Les manifestations tectoniques synsédimentaires associées à la compression éocène en Tunisie : implications paléogéographiques et structurales sur la marge Nord-Africaine

Ghali, A. El; Ayed, Naceur; Bobier, Claude; Zargouni, Fouad; Krima, Anis

doi:10.1016/s1631-0713(03)00117-2

Cited by 55 publications

(30 citation statements)

References 9 publications

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“…This deformation is sealed by a late Maastrichtian unconformity (U1), which marks the initiation of a period of relative tectonic quiescence in this region as no significant syntectonic sedimentation is detected in the Paleocene and Eocene intervals. The only Eocene deformation observed in the study area is expressed by decametric fault propagation folds sealed by phosphate deposits as documented by El Ghali et al [2003] in the Metlaoui mine (Figure 11). Therefore, the major Eocene “Atlas event” described in the Algerian Atlas [ Laffitte , 1939; Bracène and Frizon de Lamotte , 2002; Benaouali ‐ Mebarek et al , 2006] or in eastern Tunisia (Gulf of Hammamet and adjacent Sahel coastal plain) [ Khomsi et al , 2009] did not apparently deform significantly the Gafsa basin and surrounding areas.…”

Section: Discussionmentioning

confidence: 87%

Structure, paleogeographic inheritance, and deformation history of the southern Atlas foreland fold and thrust belt of Tunisia

Said¹,

Baby²,

Chardon³

et al. 2011

Tectonics

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Structural analysis of the southern Tunisian Atlas was carried out using field observation, seismic interpretation, and cross section balancing. It shows a mix of thick‐skinned and thin‐skinned tectonics with lateral variations in regional structural geometry and amounts of shortening controlled by NW‐SE oblique ramps and tear faults. It confirms the role of the Late Triassic–Early Jurassic rifting inheritance in the structuring of the active foreland fold and thrust belt of the southern Tunisian Atlas, in particular in the development of NW‐SE oblique structures such as the Gafsa fault. The Late Triassic–Early Jurassic structural pattern is characterized by a family of first‐order NW‐SE trending normal faults dipping to the east and by second‐order E‐W trending normal faults limiting a complex system of grabens and horsts. These faults have been inverted during two contractional tectonic events. The first event occurred between the middle Turonian and the late Maastrichtian and can be correlated with the onset of the convergence between Africa and Eurasia. The second event corresponding to the principal shortening tectonic event in the southern Atlas started in the Serravalian‐Tortonian and is still active. During the Neogene, the southern Atlas foreland fold and thrust belt propagated on the evaporitic décollement level infilling the Late Triassic–Early Jurassic rift. The major Eocene “Atlas event,” described in hinterland domains and in eastern Tunisia, did not deform significantly the southern Tunisian Atlas, which corresponded in this period to a backbulge broad depozone.

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Section: Discussionmentioning

confidence: 87%

Structure, paleogeographic inheritance, and deformation history of the southern Atlas foreland fold and thrust belt of Tunisia

Said¹,

Baby²,

Chardon³

et al. 2011

Tectonics

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“…Only three compressive focal mechanisms appear in the blind thrust front that delimits southern Atlas and was apparently activated during the Pliocene‐Quaternary period [ Vially et al ., ]. On the southern side, the central Atlas graben is a paraseismic zone (Figure ) characterized by low seismicity (frequency and magnitude). Only a few earthquakes affecting the lower crust are associated with E‐W and N‐S major faults (Figures and ), inherited from the Cretaceous tectonic activity [ Ben Ayed , ] and reactivated in the Quaternary [ Philip et al ., ; Ben Ayed , ; El Ghali et al ., ]. This area with the deepest Moho and a thick and rigid continental crust [ Jallouli and Mickus , ] appears to have resisted to the seismogenic deformation.…”

Section: Tectonic Regime and Focal Depth Distribution In Tunisiamentioning

confidence: 99%

Spatial variation of present-day stress field and tectonic regime in Tunisia and surroundings from formal inversion of focal mechanisms: Geodynamic implications for central Mediterranean

Soumaya

Ayed²,

Delvaux

et al. 2015

Tectonics

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We compiled 123 focal mechanisms from various sources for Tunisia and adjacent regions up to Sicily, to image the current stress field in the Maghrebides chain (from Tunisia to Sicily) and its foreland. Stress inversion of all the available data provides a first-order stress field with a N150°E horizontal compression (S Hmax ) and a transpressional tectonic regime, but the obtained stress tensor poorly fit to the data set. We separated them into regional subsets (boxes) in function of their geographical proximity, kinematic regime, homogeneity of kinematic orientations, and tectonic setting. Their respective inversion evidences second-and third-order spatial variations in tectonic regime and horizontal stress directions. The stress field gradually changes from compression in the Maghrebides thrust belt to transpression and strike slip in the Atlassic and Pelagian foreland, respectively, where preexisting NW-SE to E-W deep faults system are reactivated. This spatial variation of the sismotectonic stress field and tectonic regime is consistent with the neotectonic stress field determined by others from fault slip data. The major Slab Transfer Edge Propagator faults (i.e., North-South Axis-Hammamet relay and Malte Escarpment), which laterally delimit the subducting slabs, play an active role in second-and third-order lateral variations of the tectonic regime and stress field orientations over the Tunisian/Sicilian domain. The past and current tectonic deformations and kinematics of the central Mediterranean are subordinately guided by the plate convergence (i.e., Africa-Eurasia), controlled or influenced by lateral slab migration/segmentation and by deep dynamics such as lithosphere-mantle interaction.

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“…This syn-sedimentary structure, well expressed during the Upper Eocene, fossilized the Pyrenean phase of folding (Yaïch 1984). This phase continued until the Upper Eocene (Morelli 1976;Letouzey and Trémolières 1980;Haller 1983;El Ghali et al 2003;Mzali and Zouari 2006), with a constraint σ 1 oriented NW-SE to NS. During this period, the N120°faults are reactivated in dextral shears; EW faults have a normal component and NE-SW faults have a reverse component, whereas NE-SW folds are outlined and the raise of the Triassic deposits is emphasized by listric faults (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Isocontours in TWT (ms) are given using the color bar values with an equidistance of 100 ms. P5, P7-P9: oil wells for correlations, F1-F6: faults, L1-L4: seismic lines location. G graben, H horst Ghali et al 2003). At the Middle to Upper Cretaceous (Albian-Lower Campanian), the tectonic mode is dextral transtensive (Fig.…”

Section: Discussionmentioning

confidence: 99%

Seismic and well log post-Cretaceous reservoir correlations in the Sahel, east Tunisia

et al. 2015

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International audienceThe eastern part of Tunisia is made up of the Atlasic chain foreland, a domain connected to a continental crust which thins northeastward. It is limited to the west and northwest by the corridor of the NS axis faults and by the Zaghouan fault which separates it from the Atlasic domain and trends toward the Pelagian Sea eastwards. It is regarded as a stable zone. The signs of the main events which generated the Atlasic structures are hidden under a thick Plio-Quaternary cover. From surface observations, microtectonic measurements, and lithostratigraphic sections and logs, including those of oil well log data and seismic profiles onshore and offshore, one notes (i) an in-depth and lateral variation of the lithostratigraphic series and (ii) a considerably faulted area at subsurface characterized by a complex structural evolution and shears associated with basins. Such variations are controlled by tectonics and eustatism. The eastern platform is affected only by N45° oriented folds, often accompanied by reverse faults and associated with N90–110° dextral and N160–180° sinistral shears. It corresponds to a tectonic foreland domain representing a folded and sheared deformation zone. The tectonic deformations recognized by seismic data only affect narrow corridors, lengthened and oriented according to three major directions: N45°, N100–120°, and N160–180°. These zones, mobile at several geological periods and tectonically complex, delimit large sectors which have undergone minimal deformation or none at all. Well developed in the Sahel, the reservoirs are carbonated and fractured types such as the limestones of Abiod, Metlaoui, Souar and Chérahil, Aïn Grab, and the Oum Dhouil group. Structural traps for the accumulation of hydrocarbons were formed following these Atlasic compression and folding phases. The deposit of thick argillaceous series during the Eocene (Souar and Chérahil) and during the Miocene (Oum Dhouil) constitutes good continuous covers which sealed the folded and faulted reservoir structures. The seismic profiles show traps which are associated with folded and closure structures by faults and stratigraphic traps through facies changes. The structural inversions and the thrust tectonics in eastern Tunisia play a significant role in the structuring of the cover and also in the evolution of the oil system emplacement. The reservoirs are supplied by bed rocks of the Cretaceous (Bahloul Formation) and the Eocene (Metlaoui Formation)

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Les manifestations tectoniques synsédimentaires associées à la compression éocène en Tunisie : implications paléogéographiques et structurales sur la marge Nord-Africaine

Cited by 55 publications

References 9 publications

Structure, paleogeographic inheritance, and deformation history of the southern Atlas foreland fold and thrust belt of Tunisia

Structure, paleogeographic inheritance, and deformation history of the southern Atlas foreland fold and thrust belt of Tunisia

Spatial variation of present-day stress field and tectonic regime in Tunisia and surroundings from formal inversion of focal mechanisms: Geodynamic implications for central Mediterranean

Seismic and well log post-Cretaceous reservoir correlations in the Sahel, east Tunisia

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