| 1. |
- Amri, Zayneb, et al.
(author)
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Mechanical relationship between strike-slip faulting and salt tectonics in the Northern Tunisian Atlas : The Bir-El-Afou salt structure
- 2022
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In: Journal of Structural Geology. - : Elsevier. - 0191-8141 .- 1873-1201. ; 154
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Journal article (peer-reviewed)abstract
- Wide variety of salt structures -from typical diapirs to large allochthonous salt sheets- are recognized in the Northern Tunisian Atlas. In this study, we present for the first time the presence of a diapiric structure, Bir-ElAfou Salt Structure (BEASS), which has formed in response to strike-slip tectonics. Structural mapping, mesoscale field observations, fault kinematic analysis, and interpretation of gravity data are used to interpret BEASS, which is currently associated with a restraining bend. The present-day NNE- trending restraining stepover is formed as a result of E-W dextral fault system. We assume that the restraining stepover is a product of the inversion of a pre-existing pull-apart basin that formed during the Cretaceous South Tethyan extension. Tectono-sedimentary relationship is used to argue for an early Cretaceous NW-SE regional extension and local transtension. During the opening of the pull-apart basin, salt movement took place in the southwestern corner of the basin which must have thinned due to its extension facilitating diapiric emplacement. Diapir growth during Aptian was followed by brief salt flow from the diapir crest towards the basin forming a salt sheet. A period of Tertiary contraction resulted in the inversion of the pull-apart basin and consequently, squeezing of BEASS.
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| 2. |
- Masrouhi, Amara, et al.
(author)
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Submarine allochthonous salt sheets : Gravity-driven deformation of North African Cretaceous passive margin in Tunisia - Bled Dogra case study and nearby salt structures
- 2014
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In: Journal of African Earth Sciences. - : Elsevier BV. - 1464-343X. ; 97, s. 125-142
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Journal article (peer-reviewed)abstract
- We used structural, stratigraphic and sedimentologic data, together with a comparison of nearby structures and a Bouguer gravity map, to evaluate the evolution of the Bled Dogra salt structure (northern Tunisia) during the Cretaceous. Triassic salt sheets are recognized in the northwestern region of the Tunisian Atlas. These salt sheets are the result of Cretaceous thick and/or thin-skinned extension along the south Tethyan margin. The Bled Dogra salt structure is one of these submarine allochthonous salt sheets, which was emplaced during the Early Cretaceous. The geologic framework, during this period, produces conditions for a predominantly gravity-driven deformation: extension has produced space for the salt to rise; vigorous differential sedimentation created differential loading that resulted in the emplacement and extrusion of a large volume of Triassic salt and formation of large submarine salt sheets. Geologic field data suggest an interlayered Triassic salt sheet within Albian sequences. Salt was extruded at the sea floor during the Early-Middle Albian and was initially buried by Middle-Late Albian strata. The Coniacian corresponds to a second transgressive cover onto the salt sheet after the gliding of the first salt cover (Late Albian-Turonian). In addition, this northwest Tunisian area exposes evidences for salt flow and abundant slump features at the base of a northward facing submarine slope, which was probably dominant from the Early Cretaceous to Santonian. Two gravity deformation processes are recognized: gravity gliding and gravity spreading. Acting concurrently, these two processes appear indistinguishable in this geologic context. Like the present-day salt-involved passive margins - such as the northern Gulf of Mexico, the Atlantic margin of Morocco, the Brazilian Santos basin, the Angola margin, Cadiz in western Iberia, and the Red Sea - the North African Cretaceous passive margin in Tunisia provides evidences that deformation in a passive-margin salt basin is predominantly gravity-driven deformation.
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| 3. |
- Masrouhi, Amara, et al.
(author)
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The evolution of the Lansarine-Baouala salt canopy in the North African Cretaceous passive margin in Tunisia
- 2013
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In: Geological Magazine. - 0016-7568 .- 1469-5081. ; 150:5, s. 835-861
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Journal article (peer-reviewed)abstract
- Detailed geological mapping, dating, and gravimetric and seismic data are used to interpret the Lansarine-Baouala salt structure (North Tunisia) as a salt canopy emplaced during the Cretaceous Period. The extensional tectonic regime related to the Cretaceous continental margin offered at least two factors that encouraged buried Triassic salt to extrude onto the sea floor and flow downslope: (i) extension induced normal faults that provided routes to the surface, and led to the formation of submarine slopes along which salt could flow; (ii) this structural setting led to differential sedimentation and consequently differential loading as a mechanism for salt movement. The present 40-km-long Lansarine-Baouala salt structure with its unique mass of allochthonous Triassic salt at surface was fed from at least four stems. The salt structure is recognized as one of the few examples worldwide of a subaerial salt canopy due to the coalescence of submarine sheets of Triassic salt extruded in Cretaceous times.
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