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Permo-Triassic fault lineaments has been docu-
mented by several authors (Fält et al ., 1989;
Helland-Hansen et al ., 1992; Fjellanger et al .,
1996). This phase correlates directly to rifting,
convincingly, as the syn-sedimentary tectonic
signs stand out (on seismic data). The earlier stage
of rifting is more difficult to discern (Davies et al .,
2000). However, as demonstrated in this study,
the sedimentary responses to early stages of rifting
can be identified.
lation caused the added accommodation space
which, in sum, created the wedge-shaped Ness
and Tarbert formations, in accordance with
general models of rift-initiation (Gawthorpe &
Leeder, 2000; Sharp et al ., 2000; Davies et al .,
2000).
3 These data indicate that fault activity in the
Gullfaks-Kvitebjørn transect area (Figs. 4 and 6)
was initiated earlier than faulting in the East
Shetland Platform and Horda Platform, where a
similar development has been reported for the
Tarbert Formation. The location of the
Kvitebjørn footwall with respect to the Viking
Graben step-over (Fossen et al . 2010) can
explain the early faulting (footwall flexure and
collapse).
4 The wedge-shaped Ness-Tarbert formations
(Figs 4 and 6) show internal trends in the form
of low net-to-gross ratios and the trapping of
landward-supplied sediments toward the hang-
ingwall area. Footwall areas have higher net to
gross ratios and poorer preservation of strata.
These trends are the result of the variable depo-
sitional pattern that occurs along the strike of a
rotating fault-block.
5 The advancement of the 'Brent delta' was
halted due to several factors: northward
increasing water depth; over-extension of the
delta-front that exhausted its sediment supply
budget; and, probably most importantly,
increased rates of fault movements, leading to
increased subsidence. This fault initiation
caused irregular delta-front morphology at the
northern extension of the 'Brent delta' (Fig. 11).
Footwall areas were prone to progradational
facies-stacking patterns while the hangingwall
areas developed more aggradational stacking
patterns. This fault-influenced irregular delta
front became increasingly irregular, with
increased tectonic topography, as the faults
moved and the coastline retreated southwards.
This led to the development of an estuarine
environment in the hangingwall area and spit/
shoreface-development in the footwall area
(Fig. 14). Originally weak tidal currents operat-
ing at the delta front were enhanced into strong
tidal currents due to the funnel-shaped coastal
morphology created by the flooded hanging-
wall of the fault-blocks. This motif of a com-
plex shoreline morphology shifted southwards
with time into the South Viking Graben due to
the southward extension of the rift-activity in
the Late Jurassic.
CONCLUSIONS
Seismic, well and core data from the northern
North Sea have been integrated in an attempt to
constrain when and how Jurassic rifting affected
the Jurassic succession in the Tampen area; in par-
ticular with respect to the depositional environ-
ments of the Brent Group. We conclude that:
1 The Gullfaks-Kvitebjørn mega-block shows
fault-displacement on the East Statfjord fault
during the Jurassic period in a manner similar
to the Ninian-Hutton-Dunlin fault (Hampson
et al ., 2004). These faults originated in the
Permo-Triassic and produced mega-blocks that
either continued to be active throughout the
Triassic and Jurassic or were reactivated in the
Late Triassic-Early Jurassic. We suggest a model
wherein a few weak and favourably oriented
Permo-Triassic faults remained active through-
out the Jurassic and where the onset of the
Middle-Late Jurassic rift phase populated the
early mega-blocks with smaller faults that
developed into mature Late Jurassic fault popu-
lations over time.
2 The onset of Middle-Late Jurassic rifting in
the northern Viking Graben is reflected by the
wedge-shaped Ness-Tarbert formations by
means of regional well-correlations (Fig.  4)
across the Kvitebjørn Field (Fig. 6), where rift-
ing appears to have initiated during deposition
of the lowermost part of the Ness Formation at
that location. This interpretation agrees with a
model where 'base Ness sandstone units' were
deposited within local depocentres formed by
normal faults in the early rift phase. This pat-
tern of normal faults and their associated local
depocentres developed into a more mature
fault population, as some of the small faults
linked up to form larger faults that took over
much of the fault activity. The early fault popu-
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