Evolution of thrust system deformation in an intracratonic chain: Study of the Southern-Central Tunisian Atlas |
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| Authors: | Mohamed Sadok Bensalem Mohamed Hedi Bensalem Amira Ayed Khaled Soulef Amamria Mohamed Ghanmi Fouad Zargouni |
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| Institution: | 1. University of Gabes, Faculty of Sciences, Research Unit of Geomatics, Structural Geology and Application, Erriadh City, 6072, Gabes, Tunisia;2. University of Tunis El Manar, Research Unit of Geomatics, Structural Geology and Application, 2092, El Manar, Tunisia |
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| Abstract: | The development of belt structures in intracratonic chains is guided by the convergence system. In the Southern-Central Tunisian Atlas, several parameters control the evolution of thrust folds during different tectonic phases. One of these phases is tectonic inheritance, which leads to the reactivation of pre-existing normal faults during compressive phases. The angle between the direction of these faults and the shortening axis (NNW-SSE) is the most important parameter for interpreting the mode of the evolution of thrust folds. Jebel Elkebar is an example of a structure developed on NW-SE-oriented faults that is perpendicular to the shortening axis. Based on the geometry of its folds, Jebel Elkebar is interpreted as a 'Fault Related Fold'. The E-W-oriented Orbata structure is oblique to the direction of the shortening axis and is interpreted through the model 'Fault Propagation Fold' with 'Breakthrough'. The Gafsa Fault, which is parallel to the shortening axis, is a transpressional fault interpreted through the 'Strain Partitioning' mode, which is associated with the oblique ramp fold. The development of various thrust folds requires the presence of a basal decollement level during the Triassic succession. In the Southern-Central Tunisian Atlas, the deformation is variable (geometry of fold closure) and is correlated with the depth of the decollement level; indeed, the intensity of deformation is proportional to the depth of the decollement level. Consequently, the most important deformation is in the higher successions and is a vertical migration of the decollement level associated with thin-skinned deformation. |
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| Keywords: | Intracratonic chains Tectonic inheritance Shortening axis Decollement level Thin skinned Vertical migration |
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