Implications of Controlling Fault
Geometry on the Structural and
Sedimentary Development of Extensional Systems: Zeta-Snorre
Fault
System,
Northern North Sea, Norway
Douglas A. Paton1 and John R. Underhill2
1 Grant Institute of Earth Sciences, Edinburgh EH9 3JW United Kingdom, Potsdam, Germany
2 School of GeoSciences, University of Edinburgh, Edinburgh, United
Kingdom
Two commonly cited end-members for normal fault
geometries are steeply
dipping planes in a domino-
fault
block configuration, and shallow dipping planes
with associated rollover geometries. We document the presence of both of these
end-members in a single basin (Tampen Spur, North Viking Graben, Norway) and
demonstrate the profound impact that
fault
geometry has on the basin's
structural and sedimentological evolution.
The south of the basin comprises the Snorre-Zeta fault
hangingwall in the
west and the Visund footwall in the east. Both faults have a steep dip (~ 45°)
with little internal deformation between them, therefore conforming to a
domino-
fault
block model. In contrast, the north comprises the shallower dipping
Zeta
fault
(~30°) with no eastern bounding
fault
. Deformation in the northern
intra-basin setting is significantly greater with arrays of synthetic and
antithetic faults similar to that associated with listric
fault
rollover
geometries.
This variation in structural style has a profound affect on sedimentation
and depocentre configuration. The south has a single depocentre adjacent to the
bounding fault
that forms early in the syn-rift phase with a deep water
depositional environment during the late rift phase. In contrast, the rollover
geometry in the north results in the establishment of a number of
fault
arrays
and smaller depocentres that are conduits for sediment dispersal and associated
footwall flanks that act as local sources of sediment. These faults develop in
accordance to established
fault
growth models with gradual localisation of
strain towards the east onto a smaller population of larger displacement, longer
faults.
AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005