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| Titel |
3D modelling in salt tectonic context: the Crocodile minibasin in Sivas (Turkey) |
| VerfasserIn |
Pauline Collon, Alexandre Pichat, Charlie Kergaravat, Arnaud Botella, Guillaume Caumon, Océane Favreau, Gaétan Fuss, Gabriel Godefroy, Marine Lerat, Antoine Mazuyer, Marion Parquer, Julien Charreau, Jean-Paul Callot, Jean-Claude Ringenbach |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250112157
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| Publikation (Nr.) |
 EGU/EGU2015-12313.pdf |
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| Zusammenfassung |
| Impermeable, with a low density and acting as a viscous fluid at the geological time scale,
salt plays a unique tectonic role favouring hydrocarbon trap formations. Halokinetic
structures are various and difficult to image with classic seismic techniques. Thus, outcrop
analogues are precious and sought after. Since the re-interpretation in September 2011 of its
evaporite deposits, the Oligo-Miocene basin of Sivas (Turkey) is a new choice analogue for
the study of salt tectonic with outstanding outcrops reflecting the variety of salt related
structures: minibasins, diapirs, welds... While studying these structures requires an
important field work, building 3D models becomes an interesting way to better help
understanding the three-dimensional organisation and to further perform numerical
simulations (e.g., restoration, potential field measurement campaign simulation). The
complex geometries observed in salt tectonic context make these 3D geological
models particularly challenging to build, especially when only outcrops data are
available.
We focus on the Crocodile minibasin (Sivas) and present a modelling strategy using a
subtle combination of recently developed techniques. Available data are: a Digital Elevation
Model, satellite images and associated interpreted bedding traces on topography, orientation
measurements of the strata and a conceptual interpretation. Located on an ancient salt
extrusion, this minibasin is filled with lacustrine and sabkha sediments. It is interpreted with a
closed synclinal structure on North. On its southern part, a central diapir has risen up,
separating two tightened synclinals. The salt surface is modelled first as a triangulated surface
using a classical explicit surface patch construction method and a manual post-process mesh
improvement. Then, the minibasin sediments are modelled with an implicit approach
that considers interfaces as equipotentials of a 3D scalar field. This requires to
build a volumetric mesh conformable to the salt surface to consistently disconnect
both minibasin parts. This step is performed thanks to a local simplification of the
salt surface that consists in replacing pinched parts by an equivalent fault/weld
surface. The 3D scalar field is then computed with a Discrete Smooth Interpolation
constrained by several information. Those information are weighted consistently
with their relative uncertainty. Control points impose locally the scalar field value.
They are set on interpreted bedding traces and on a surface located at 5m from the
external salt surface boundary to account for the tangency of the sediment deposits
in conformable parts of the minibasin. They are completed by constraints on the
scalar field gradient orientation using dip measurements and a constant gradient
constraint.
The result highlights the remarkable geometry of this salt-tectonic related structure and
underlines the usefulness of new modelling methods to ease a more automated generation of
such tectonic features. |
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