Tectonic control on sedimentation, erosion and redeposition of Upper Jurassic sandstones, Central Graben, North Sea - From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin - page 474

structural development of the area but argue that
the movement of the salt was, in many cases, trig-
gered by reactivation of deeper fault zones and, as
such, was passively deformed during the struc-
tural development. Other authors (e.g. Erratt,
1993; Helgeson, 1999) were more interested in
demonstrating the importance of Zechstein salt in
the mechanical decoupling between basement
Rotliegend fault blocks and the overlying Triassic.
They showed examples of the relationship
between faulting and halokinesis that focused on
the interaction of basement tectonics and pod/
interpod complexes. In the view of these authors,
a pure extensional setting existed in the Central
Graben with structures in the Triassic-Jurassic
carapace influenced by extension and halokine-
sis. An alternative interpretation is that an
oblique-slip regime had existed in the Central

Graben (Bartholomew et al ., 1993; Sears et al .,
1993) with the local development of transpres-
sional and transtensional domains.
The presence of two clear extensional fault
trends in the Central Graben aligned NNW-SSE
and NW-SE (Fig. 1) is interpreted by Erratt (1999)
and Davies et al . (1999) to reflect a polyphase
Jurassic extension history in which the kinematic
axes were aligned with an initial W-E extension
during the Bajocian and Bathonian and a later
NW-SE extension during the Kimmeridgian to
Volgian. The oblique-slip model places more
emphasis on the role of basement structures and
their continued influence on the structural style
of the Jurassic to explain the same trends
(Bartholomew, 1993).
Where the Zechstein salt is thick, salt tectonics
and Triassic minibasin development can very

Forties-
Montrose
High

Norway

200km

Ula

Shearwater

Studied
Region

Elgin
Figure 15

NORTH SEA

Franklin

UK

Gyda
Figure 12

Puffin

2/4-14
Figure 11

UK Sector

Jacqui
Figure 22

1/6-6 & 7

Norwegian Sector

Fulmar
Figure 10

West
Central
Shelf

Top Pre-Zechstein
(Depth, metres)

< 4500

N

4500-7500

50 km Danish Sector

7500-10000

Fig. 1. Top Pre-Zechstein simplified depth map showing location of major faults that have been reactivated by Upper
Jurassic rifting. Early developed NNW-SSE aligned extensional faults are shown in black whilst later developed NW-SE
aligned extensional faults are shown in red. The location of a geological structural section shown in Fig. 2 is indicated by
the black dotted line between white well locations. The locations of several geological sections discussed in this paper are
also indicated on the map with their associated figure numbers.