A 122 cm-long core was taken in the El-Guettiate Sebkha of Skhira (southeastern part of Tunisia) ... more A 122 cm-long core was taken in the El-Guettiate Sebkha of Skhira (southeastern part of Tunisia) in order to investigate the recent palaeoenvironmental evolution of this region. The quantitative and qualitative analysis of ostracod and benthic foraminifera assemblages coupled with a correspondence analysis allows the reconstruction of palaeoenvironmental changes during the Holocene in this area. Four typical associations of ostracods (open marine, coastal marine, lagoonal and estuarine brackish) and two associations of benthic foraminifera (coastal and lagoonal) were distinguished. The onset of restricted lagoonal environments linked to the building-up of sand spit led to the onset of restricted lagoon and brackish environment at cal. 5408 years BP. The Shannon and equitability index of diversity were used to decipher the structural variations of the populations of ostracods and benthic foraminifera along the sampled core. We note a reduction in the Shannon index from the bottom to the top, which indicates a progressive isolation of the biotope. The open lagoonal episode is characterized by high values of diversity. During restricted lagoonal episodes the Shannon and equitability index are reduced. The correspondence analysis reveals an environmental gradient related to the marine influence. It shows an antagonism between the widely opened estuarian lagoonal species and those of restricted lagoon. The less opened estuarian lagoonal taxa occupy an intermediate position. Based on these evidences, microfauna carried out in the El-Guettiate Sebkha allows us to recognize four phases beginning with a widely opened estuarian lagoon (ca. cal. 7460 years PB), followed by a restricted lagoon (ca. cal. 5408 years BP) and finally a brackish lagoon evolving towards the present-day sebkha environment. The opened estuarine lagoon is characterized by high values of species richness and diversity indices.
Travaux et Documents des Laboratoires de Géologie de Lyon, 2002
Kilani Fatma, Mehdi Dorra, Kamoun Fékri, Peybernès Bernard. Associations palynologiques et microp... more Kilani Fatma, Mehdi Dorra, Kamoun Fékri, Peybernès Bernard. Associations palynologiques et micropaléontologiques dans le Trias du Sud et du centre de la Tunisie. In: Documents des Laboratoires de Géologie, Lyon, n°156, 2002. STRATI 2002. 3ème congrès français de stratigraphie. Lyon, 8-10 juillet 2002. pp. 140-141
Résumé/Abstract Within the ten depositional sequences recently identified in the Triassic series ... more Résumé/Abstract Within the ten depositional sequences recently identified in the Triassic series from Far-South of Tunisia (Djeffara and North Dahar), carbonate transgressive systems tracts of five of them contain assemblages of benthonic Foraminifera allowing ...
This study represents a contribution to the biostratigraphic characterization of the Gulf of Gabe... more This study represents a contribution to the biostratigraphic characterization of the Gulf of Gabes Triassic series. Diverse andwell preserved palynological assemblages from the Djerba Melita 1 (DJM1)well in the Djerba Island (Gulf ofGabes, Southern Tunisia) are here presented and discussed. A Carnian microflora is recorded in the Triassic portion of the drilled succession. The co-occurrence of Ladinian-lower Carnian taxa in association with typical Carnian elements allows to refer the microflora to the lower part of the Duplicisporites continuus palynological assemblage (late Julian, Austrotrachyceras austriacus Subzone). A semi-quantitative analysis of the assemblages also seems to document the occurrence, in the middle-upper part (units 3 and 4) of DJM1 well of the Aulisporites-Aratrisporites Acme Zone, an ammonoid-calibrated palynological event occurring in several European successions, referring to the late Julian/early Tuvalian. The occurrence of this acme zone in Southern Tuni...
<p>New field investigations along the East Tunisian coastline reveal sedime... more <p>New field investigations along the East Tunisian coastline reveal sedimentary deposits and damaged localities that may account for a catastrophic event during late Holocene. North of Sfax - Thyna city (at Henchir El Majdoul site) ~3.4 m high cliff coastal marine and alluvial terraces show a 20 to 50-cm-thick chaotic layer with sandy coarse gravels mixed with limestone beach-rocks, reworked blocks, broken shells of marine and lagoon gastropods and lamellibranch mollusks, organic matter, and Roman pottery. The chaotic layer truncates a succession of sandy-silty paleosol, covers Roman settlements and is overlain by fire remains and a relatively thin (~10 cm) sandy-silty aeolian unit and ~1-m-thick alluvial deposits. Charcoal samples collected at 10 cm below and 4 cm above the catastrophic deposits provide radiocarbon dating that brackets a catastrophic event between 286 and 370 CE (2s). Beside the damaged Roman site of Thyna, other localities of the east Tunisian coastline such as Neapolis (Nabeul) near Tunis, Hadrumete (Sousse), Meninx-town in Girba (Djerba), Wadi Ennouili (Gulf of Gabes), and Sabratha (in Libya) experienced major damage and abandonment of sites in Fifth century. The extent of damage from northern Libya to northern Tunisia at the Fourth century and radiocarbon dating, added to the 2.6 m thick turbidite deposits west of Malta correlate with the major tsunamigenic earthquake of 21 July 365 (Mw ~ 8) in west Crete (Greece). Numerical modelling of the tsunami caused by an earthquake in the Hellenic Arc subduction zone suggests more than 3.5 m high tsunami waves propagation affecting the Tunisia coastline, resulting in a run-up consistent with the stratigraphic evidence presented here. The catastrophic deposits, offshore-onshore correlations, archeological damage and modelling of tsunami waves suggest a new, higher-resolution, assessment of the tsunami hazard leading to a better estimate of tsunami risk on the eastern coast of Tunisia.</p>
Marginal-marine to non-marine ostracod assemblages from the Bajocian (Mid-Jurassic) of southern T... more Marginal-marine to non-marine ostracod assemblages from the Bajocian (Mid-Jurassic) of southern Tunisia, precisely from the Krachoua Formation at the Kef El Anneba section near the Beni Kheddache area, are here described and tested for their utility to improve the stratigraphic accuracy and palaeoenvironmental reconstructions. This particular microfauna consists of 11 species belonging to 6 genera and represents 2 distinct types of species-rich assemblages from this time interval, allowing the interpretation of the depositional setting of the fossiliferous horizon from which the samples derive. The first ostracod assemblage is mainly composed of the brackish to shallow marine species Fastigatocythere sp. Mette, 1995; Vernoniella aff. V. bajociana Bate, 1965b; Paracypris sp. A, Paracypris sp. B, Fabanella sarda Malz et al., 1985; Marslatourella aff. M. bathonica Andreu, 1999; and Fabanella aff. F. bathonica Oertli, 1957. This ostracod biofacies reflects marginal marine (shallow platf...
Patterns and Mechanisms of Climate, Paleoclimate and Paleoenvironmental Changes from Low-Latitude Regions, 2019
The quantitative study of foraminiferal associations coupled with geochemical and sedimentologica... more The quantitative study of foraminiferal associations coupled with geochemical and sedimentological proxies, of a 94-cm sediment core from Korba lagoon (Cap Bon, Tunisia), enabled us to better understand the dynamics of depositional environments and identify different stages of evolution of the lagoon. Three major periods were identified. The first revealed high abundance of foraminifera dominated by lagoonal taxa associated with high TOC, TIC and Ca contents. These parameters marked the settlement of a closed lagoon separated from the open ocean by a sandy bar with high foraminiferal productivity in fine sediments. The second period showed the development of estuarine foraminifera coupled with the appearance of charophyte oogonia in addition to planktonic foraminifera, high Ti and Fe concentrations and dominant coarse fraction. These parameters are indicative of an open lagoon environment with the fluvial inputs. The disappearance of charophyte oogonia and planktonic foraminifera co...
Patterns and Mechanisms of Climate, Paleoclimate and Paleoenvironmental Changes from Low-Latitude Regions, 2019
Several cores retrieved from Ras Younga Sebkha, (Hachichina coast, Gulf of Gabes), are subjected ... more Several cores retrieved from Ras Younga Sebkha, (Hachichina coast, Gulf of Gabes), are subjected to a micropalaeontological and sedimentological study. The analysis of ostracods and foraminifera coupled with statistical approach (Correspondence analysis) are used in order to reconstruct the evolution of Holocene environment related to climatic and hydrodynamic forcing. The foraminifera and ostracods association present in the sediments core, allowed us to identify the different steps of the genesis of the Sebkha Ras Younga. Four major steps were distinguished: (i) the first one, corresponding to an estuarine lagoon, is characterized by the dominance of brackish ostracods association and reduced values of the diversity index (H) and (E); (ii) the second one, marked by the enrichment of marine, lagoonal, and shallow water ostracods and shallow water foraminifera and high values of (H) and (E) index, indicate the settlement of an opened lagoon toward 5105 a BP; (iii) the enhancement of...
American Scientific Research Journal for Engineering, Technology, and Sciences, 2017
According to the previous works, the addition of Tunisian phosphogypsum and cement to the clayey ... more According to the previous works, the addition of Tunisian phosphogypsum and cement to the clayey soils is able to improve the geotechnical properties of these soils. This addition reduces the swelling problems by making the soil more resistant to water. The degree of success of such a treatment remains dependent on several parameters such as particle size, plasticity, and the chemical and mineralogical composition of soils and the dosage of hydraulic binders. The experimental approach adopted within the framework of this study was oriented towards the characterization of the behavior of three different soil samples in the presence of phosphogypsum and cement at different proportions. To observe this effect, some geotechnical tests were performed such as the Proctor test and the CBR test. The results have shown the improvement in the maximum dry unit weight and the optimum water content depends on the quality of the soil (% clay fraction). The CBR index was influenced by this additio...
In Northwestern Tunisia, close to El Kef, the large outcropping surfaces of Triassic rocks are lo... more In Northwestern Tunisia, close to El Kef, the large outcropping surfaces of Triassic rocks are located between two sedimentary contacts, underlined by glauconitic conglomerates, which are filled with insoluble Triassic pebbles. In the Kt ed Dalaa, the Triassic rocks overlie conformably, sometimes in angular disconformity, a well-dated anticlinal built by a marly and calcareous-marly Lower Albian, in normal sequence according to its sedimentary features. In the area of Bled el Mzira they are covered conformably by a thick sequence beginning with Middle Albian planktonic beds. This setting, interpreted also in the nearby Dj. Ouenza and Ladjebel areas of easternmost Algeria, as a sub-marine «salt-glacier», allows simple explanation of: the existence of Miocene synclines directly and conformably overlying only the Triassic rocks, and the recent concept of «diapirs without surface salt»
Résumé/Abstract La série jurassique fossilifère (intervalle Toarcien-Oxfordien) affleurant en Tun... more Résumé/Abstract La série jurassique fossilifère (intervalle Toarcien-Oxfordien) affleurant en Tunisie dans l'Axe NS est ici subdivisée en 18 séquences de dépôt, étalonnées sur les biochronozones d'Ammonites subméditerranéennes ou téthysiennes. Certaines de ces ...
A 122 cm-long core was taken in the El-Guettiate Sebkha of Skhira (southeastern part of Tunisia) ... more A 122 cm-long core was taken in the El-Guettiate Sebkha of Skhira (southeastern part of Tunisia) in order to investigate the recent palaeoenvironmental evolution of this region. The quantitative and qualitative analysis of ostracod and benthic foraminifera assemblages coupled with a correspondence analysis allows the reconstruction of palaeoenvironmental changes during the Holocene in this area. Four typical associations of ostracods (open marine, coastal marine, lagoonal and estuarine brackish) and two associations of benthic foraminifera (coastal and lagoonal) were distinguished. The onset of restricted lagoonal environments linked to the building-up of sand spit led to the onset of restricted lagoon and brackish environment at cal. 5408 years BP. The Shannon and equitability index of diversity were used to decipher the structural variations of the populations of ostracods and benthic foraminifera along the sampled core. We note a reduction in the Shannon index from the bottom to the top, which indicates a progressive isolation of the biotope. The open lagoonal episode is characterized by high values of diversity. During restricted lagoonal episodes the Shannon and equitability index are reduced. The correspondence analysis reveals an environmental gradient related to the marine influence. It shows an antagonism between the widely opened estuarian lagoonal species and those of restricted lagoon. The less opened estuarian lagoonal taxa occupy an intermediate position. Based on these evidences, microfauna carried out in the El-Guettiate Sebkha allows us to recognize four phases beginning with a widely opened estuarian lagoon (ca. cal. 7460 years PB), followed by a restricted lagoon (ca. cal. 5408 years BP) and finally a brackish lagoon evolving towards the present-day sebkha environment. The opened estuarine lagoon is characterized by high values of species richness and diversity indices.
Travaux et Documents des Laboratoires de Géologie de Lyon, 2002
Kilani Fatma, Mehdi Dorra, Kamoun Fékri, Peybernès Bernard. Associations palynologiques et microp... more Kilani Fatma, Mehdi Dorra, Kamoun Fékri, Peybernès Bernard. Associations palynologiques et micropaléontologiques dans le Trias du Sud et du centre de la Tunisie. In: Documents des Laboratoires de Géologie, Lyon, n°156, 2002. STRATI 2002. 3ème congrès français de stratigraphie. Lyon, 8-10 juillet 2002. pp. 140-141
Résumé/Abstract Within the ten depositional sequences recently identified in the Triassic series ... more Résumé/Abstract Within the ten depositional sequences recently identified in the Triassic series from Far-South of Tunisia (Djeffara and North Dahar), carbonate transgressive systems tracts of five of them contain assemblages of benthonic Foraminifera allowing ...
This study represents a contribution to the biostratigraphic characterization of the Gulf of Gabe... more This study represents a contribution to the biostratigraphic characterization of the Gulf of Gabes Triassic series. Diverse andwell preserved palynological assemblages from the Djerba Melita 1 (DJM1)well in the Djerba Island (Gulf ofGabes, Southern Tunisia) are here presented and discussed. A Carnian microflora is recorded in the Triassic portion of the drilled succession. The co-occurrence of Ladinian-lower Carnian taxa in association with typical Carnian elements allows to refer the microflora to the lower part of the Duplicisporites continuus palynological assemblage (late Julian, Austrotrachyceras austriacus Subzone). A semi-quantitative analysis of the assemblages also seems to document the occurrence, in the middle-upper part (units 3 and 4) of DJM1 well of the Aulisporites-Aratrisporites Acme Zone, an ammonoid-calibrated palynological event occurring in several European successions, referring to the late Julian/early Tuvalian. The occurrence of this acme zone in Southern Tuni...
<p>New field investigations along the East Tunisian coastline reveal sedime... more <p>New field investigations along the East Tunisian coastline reveal sedimentary deposits and damaged localities that may account for a catastrophic event during late Holocene. North of Sfax - Thyna city (at Henchir El Majdoul site) ~3.4 m high cliff coastal marine and alluvial terraces show a 20 to 50-cm-thick chaotic layer with sandy coarse gravels mixed with limestone beach-rocks, reworked blocks, broken shells of marine and lagoon gastropods and lamellibranch mollusks, organic matter, and Roman pottery. The chaotic layer truncates a succession of sandy-silty paleosol, covers Roman settlements and is overlain by fire remains and a relatively thin (~10 cm) sandy-silty aeolian unit and ~1-m-thick alluvial deposits. Charcoal samples collected at 10 cm below and 4 cm above the catastrophic deposits provide radiocarbon dating that brackets a catastrophic event between 286 and 370 CE (2s). Beside the damaged Roman site of Thyna, other localities of the east Tunisian coastline such as Neapolis (Nabeul) near Tunis, Hadrumete (Sousse), Meninx-town in Girba (Djerba), Wadi Ennouili (Gulf of Gabes), and Sabratha (in Libya) experienced major damage and abandonment of sites in Fifth century. The extent of damage from northern Libya to northern Tunisia at the Fourth century and radiocarbon dating, added to the 2.6 m thick turbidite deposits west of Malta correlate with the major tsunamigenic earthquake of 21 July 365 (Mw ~ 8) in west Crete (Greece). Numerical modelling of the tsunami caused by an earthquake in the Hellenic Arc subduction zone suggests more than 3.5 m high tsunami waves propagation affecting the Tunisia coastline, resulting in a run-up consistent with the stratigraphic evidence presented here. The catastrophic deposits, offshore-onshore correlations, archeological damage and modelling of tsunami waves suggest a new, higher-resolution, assessment of the tsunami hazard leading to a better estimate of tsunami risk on the eastern coast of Tunisia.</p>
Marginal-marine to non-marine ostracod assemblages from the Bajocian (Mid-Jurassic) of southern T... more Marginal-marine to non-marine ostracod assemblages from the Bajocian (Mid-Jurassic) of southern Tunisia, precisely from the Krachoua Formation at the Kef El Anneba section near the Beni Kheddache area, are here described and tested for their utility to improve the stratigraphic accuracy and palaeoenvironmental reconstructions. This particular microfauna consists of 11 species belonging to 6 genera and represents 2 distinct types of species-rich assemblages from this time interval, allowing the interpretation of the depositional setting of the fossiliferous horizon from which the samples derive. The first ostracod assemblage is mainly composed of the brackish to shallow marine species Fastigatocythere sp. Mette, 1995; Vernoniella aff. V. bajociana Bate, 1965b; Paracypris sp. A, Paracypris sp. B, Fabanella sarda Malz et al., 1985; Marslatourella aff. M. bathonica Andreu, 1999; and Fabanella aff. F. bathonica Oertli, 1957. This ostracod biofacies reflects marginal marine (shallow platf...
Patterns and Mechanisms of Climate, Paleoclimate and Paleoenvironmental Changes from Low-Latitude Regions, 2019
The quantitative study of foraminiferal associations coupled with geochemical and sedimentologica... more The quantitative study of foraminiferal associations coupled with geochemical and sedimentological proxies, of a 94-cm sediment core from Korba lagoon (Cap Bon, Tunisia), enabled us to better understand the dynamics of depositional environments and identify different stages of evolution of the lagoon. Three major periods were identified. The first revealed high abundance of foraminifera dominated by lagoonal taxa associated with high TOC, TIC and Ca contents. These parameters marked the settlement of a closed lagoon separated from the open ocean by a sandy bar with high foraminiferal productivity in fine sediments. The second period showed the development of estuarine foraminifera coupled with the appearance of charophyte oogonia in addition to planktonic foraminifera, high Ti and Fe concentrations and dominant coarse fraction. These parameters are indicative of an open lagoon environment with the fluvial inputs. The disappearance of charophyte oogonia and planktonic foraminifera co...
Patterns and Mechanisms of Climate, Paleoclimate and Paleoenvironmental Changes from Low-Latitude Regions, 2019
Several cores retrieved from Ras Younga Sebkha, (Hachichina coast, Gulf of Gabes), are subjected ... more Several cores retrieved from Ras Younga Sebkha, (Hachichina coast, Gulf of Gabes), are subjected to a micropalaeontological and sedimentological study. The analysis of ostracods and foraminifera coupled with statistical approach (Correspondence analysis) are used in order to reconstruct the evolution of Holocene environment related to climatic and hydrodynamic forcing. The foraminifera and ostracods association present in the sediments core, allowed us to identify the different steps of the genesis of the Sebkha Ras Younga. Four major steps were distinguished: (i) the first one, corresponding to an estuarine lagoon, is characterized by the dominance of brackish ostracods association and reduced values of the diversity index (H) and (E); (ii) the second one, marked by the enrichment of marine, lagoonal, and shallow water ostracods and shallow water foraminifera and high values of (H) and (E) index, indicate the settlement of an opened lagoon toward 5105 a BP; (iii) the enhancement of...
American Scientific Research Journal for Engineering, Technology, and Sciences, 2017
According to the previous works, the addition of Tunisian phosphogypsum and cement to the clayey ... more According to the previous works, the addition of Tunisian phosphogypsum and cement to the clayey soils is able to improve the geotechnical properties of these soils. This addition reduces the swelling problems by making the soil more resistant to water. The degree of success of such a treatment remains dependent on several parameters such as particle size, plasticity, and the chemical and mineralogical composition of soils and the dosage of hydraulic binders. The experimental approach adopted within the framework of this study was oriented towards the characterization of the behavior of three different soil samples in the presence of phosphogypsum and cement at different proportions. To observe this effect, some geotechnical tests were performed such as the Proctor test and the CBR test. The results have shown the improvement in the maximum dry unit weight and the optimum water content depends on the quality of the soil (% clay fraction). The CBR index was influenced by this additio...
In Northwestern Tunisia, close to El Kef, the large outcropping surfaces of Triassic rocks are lo... more In Northwestern Tunisia, close to El Kef, the large outcropping surfaces of Triassic rocks are located between two sedimentary contacts, underlined by glauconitic conglomerates, which are filled with insoluble Triassic pebbles. In the Kt ed Dalaa, the Triassic rocks overlie conformably, sometimes in angular disconformity, a well-dated anticlinal built by a marly and calcareous-marly Lower Albian, in normal sequence according to its sedimentary features. In the area of Bled el Mzira they are covered conformably by a thick sequence beginning with Middle Albian planktonic beds. This setting, interpreted also in the nearby Dj. Ouenza and Ladjebel areas of easternmost Algeria, as a sub-marine «salt-glacier», allows simple explanation of: the existence of Miocene synclines directly and conformably overlying only the Triassic rocks, and the recent concept of «diapirs without surface salt»
Résumé/Abstract La série jurassique fossilifère (intervalle Toarcien-Oxfordien) affleurant en Tun... more Résumé/Abstract La série jurassique fossilifère (intervalle Toarcien-Oxfordien) affleurant en Tunisie dans l'Axe NS est ici subdivisée en 18 séquences de dépôt, étalonnées sur les biochronozones d'Ammonites subméditerranéennes ou téthysiennes. Certaines de ces ...
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