Journal of Advanced Research in Science and Technology
Volume 3, Numéro 2, Pages 324-341
2016-06-01
The Parameters Controlling The Deformation In The Structures Associated To Gafsa Fault (southern-central Tunisian Atlas): Interpretation Of “partitioning Deformation” Model
Authors : Amamria Soulef . Bensalem Mohamed Sadok . Mercier Eric . Ghanmi Mohamed . Zargouni Fouad .
Abstract
The particularity of the Gafsa basin comes from the direction of belts structures that are NW-SE different to directions of Atlassic structures in Tunisia (NE-SW to EW). These structures are affected on the core by preexisting faults. The field study associated to fine cartography allowed us to interpret the conditions of developments of structures in the Gafsa basin. The study of faults shows the role of tectonic inheritance thus the normal activity of these faults during the Cretaceous faults and its reactivations to reverse and strike-slip faults during compressive phases. The slickenside examination of the preexisting faults shows for the first time in the Gafsa basin the coexistence of thrust and strike-slip faults which is due in particular to the obliquity of the shortening axis to the direction of these faults. The geometry of folds (dissymmetrical flanks affected on the core by preexisting faults) permit to interpret the oblique “fault related fold” model associated to Triassic decollement level. The interpretation of this decollement level was confirmed by the Triassic blades that stake the main faults. The Triassic decollement level allows the separation between the deformation in the base and cover, thus the base allows only a sample passive transport and any deformation will be accommodated in cover. All these interpretations has allowed us to propose for the first time in Tunisia and across the African craton the interpretation of the "partitioning deformation" model in the genesis and development of belts structures in the Gafsa basin.
Keywords
Gafsa basin, decollement level, partitioning deformation
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