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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: Salty Tales: Numerical Investigations of
Continental Margin 
Salt
Tectonics
Salt Tectonics
1Department of Oceanography, Dalhousie University
2Department of Earth Science, Dalhousie University
3Geological Survey of Canada
The study of continental margin salt tectonics has a long and
illustrious history. Major advances in our understanding
have come from the direct interpretation of
data supported by analogue laboratory
models. Numerical modeling of salt tectonics
has to some degree lagged behind. We will
show applications in which 2D finite
element numerical modeling of salt tectonics,
driven by gravitational spreading and
gliding, can test mechanisms proposed from
data interpretation and provide insight
beyond that of analogue models. The models
are not designed to simulate or mimic particular geological
examples. Instead we are using simplified examples to understand
the underlying mechanical controls. Armed with this
understanding we can predict the styles of salt tectonics that will
develop under differing sedimentation
regimes and explain the variations among
natural salt tectonic provinces. The models
also act as “intuition enhancers” and can
help explorationists visualize just how
dynamic salt tectonic systems can be.
Starting from the basic problem of the
large-scale failure of frictional-plastic overburden
above viscous salt and the seaward
translation of the failed margin sediments, we investigate the
requirements
for failure, the ensuing flow velocity and the way in which structural components of this system evolve. We will consider a set of archetypal problems:End_Page 11---------------
1) A dynamic model for initiation and early evolution of minibasins (when the basin sediments are less dense than the
salt);
2) An explanation of the basic styles of
salt tectonics of the
Scotian Basin, eastern Canada; and
3) The conditions required for the development of toe-of-
salt
fold belts, such as the Perdido Fold Belt of the Gulf of Mexico,
by gravitational spreading.
We use the finite element models to calculate the large-scale
deformation of the system during progradation and aggradation
of frictional sediments above salt
. Additional factors included in
the models are the syn-rift geometry of a rifted continental margin
with the associated thermal subsidence and tilting, the loading
of the margin by seawater, and finally the isostatic response to the
water and sediment loads which then modifies the margin geometry.
Within the sediments the effects of pore-fluid pressure,
which reduces their strength, and compaction, which modifies
density and accommodation, are also shown to be important.
The lecture addresses the critical controlling factors for each of the problems listed above and includes some neat animations of the models.
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