Numerical models of the inversion of sedimentary basins
- Inversion of half-graben basins |
- Comparison of analogue and numerical models |
- Extension followed by inversion
© Susanne Buiter
Basin inversion is the process of shortening an extensional sedimentary
basin whereby the basin fill
is uplifted and partially extruded, and pre-existing faults are re-used
[in the sense of Cooper et al., Geological Society Special Publication
Mild to moderate basin inversion has among others been identified
on seismic profiles in the North Sea and the Alpine foreland.
It is characterised by uplift of the basin fill,
folding of syn- and post-rift sediments and
(partial) reactivation of normal faults.
Examples of strong or complete inversion can be found in
the Alps and Pyrenees. Folding, faulting, fault rotation, fault
reactivation and extrusion of the basin fill play a role in the generation
of sometimes complex deformational structures.
The pictures below give a snapshot of my basin inversion projects over the years 2002-2009.
The two-dimensional visco-plastic numerical models use Sopale, a finite-element code developed by the Geodynamics Group at Dalhousie University.
We use both analogue and numerical experiments to study the inversion by shortening of a symmetric sedimentary basin. The experiments start with a pre-existing basin filled in part with weak layers simulating weak sediments.
The figure shows an (unpublished) example of the formation of a sedimentary basin by
extension and its inversion through contraction.
The model is 400 km wide by 35 km high, and the centre 200 km of the
modelling domain are shown.
Crust is pink, sediments are yellow.
a) 50 km of extension;
b) 60 km of extension,
the different shades of yellow indicate different times of
deposition of sediments;
c) post-rift sediments;
d) 10 km contraction, note the
syn-inversion sediments in red.
The frictional strength of all model materials softens with
The grid in the figure
is used to track material properties and visualises deformation; it is
not the calculation grid (which is more dense).
The example below is from a model that features basin formation and basin inversion in models that include the lithosphere and upper mantle.
- Buiter, S.J.H., O.A. Pfiffner and C. Beaumont, 2009, Inversion of extensional sedimentary basins: A numerical evaluation of the localisation of shortening, Earth and Planetary Science Letters 288, 492-504, doi: 10.1016/j.epsl.2009.10.011