2024-03-29T06:55:51Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/1628182018-07-19T11:14:21Zcom_10261_82com_10261_8col_10261_461
Extension, sedimentation and diapirism: understanding evolution of diapiric structures in the Central High Atlas using analogue modelling
Moragas, Mar
Vergés, Jaume
Nalpas, Thierry
Saura, Eduard
Martín-Martín, J. D.
Messager, G.
Hunt, David W.
sedimentation
models
diapirism
Analogue modelling has proven to be an essential tool for the study and analysis of the mechanisms involved in
tectonic processes. Applied to salt tectonics, analogue modelling has been used to understand the mechanisms that
trigger the onset of diapirs and the evolution of diapiric structures and minibasins. Analogue modelling has also
been applied to analyse the impact of the progradation of sedimentary systems above a ductile layer, representing
the source of diapirs. However, these models did not consider ongoing tectonic processes during progradation.
To analyse how extension and sedimentary progradation influence on the formation of diapiric structures
and their geometries, we present models composed of a mildly extension followed by post-extension period. Each
model includes a particular sedimentary pattern: homogeneous sedimentation during extension and post-extension,
homogeneous sedimentation during extension followed by prograding sedimentation during post-extension and
prograding sedimentation during both extension and post-extension.
Proximal high sedimentation rates enhance the mobilization of ductile material towards growing diapirs,
resulting well-developed passive diapirs. Diapirs from distal domain of the model with post-extension progradation
show silicone extrusions, that are caused by the decreased sedimentation rate associated to the progradation.
By contrast, reduced sedimentation in the distal part of the model with syn- and post-extension progradation (3.5
times smaller than in the proximal domain) causes a limited migration of the silicone and hampers the transition
from reactive diapirs to active and passive diapirs. These models show that the ratio between diapir growth and
sedimentation rate, the time of the onset of the progradation and the relative thickness of the sedimentary cover
beneath the prograding system have a clear impact on the final diapiric geometries.
Additionally, we present two models with increasing amounts of shortening (6% and 10%). These models
show that the presence and location of diapirs clearly controls the distribution of the deformation associated with
the inversion, primarily affecting the post-diapiric layers in the vicinities of the salt structures whereas very little
deformation occurs away from diapirs.
This deformation pattern is observed in the Early to Middle Jurassic Tazoult salt wall and Azourki diapir
of the Central High Atlas (Morocco). These structures show that the deformation associated with the Alpine
orogeny is focused on the sedimentary units fossilizing the salt structures and mainly localised above them. The
presented results provide key information that can be applied to other diapiric structures of the Central High Atlas
diapiric basin and similar examples elsewhere.
This study was part of a collaborative research project funded by Statoil Research Centre, Bergen (Norway).
Additional funding by the CSIC-FSE 2007-2013 JAE-Doc postdoctoral research contract (E.S.), the projects
Intramural Especial (CSIC 201330E030) and MITE (CGL 2014-59516). and by the Grup Consolidat de Recerca
>Geologia Sedimentària> de la Generalitat de Catalunya (2014GSR251). We are grateful to Statoil for its support
and permission to publish this study.
Peer Reviewed
2018-03-23T10:59:20Z
2018-03-23T10:59:20Z
2017-04-23
2018-03-23T10:59:20Z
comunicación de congreso
http://purl.org/coar/resource_type/c_5794
issn: 1029-7006
Geophysical Research Abstracts, 19: EGU2017-4699 (2017)
http://hdl.handle.net/10261/162818
Publisher's version
Sí
open
European Geosciences Union