The development of orogenic belts structures in the Southern-Central Tunisian Atlas is influenced by the evolution of tectonic activities during different phases,which are also closely linked to the formation of gravi...The development of orogenic belts structures in the Southern-Central Tunisian Atlas is influenced by the evolution of tectonic activities during different phases,which are also closely linked to the formation of gravitational collapse structure.The typical example is that of the northern flank of the Jebel Orbata particularly the Ben Zannouch fold.It is an asymmetrical anticline interpreted by the model of“Fault Propagation Folds”.The development of the Ben Zannouch structures is resulted from landslides,scree falls and inverted layers plunging to the south.The direction of resulted gravitational structure is parallel to the main thrust direction of the Bou Omrane anticline.The thrust activity of Bou Omrane fault is associated to the important paleo-slope facing south and plastic lithology(incompetent marl layers)of outcropped series,facilitates the development of the Ben Zannouch Flap structure.The definition of gravitational collapse structures for the first time in Tunisia particularly in the northern flank of the Jebel Orbata is controlled by many principal structural conditions:fragmentation of the landslide surfaces,rheology and topography.Other regional factors can be distinguished in the Southern-Central Tunisian Atlas as the seismic activity of the pre-existing Gafsa fault reactivated during compressive phases and the weather conditions during the postglacial period.展开更多
One of the principal parameters to study the tectonics deformation is the relation between the shortening axis and the direction of preexistent principal fault. It is important to verify this parameter in the belts st...One of the principal parameters to study the tectonics deformation is the relation between the shortening axis and the direction of preexistent principal fault. It is important to verify this parameter in the belts structures. The aim of this contribution is to check this notion in the Atlassic structures, especially in the southern limit of Tunisian Atlas: Gafsa fault. The strain partitioning model proposed in the interpretation of geodynamics of Gafsa chains suggests the coexistence of thrusting and strike-slip faults during the same tectonics phase. The application of this model requires a particular geometry between the shortening axis and the direction of fault, and indeed the obliquity of preexistent faults by the reported shortening axis interprets us a transpressive context. The slickenside examination shows the coexistence of thrusting and strike-slip faults. The application of model of strain partitioning requires a decollement level which is confirmed in the Gafsa basin by the upper level of Triassic series. These parameters confirm a particular relation thin and thick-skinned and the maximum of deformation is cover, although the basement structures permeate simple passive transport of the deformation along the Triassic decollement level. These problems confirm the assumption of the evolution of the shortening axis during geological events and especially the rotation of Africa and Eurasia.展开更多
The aim of this contribution is the interpretation of intracratonic chains in African plates, but it is important to verify some parameters such us the oblique convergence between Africaand Europa plates. Particularly...The aim of this contribution is the interpretation of intracratonic chains in African plates, but it is important to verify some parameters such us the oblique convergence between Africaand Europa plates. Particularly In southern central of atlassic Tunisian belts, the slickenside examination of directional preexisting faults of N120 direction shows the coexistence of thrusting and strike-slip faults striation. In the limits of these faults principally in some tectonics lens we distinguish abnormal contacts with Triassic facies. The kinematic evolution of Gafsa basin resumed in the geometry of strike-slip faults connected in the thrusting system, this movement resulted from the oblique convergence on Ben Younes, Bou Ramli and Attig chains during compressive phases. This deformation style requires a shortening axis oblique to the NW-SE accidents (N120). The strain partitioning model verify the geometry of faults and equivalent evolution of folds and confirms the Triassic decollement level but without integrated of basement structures in the deformation. It permeated a passive transport of deformation observed in cover structure.展开更多
基金supported by the Tunisian Ministry of Higher Education and Scientific Research,particularly Research Laboratory Geosystems,Goresources and Goenvironments LR21ES05 at the Faculty of Sciences Gabès。
文摘The development of orogenic belts structures in the Southern-Central Tunisian Atlas is influenced by the evolution of tectonic activities during different phases,which are also closely linked to the formation of gravitational collapse structure.The typical example is that of the northern flank of the Jebel Orbata particularly the Ben Zannouch fold.It is an asymmetrical anticline interpreted by the model of“Fault Propagation Folds”.The development of the Ben Zannouch structures is resulted from landslides,scree falls and inverted layers plunging to the south.The direction of resulted gravitational structure is parallel to the main thrust direction of the Bou Omrane anticline.The thrust activity of Bou Omrane fault is associated to the important paleo-slope facing south and plastic lithology(incompetent marl layers)of outcropped series,facilitates the development of the Ben Zannouch Flap structure.The definition of gravitational collapse structures for the first time in Tunisia particularly in the northern flank of the Jebel Orbata is controlled by many principal structural conditions:fragmentation of the landslide surfaces,rheology and topography.Other regional factors can be distinguished in the Southern-Central Tunisian Atlas as the seismic activity of the pre-existing Gafsa fault reactivated during compressive phases and the weather conditions during the postglacial period.
文摘One of the principal parameters to study the tectonics deformation is the relation between the shortening axis and the direction of preexistent principal fault. It is important to verify this parameter in the belts structures. The aim of this contribution is to check this notion in the Atlassic structures, especially in the southern limit of Tunisian Atlas: Gafsa fault. The strain partitioning model proposed in the interpretation of geodynamics of Gafsa chains suggests the coexistence of thrusting and strike-slip faults during the same tectonics phase. The application of this model requires a particular geometry between the shortening axis and the direction of fault, and indeed the obliquity of preexistent faults by the reported shortening axis interprets us a transpressive context. The slickenside examination shows the coexistence of thrusting and strike-slip faults. The application of model of strain partitioning requires a decollement level which is confirmed in the Gafsa basin by the upper level of Triassic series. These parameters confirm a particular relation thin and thick-skinned and the maximum of deformation is cover, although the basement structures permeate simple passive transport of the deformation along the Triassic decollement level. These problems confirm the assumption of the evolution of the shortening axis during geological events and especially the rotation of Africa and Eurasia.
文摘The aim of this contribution is the interpretation of intracratonic chains in African plates, but it is important to verify some parameters such us the oblique convergence between Africaand Europa plates. Particularly In southern central of atlassic Tunisian belts, the slickenside examination of directional preexisting faults of N120 direction shows the coexistence of thrusting and strike-slip faults striation. In the limits of these faults principally in some tectonics lens we distinguish abnormal contacts with Triassic facies. The kinematic evolution of Gafsa basin resumed in the geometry of strike-slip faults connected in the thrusting system, this movement resulted from the oblique convergence on Ben Younes, Bou Ramli and Attig chains during compressive phases. This deformation style requires a shortening axis oblique to the NW-SE accidents (N120). The strain partitioning model verify the geometry of faults and equivalent evolution of folds and confirms the Triassic decollement level but without integrated of basement structures in the deformation. It permeated a passive transport of deformation observed in cover structure.
