., 2010a).
In contrast and in accordance with the dip-direc-
tion of the internal clinoforms of sub-sequences
J-2.1 and J-2.2 in the Egersund Basin, these pro-
graded from east to west. The source area has
probably been the Lista Fault Blocks, based on the
erosional surface truncating these structural
heights and which corresponds to the basal

Basin configuration 1

During basin configuration 1, the North Sea Basin
was characterised by structural highs and lows
related to the extensional regime which prevailed