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 392

(A)

Kvitebjørn
Field

Gullfaks-Kvitebjørn
megablock

(B)

Kvitebjørn
Field

Fig. 3. Fault population and fault linkage trough time during rift development. (A) Pre-rift with Permo-Triassic faults
indicated. (B) Initial rift-stage. The isolated small faults of the initial rift are interpreted to be responsible for the local
depocentres recorded within the base Ness sandstone.

• Early (initial) rift stage:
⚬ Initial rift stage is characterised by scattered
normal fault population and development of
scattered local depressions;
⚬ Fault propagation with initial fault linkage
and early fault death of some of these faults;
⚬ Initial footwall flexing;
⚬ Initial fault-block tilting;
• Main rift stage:
⚬ Transition to rift-climax is correlated with a
sharp increase in the rate of basin-wide sub-
sidence early in the rift event (e.g. Steckler
et al ., 1988). Gupta et al . (1998) suggested that
the transition from rift-initiation to rift-climax
occurs as fault activity became localised onto
linked arrays (Fig. 3). With a decline in the
number of active faults, rates of fault dis-
placement increase; hence, the rate of tectonic
subsidence increases;
⚬ Increasing degree of fault linkage and fault
death;

⚬ Escalating rotation of fault blocks and poten-
tial slumping at footwall fault crests;
⚬ Episodic fault movement leading to varia-
tions in tilt rate and accommodation space;
⚬ Footwall flexing;
• Late rift (or transition to post-rift) stage:
⚬ Reduced tilt-rates;
⚬ Submerged fault-block crests;
⚬ Initial rotation toward the rift axis of the
basin.

Generic pre-rift to syn-rift infill models

To identify the different stages within the transi-
tion from pre-rift to syn-rift in a sedimentary
basin, a set of sedimentary signatures can be
recognised within each stage, as outlined by
Yielding et al . (1992); Prosser (1993); Nøttvedt
et al . (1995); Ravnås & Steel (1998) Gawthorpe &
Leeder (2000); Sharp et al . (2000) and Nøttvedt
et al . (2000):