Tectonic influence on the Jurassic sedimentary architecture in the northern North Sea with focus on the Brent Group - From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin - page 390

2°0 ′ 4°0 ′

211 33 34 35 36

210

2

3

Unst
Basin

61°0 ′ N

1

4

29 30 31 32

3

East
Shetland
Platform

East
Shetland Basin

Wells used in this study
Permo-Triassic faults
used in this study
Permo-Triassic faults
not evaluated in this study
Permo-Triassic faults
reactivated in Late Jurassic
Middle to Late Jurassic faults
1 Cross-section, see Figure 4
2 Cross-section, see Figure 5A
3 Cross-section, see Figure 5B
4 Cross-section, see Figure 6

Horda
Platform

Platform areas
Basinal areas
Graben areas

0 50 km

60°0 ′ N

Fig. 1. Main structural elements of the northern North Sea with indication of cross-sections and wells used. Modified from
Færseth (1996).

Middle-Late Jurassic (Leeder, 1983; Badley et al .,
1988; Rattey & Hayward 1993; Færseth et al .,
1997). The details regarding the timing, signifi-
cance and lateral extent of the Permo-Early
Triassic stretching has been a matter of debate for
a long time (Giltner 1987; Gabrielsen et al ., 1990,
Færseth et al ., 1995a; Roberts et al ., 1995;
Færseth, 1996). Large tilted fault-blocks bounded
by master-faults with throws of the order of
several kilometres formed in a 150 km wide,
north-south oriented basin in the Late Palaeozoic.
During the thermal subsidence that followed the
rifting, faulting occurred on both margins (Steel
& Ryseth, 1990) due to the interaction between
lateral variations in thermal subsidence, sedi-
ment loading, compaction and flexure (Badley
et al ., 1988).

Precise dating of the initiation of the Jurassic
rifting has also been the subject of debate (e.g.
Gabrielsen et al ., 1990). Evidence of increased
subsidence and early fault-block rotation in
Bajocian-Bathonian times has led many workers to
conclude that rifting was initiated at this time
(Badley et al ., 1988; Helland-Hansen et al ., 1992;
Ravnås et al ., 1997). Permo-Triassic master-faults
were reactivated during the Jurassic rifting and,
together with newly-formed Jurassic master-faults,
influenced the general structural pattern of the
entire basin, promoting segmentation and control-
ling the subsidence pattern in some areas (Yielding
et al ., 1992; Færseth, 1996; Odinsen et al ., 2000a;
Hampson et al ., 2004).
The Brent Group (Fig. 2) is the main reservoir
unit in the northern North Sea and its development