The particularity of the Gafsa basin comes from the direction of belts structures that are NW-SE ... more 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 Tria...
Optical remote sensing was used to provide scientific information to support environmental manage... more Optical remote sensing was used to provide scientific information to support environmental management in the Gulf of Gabes located on the southeastern coast of Tunisia. This region is characterized by a shallow continental shelf with semi-diurnal tides. Since the early 1970s, industrial activity in this area may have contributed to the degradation of ecosystem biodiversity due to problems of eutrophication and the disappearance of benthic and planktonic species. Previous studies assessing the long term effects of anthropogenic and natural discharges on the Gulf of Gabes were based on regular seaborne measurements of total suspended matter, Secchi depth, turbidity, chlorophyll and temperature. However, these are often costly and difficult to obtain. The objective of this study is to carry out an optical remote sensing analysis with supporting in situ measurements of chlorophyll to monitor water quality and the impact of industrial discharges in the Gulf of Gabes. To start with, data ...
Sondeos petrolíferos realizados en la plataforma sahariana al sur de Túnez han puesto de manifies... more Sondeos petrolíferos realizados en la plataforma sahariana al sur de Túnez han puesto de manifiesto la existencia de materiales precámbricos y paleozoicos. Las litologías dominantes en el Paleozoico inferior son pizarras y areniscas, mientras que el Paleozoico ...
A stratigraphic study was carried out on the Jebel Boulahouajeb section (Lansarine Chain; Tebourb... more A stratigraphic study was carried out on the Jebel Boulahouajeb section (Lansarine Chain; Tebourba area, northern Tunisia) in order to establish a relatively detailed biostratigraphic framework of the Hauterivian pelagic deposits of the Tunisian trough. The limestone-marl alternations are represented by five limestone-dominated intervals, named calcareous bundles H1 to H5, separated by thick marly-dominated intervals. The well exposed Jebel Boulahouajeb section (873 m in thickness) is relatively continuous, rich in ammonoid macrofauna, and provides an ideal succession for this approach. Concerning the Hauterivian ammonoid zonal scheme, the following (sub-)zones have been identified: Acanthodiscus radiatus, Crioceratites loryi, Lyticoceras nodosoplicatum, Balearites balearis (with B.
Comptes Rendus de l'Académie des Sciences - Series IIA - Earth and Planetary Science, 1999
Slim-Shim& 1992). The l/50 000 geological map (Rouvier, 7988) of the studied area shows four lith... more Slim-Shim& 1992). The l/50 000 geological map (Rouvier, 7988) of the studied area shows four lithostratigraphic groups: marls and limestones, including Abiod Formation (Upper Cretaceous), El Haria Formation (Early Eocene), Metlaoui Formation (Middle Eocene) and Souar Formation (Middle Eocene to Early Oligocene); Note p&sent&e par Michel Durand-Delga.
The aim of this contribution is the interpretation of intracratonic chains in African plates, but... more 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 Africa and 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.
Optical remote sensing was used to provide scientific information to support environmental manage... more Optical remote sensing was used to provide scientific information to support environmental management in the Gulf of Gabes located on the southeastern coast of Tunisia. This region is characterized by a shallow continental shelf with semi-diurnal tides. Since the early 1970s, industrial activity in this area may have contributed to the degradation of ecosystem biodiversity due to problems of eutrophication and the disappearance of benthic and planktonic species. Previous studies assessing the long term effects of anthropogenic and natural discharges on the Gulf of Gabes were based on regular seaborne measurements of total suspended matter, Secchi depth, turbidity, chlorophyll and temperature. However, these are often costly and difficult to obtain. The objective of this study is to carry out an optical remote sensing analysis with supporting in situ measurements of chlorophyll to monitor water quality and the impact of industrial discharges in the Gulf of Gabes. To start with, data ...
Abstract The Kechabta Basin is part of the Tunisian Foreland Basin in front of the Numidian and T... more Abstract The Kechabta Basin is part of the Tunisian Foreland Basin in front of the Numidian and Tellian nappes. During the Tortonian, this basin records a strong subsidence rate due to flexural process, in front of the nappes. Contrary to previous interpretations, a sedimentological investigation of the thick Tortonian-Early Messinian Kechabta Formation (over 1300 m) reveals that this siliciclastic series corresponds to a complex deltaic shorelines deposit dominated by waves and influenced by tides. This formation is mainly made of a large number of high frequency, mudstone to sandy prograding parasequences representing repeated progradational phases of the coastal wedge. Facies successions within many of the parasequences show normal regressive trends. These parasequences present offshore grey-brown mudstone, followed by transition offshore sandy storm beds alternating with mudstone, then by shoreface sandstones bearing hummocky-cross stratification and wave ripples, then by foreshore facies or tidal flat facies. However, many other parasequences reveal forced regressions during the progradational phases. This evidences that the progradational phases were driven by small, stepped, relative sea-level falls due to a tectonic activity related to the compressive Atlassic phase. This new paleoenvironmental interpretation suggests new elements for the palaeogeographic reconstruction of Northern Tunisia foredeep depozone during the Tortonian-Early Messinian. The base of the Kechabta Formation record the sedimentary response to regional marine transgression of the Mediterranean Sea from the East. This basin was an elongated shallow marine gulf parallel to the thrust front. The fluvio-deltaic systems of the paleo-Medjerda Rivers provided the bulk of the Kechabta siliciclastic sedimentary flux and extensive prograding delta are formed.
The Tunisian Dorsal backland is the Eastern Atlas side of maghrebides. Field data of Fahs area al... more The Tunisian Dorsal backland is the Eastern Atlas side of maghrebides. Field data of Fahs area allowed us to develop new interpretations and to characterize the main structural features of the studied devices (Jebel Rouas and Ruissate). Heritage of Zaghouan accident, Triassic salt movements and strike-direction of major synsedimentary faults are the principal causes and results of the skinned and superimposed geometric architecture, generated by the reversed extensional (Jurassic-Cretaceous) tectonics. The actual geometry of Jebel Rouas and Ruissate represents a fault propagation fold, affecting Jurassic and Cretaceous sets. The backland of this thrust fault defines an imbrications structures of Barremian series. Tectonic records activities show the existence of angular unconformities (Oligocene and Eocene series on the Cretaceous sets considered as bedrock), slumps, tectonic breccias and synsedimentary faults are all of them controlled by a deep major accident; N-S to NE-SW and NW-SE. Features of the study area are probably related first; to the blockage of Zaghouan thrust oriented NE-SW in the foreland; then, to the intense halokinetic activity, which facilitates the layers displacement acting as decollment level. The detailed structural and stratigraphic study of Fahs area and its neighbors shows the presence of an intense tangential tectonic during upper Miocene, affecting Meso-Cenozoic sets, because all the structures involved are sealed by Oligocene and Miocene thinned series. This is accentuated by the existence of different sets of decollment at different depths, which are represented by a displacement to the * Corresponding author. A. Arfaoui et al. 240 SE through the backland of the Tunisian Dorsal. We define these features as an imbrication and thrusting Out of sequence system.
The Structural Geology Contribution to the Africa-Eurasia Geology: Basement and Reservoir Structure, Ore Mineralisation and Tectonic Modelling, 2018
Morphotectonic analysis shows the effects of local uplift related to active reverse and strike-sl... more Morphotectonic analysis shows the effects of local uplift related to active reverse and strike-slip faults in Northern Tunisia. Furthermore, we find that the main reverse-sinistral NE-SW oriented faults like the Alia-Teboursouk fault are segmented by conjugate WNW-ESE active dextral faults. The dextral faults, namely the Dhkila and Oued Zarga faults, have cut the drainage basins, uplifting and displacing the middle segment of the Tine River basin. The main anomalies of the normalized steepness index (Ksn) coincide with regions uplifted by the fault system or associated folds. Furthermore, some of the anomalies depict the footwall of late Miocene normal faults that exhumed competent Cretaceous sediments.
The scarcity of shallow water, which is a delicate matter in southern Tunisia, is relatively comp... more The scarcity of shallow water, which is a delicate matter in southern Tunisia, is relatively compensated by groundwater resources. Indeed, the South contains 25% of water reserves of the country whom 10% are superficial water. The different hydrogeological studies show that the Zeuss-Koutine region is composed of several aquifer systems, which may be subdivided into two distinct levels; a superficial and a deep one. Such water resources show signs of localized overexploitation which has a serious effect on the change of the hydrosystem characteristics in this region. Recently, Tunisia proves to be very interested in the contribution of new technology in particular Geographic Information System (GIS) to resolve the problem of water resources deficit in Tunisia essentially in semi-arid southern part, in addition to the increased exploitation of groundwater resources, not renewable basically in last years. Hence, preserving water resources in the short and long term is a must. This fact might be achieved by the geographical information system (GIS). To respond to this object, detailed hydrological and hydrogeological studies are efficient, and a Geographic Relational Data Base Management System (RDBMS) by MERISE model was created in this study for organization of all these data in a structured way (method) and was easily exploitable under it. In addition, a lithostratigraphic correlation by the GIS is very important for understanding of the aquifer geometry and hydrodynamic interactions. The correlation among multi data shows a high degradation increasing from the South to the North (both quality and quantity of the Zeuss-Koutine groundwater). That is why another study of the water quality (salinity) and exploitation is considered crucial.
Abstract Tectonic inversion in the Bouhedma-Boudouaou Mountains was investigated through recent f... more Abstract Tectonic inversion in the Bouhedma-Boudouaou Mountains was investigated through recent field work and seismic lines interpretation calibrated with petroleum well data. Located to the Central-Southern Atlas of Tunisia, this area signed shortened intra-continental fold-and-thrust belts. Two dissymmetric anticlines characterize Bouhedma – Boudouaou major fold. These structures show a strong virgation respectively from E-W to NNE-SSW as a response to the interference between both tectonic inversion and tectonic inheritance. This complex geometry is driven by Mesozoic rifting, which marked an extensional inherited regime. A set of late Triassic-Early Jurassic E-W and NW-SE normal faults dipping respectively to the North and to the East seems to widely affect the overall geodynamic evolution of this domain. They result in major thickness changes across the hanging wall and the footwall blocks in response with the rifting activity. Tectonic inversion is inferred from convergence between African and European plates since late Cretaceous. During Serravalian - Tortonian event, NW-SE trending paroxysm led to: 1) folding of pre-inversion and syn-inversion strata, 2) reactivation of pre-existing normal faults to reverse ones and 3) orogeny of the main structures with NE-SW and E-W trending. The compressional feature still remains active during Quaternary event (Post-Villafranchian) with N-S trending compression. Contraction during inversion generates folding and internal deformation as well as Fault-Propagation-Fold and folding related strike.
Exploration of territories not previously analyzed by landslide experts provides interesting find... more Exploration of territories not previously analyzed by landslide experts provides interesting findings. The Chgega landslide, in northern Tunisia, represents a paradigmatic mass movement. It can be classified as a complex landslide, or more specifically as vast rock spreading that evolved into a block slide. It involves a great block of limestone—about 900 m long and 400 m wide—sliding over ductile clays and marls. The viscoplastic creep of the clays drives the landslide and creates, in its crown, a graben ~800 m long and ~120 m wide that breaks the summit of Chgega Mountain. Using Interferometric Synthetic Aperture Radar (InSAR) technologies, we demonstrate that this complex landslide is currently active and moreover shows progressive movement without clear episodic accelerations. The velocity of the limestone block is just above 2 mm/yr. The occurrence of gravity-induced joints indicates that the movement has an orientation towards 333° of azimuth on average, conditioned by the lan...
Exploration of territories not previously analyzed by landslide experts provides interesting find... more Exploration of territories not previously analyzed by landslide experts provides interesting findings. The Chgega landslide, in northern Tunisia, represents a paradigmatic mass movement. It can be classified as a complex landslide, or more specifically as vast rock spreading that evolved into a block slide. It involves a great block of limestone—about 900 m long and 400 m wide—sliding over ductile clays and marls. The viscoplastic creep of the clays drives the landslide and creates, in its crown, a graben ~800 m long and ~120 m wide that breaks the summit of Chgega Mountain. Using Interferometric Synthetic Aperture Radar (InSAR) technologies, we demonstrate that this complex landslide is currently active and moreover shows progressive movement without clear episodic accelerations. The velocity of the limestone block is just above 2 mm/yr. The occurrence of gravity-induced joints indicates that the movement has an orientation towards 333° of azimuth on average, conditioned by the lan...
The particularity of the Gafsa basin comes from the direction of belts structures that are NW-SE ... more 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 Tria...
Optical remote sensing was used to provide scientific information to support environmental manage... more Optical remote sensing was used to provide scientific information to support environmental management in the Gulf of Gabes located on the southeastern coast of Tunisia. This region is characterized by a shallow continental shelf with semi-diurnal tides. Since the early 1970s, industrial activity in this area may have contributed to the degradation of ecosystem biodiversity due to problems of eutrophication and the disappearance of benthic and planktonic species. Previous studies assessing the long term effects of anthropogenic and natural discharges on the Gulf of Gabes were based on regular seaborne measurements of total suspended matter, Secchi depth, turbidity, chlorophyll and temperature. However, these are often costly and difficult to obtain. The objective of this study is to carry out an optical remote sensing analysis with supporting in situ measurements of chlorophyll to monitor water quality and the impact of industrial discharges in the Gulf of Gabes. To start with, data ...
Sondeos petrolíferos realizados en la plataforma sahariana al sur de Túnez han puesto de manifies... more Sondeos petrolíferos realizados en la plataforma sahariana al sur de Túnez han puesto de manifiesto la existencia de materiales precámbricos y paleozoicos. Las litologías dominantes en el Paleozoico inferior son pizarras y areniscas, mientras que el Paleozoico ...
A stratigraphic study was carried out on the Jebel Boulahouajeb section (Lansarine Chain; Tebourb... more A stratigraphic study was carried out on the Jebel Boulahouajeb section (Lansarine Chain; Tebourba area, northern Tunisia) in order to establish a relatively detailed biostratigraphic framework of the Hauterivian pelagic deposits of the Tunisian trough. The limestone-marl alternations are represented by five limestone-dominated intervals, named calcareous bundles H1 to H5, separated by thick marly-dominated intervals. The well exposed Jebel Boulahouajeb section (873 m in thickness) is relatively continuous, rich in ammonoid macrofauna, and provides an ideal succession for this approach. Concerning the Hauterivian ammonoid zonal scheme, the following (sub-)zones have been identified: Acanthodiscus radiatus, Crioceratites loryi, Lyticoceras nodosoplicatum, Balearites balearis (with B.
Comptes Rendus de l'Académie des Sciences - Series IIA - Earth and Planetary Science, 1999
Slim-Shim& 1992). The l/50 000 geological map (Rouvier, 7988) of the studied area shows four lith... more Slim-Shim& 1992). The l/50 000 geological map (Rouvier, 7988) of the studied area shows four lithostratigraphic groups: marls and limestones, including Abiod Formation (Upper Cretaceous), El Haria Formation (Early Eocene), Metlaoui Formation (Middle Eocene) and Souar Formation (Middle Eocene to Early Oligocene); Note p&sent&e par Michel Durand-Delga.
The aim of this contribution is the interpretation of intracratonic chains in African plates, but... more 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 Africa and 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.
Optical remote sensing was used to provide scientific information to support environmental manage... more Optical remote sensing was used to provide scientific information to support environmental management in the Gulf of Gabes located on the southeastern coast of Tunisia. This region is characterized by a shallow continental shelf with semi-diurnal tides. Since the early 1970s, industrial activity in this area may have contributed to the degradation of ecosystem biodiversity due to problems of eutrophication and the disappearance of benthic and planktonic species. Previous studies assessing the long term effects of anthropogenic and natural discharges on the Gulf of Gabes were based on regular seaborne measurements of total suspended matter, Secchi depth, turbidity, chlorophyll and temperature. However, these are often costly and difficult to obtain. The objective of this study is to carry out an optical remote sensing analysis with supporting in situ measurements of chlorophyll to monitor water quality and the impact of industrial discharges in the Gulf of Gabes. To start with, data ...
Abstract The Kechabta Basin is part of the Tunisian Foreland Basin in front of the Numidian and T... more Abstract The Kechabta Basin is part of the Tunisian Foreland Basin in front of the Numidian and Tellian nappes. During the Tortonian, this basin records a strong subsidence rate due to flexural process, in front of the nappes. Contrary to previous interpretations, a sedimentological investigation of the thick Tortonian-Early Messinian Kechabta Formation (over 1300 m) reveals that this siliciclastic series corresponds to a complex deltaic shorelines deposit dominated by waves and influenced by tides. This formation is mainly made of a large number of high frequency, mudstone to sandy prograding parasequences representing repeated progradational phases of the coastal wedge. Facies successions within many of the parasequences show normal regressive trends. These parasequences present offshore grey-brown mudstone, followed by transition offshore sandy storm beds alternating with mudstone, then by shoreface sandstones bearing hummocky-cross stratification and wave ripples, then by foreshore facies or tidal flat facies. However, many other parasequences reveal forced regressions during the progradational phases. This evidences that the progradational phases were driven by small, stepped, relative sea-level falls due to a tectonic activity related to the compressive Atlassic phase. This new paleoenvironmental interpretation suggests new elements for the palaeogeographic reconstruction of Northern Tunisia foredeep depozone during the Tortonian-Early Messinian. The base of the Kechabta Formation record the sedimentary response to regional marine transgression of the Mediterranean Sea from the East. This basin was an elongated shallow marine gulf parallel to the thrust front. The fluvio-deltaic systems of the paleo-Medjerda Rivers provided the bulk of the Kechabta siliciclastic sedimentary flux and extensive prograding delta are formed.
The Tunisian Dorsal backland is the Eastern Atlas side of maghrebides. Field data of Fahs area al... more The Tunisian Dorsal backland is the Eastern Atlas side of maghrebides. Field data of Fahs area allowed us to develop new interpretations and to characterize the main structural features of the studied devices (Jebel Rouas and Ruissate). Heritage of Zaghouan accident, Triassic salt movements and strike-direction of major synsedimentary faults are the principal causes and results of the skinned and superimposed geometric architecture, generated by the reversed extensional (Jurassic-Cretaceous) tectonics. The actual geometry of Jebel Rouas and Ruissate represents a fault propagation fold, affecting Jurassic and Cretaceous sets. The backland of this thrust fault defines an imbrications structures of Barremian series. Tectonic records activities show the existence of angular unconformities (Oligocene and Eocene series on the Cretaceous sets considered as bedrock), slumps, tectonic breccias and synsedimentary faults are all of them controlled by a deep major accident; N-S to NE-SW and NW-SE. Features of the study area are probably related first; to the blockage of Zaghouan thrust oriented NE-SW in the foreland; then, to the intense halokinetic activity, which facilitates the layers displacement acting as decollment level. The detailed structural and stratigraphic study of Fahs area and its neighbors shows the presence of an intense tangential tectonic during upper Miocene, affecting Meso-Cenozoic sets, because all the structures involved are sealed by Oligocene and Miocene thinned series. This is accentuated by the existence of different sets of decollment at different depths, which are represented by a displacement to the * Corresponding author. A. Arfaoui et al. 240 SE through the backland of the Tunisian Dorsal. We define these features as an imbrication and thrusting Out of sequence system.
The Structural Geology Contribution to the Africa-Eurasia Geology: Basement and Reservoir Structure, Ore Mineralisation and Tectonic Modelling, 2018
Morphotectonic analysis shows the effects of local uplift related to active reverse and strike-sl... more Morphotectonic analysis shows the effects of local uplift related to active reverse and strike-slip faults in Northern Tunisia. Furthermore, we find that the main reverse-sinistral NE-SW oriented faults like the Alia-Teboursouk fault are segmented by conjugate WNW-ESE active dextral faults. The dextral faults, namely the Dhkila and Oued Zarga faults, have cut the drainage basins, uplifting and displacing the middle segment of the Tine River basin. The main anomalies of the normalized steepness index (Ksn) coincide with regions uplifted by the fault system or associated folds. Furthermore, some of the anomalies depict the footwall of late Miocene normal faults that exhumed competent Cretaceous sediments.
The scarcity of shallow water, which is a delicate matter in southern Tunisia, is relatively comp... more The scarcity of shallow water, which is a delicate matter in southern Tunisia, is relatively compensated by groundwater resources. Indeed, the South contains 25% of water reserves of the country whom 10% are superficial water. The different hydrogeological studies show that the Zeuss-Koutine region is composed of several aquifer systems, which may be subdivided into two distinct levels; a superficial and a deep one. Such water resources show signs of localized overexploitation which has a serious effect on the change of the hydrosystem characteristics in this region. Recently, Tunisia proves to be very interested in the contribution of new technology in particular Geographic Information System (GIS) to resolve the problem of water resources deficit in Tunisia essentially in semi-arid southern part, in addition to the increased exploitation of groundwater resources, not renewable basically in last years. Hence, preserving water resources in the short and long term is a must. This fact might be achieved by the geographical information system (GIS). To respond to this object, detailed hydrological and hydrogeological studies are efficient, and a Geographic Relational Data Base Management System (RDBMS) by MERISE model was created in this study for organization of all these data in a structured way (method) and was easily exploitable under it. In addition, a lithostratigraphic correlation by the GIS is very important for understanding of the aquifer geometry and hydrodynamic interactions. The correlation among multi data shows a high degradation increasing from the South to the North (both quality and quantity of the Zeuss-Koutine groundwater). That is why another study of the water quality (salinity) and exploitation is considered crucial.
Abstract Tectonic inversion in the Bouhedma-Boudouaou Mountains was investigated through recent f... more Abstract Tectonic inversion in the Bouhedma-Boudouaou Mountains was investigated through recent field work and seismic lines interpretation calibrated with petroleum well data. Located to the Central-Southern Atlas of Tunisia, this area signed shortened intra-continental fold-and-thrust belts. Two dissymmetric anticlines characterize Bouhedma – Boudouaou major fold. These structures show a strong virgation respectively from E-W to NNE-SSW as a response to the interference between both tectonic inversion and tectonic inheritance. This complex geometry is driven by Mesozoic rifting, which marked an extensional inherited regime. A set of late Triassic-Early Jurassic E-W and NW-SE normal faults dipping respectively to the North and to the East seems to widely affect the overall geodynamic evolution of this domain. They result in major thickness changes across the hanging wall and the footwall blocks in response with the rifting activity. Tectonic inversion is inferred from convergence between African and European plates since late Cretaceous. During Serravalian - Tortonian event, NW-SE trending paroxysm led to: 1) folding of pre-inversion and syn-inversion strata, 2) reactivation of pre-existing normal faults to reverse ones and 3) orogeny of the main structures with NE-SW and E-W trending. The compressional feature still remains active during Quaternary event (Post-Villafranchian) with N-S trending compression. Contraction during inversion generates folding and internal deformation as well as Fault-Propagation-Fold and folding related strike.
Exploration of territories not previously analyzed by landslide experts provides interesting find... more Exploration of territories not previously analyzed by landslide experts provides interesting findings. The Chgega landslide, in northern Tunisia, represents a paradigmatic mass movement. It can be classified as a complex landslide, or more specifically as vast rock spreading that evolved into a block slide. It involves a great block of limestone—about 900 m long and 400 m wide—sliding over ductile clays and marls. The viscoplastic creep of the clays drives the landslide and creates, in its crown, a graben ~800 m long and ~120 m wide that breaks the summit of Chgega Mountain. Using Interferometric Synthetic Aperture Radar (InSAR) technologies, we demonstrate that this complex landslide is currently active and moreover shows progressive movement without clear episodic accelerations. The velocity of the limestone block is just above 2 mm/yr. The occurrence of gravity-induced joints indicates that the movement has an orientation towards 333° of azimuth on average, conditioned by the lan...
Exploration of territories not previously analyzed by landslide experts provides interesting find... more Exploration of territories not previously analyzed by landslide experts provides interesting findings. The Chgega landslide, in northern Tunisia, represents a paradigmatic mass movement. It can be classified as a complex landslide, or more specifically as vast rock spreading that evolved into a block slide. It involves a great block of limestone—about 900 m long and 400 m wide—sliding over ductile clays and marls. The viscoplastic creep of the clays drives the landslide and creates, in its crown, a graben ~800 m long and ~120 m wide that breaks the summit of Chgega Mountain. Using Interferometric Synthetic Aperture Radar (InSAR) technologies, we demonstrate that this complex landslide is currently active and moreover shows progressive movement without clear episodic accelerations. The velocity of the limestone block is just above 2 mm/yr. The occurrence of gravity-induced joints indicates that the movement has an orientation towards 333° of azimuth on average, conditioned by the lan...
Uploads
Papers by Fouad Zargouni