Swiss Journal of Geosciences

, Volume 106, Issue 1, pp 91–107

Growth-strata geometry in fault-propagation folds: a case study from the Gafsa basin, southern Tunisian Atlas

Article

Abstract

The structural and sedimentological study of fault-propagation folds in Southern Tunisia highlights a special geometry of the growth strata (strata deposited simultaneously with the formation or growth of a fold). This distinct geometry is visible in the uppermost growth-strata beds and consists of one flank with unconformity as opposed to the other flank with perfect conformity. This geometry can be explained by the mechanism of fault-propagation folding, with asymmetrical flank dips and hinge migration kinematics. This kinematics was originally predicted by the fault-propagation fold model, which facilitates the study of this special geometry in a narrow domain of sedimentation-to-shortening ratios. A plot projection provides a generalisation of the results of all types of fault-propagation folds by revealing the expected geometry of the growth strata. This study constitutes one of the most complete examples of kinematic model validation on a field scale.

Keywords

Tunisian Atlas Fold mechanisms Fault-related folding Growth-strata Fold hinge migration 

Supplementary material

15_2013_122_MOESM1_ESM.jpg (1013 kb)
Detailed geological map of Gafsa basin (JPEG 1013 kb)
15_2013_122_MOESM2_ESM.jpg (2.3 mb)
Detailed correlation of southern Sehib and Khasfa growth-strata logs. Facies interpretation made it possible to distinguish climate changes and to establish climatic correlation of the main Neogene crises (Messinian and Villafranchian). Alluvial sequences stacking based on grain size analysis indicates tectonic activities in a constant base level condition. Sea level variation and glacial maximum are from Van Vliet-Lanoë (2005) (JPEG 2311 kb)
15_2013_122_MOESM3_ESM.jpg (1.2 mb)
Photography and interpretation of deformed Recent encrusted pediments. Pediment number one has been dated at 160 ka BP using archaeological tools (Ben Ouezdou 1989) and 150 ka BP using Ur/Th radiometry (Swezey 1996) (JPEG 1212 kb)

Copyright information

© Swiss Geological Society 2013

Authors and Affiliations

  1. 1.Laboratoire LR3EEcole Nationale d’Ingénieur de SfaxSfaxTunisie
  2. 2.Planétologie et Géodynamique (UMR 6112)Université de NantesNantes Cedex 3France

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