Polyphasic evolution of the Jeffara basin in southern Tunisia, influence of halokinesis on the passive margin structuration in the Mesozoic and the Cenozoic

• Published in: Arabian journal of geosciences Vol. 11; no. 4; pp. 1 - 22
• Main Authors: Khouni, Radhouane, Arfaoui, Mohamed Sabri, Dridi, Soufiane, Zargouni, Fouad
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.02.2018; Springer Nature B.V
• Subjects: Agic 2017; Basins; Carbonates; Carboniferous; Cenozoic; Clay; Cretaceous; Diapirism; Earth and Environmental Science; Earth science; Earth Sciences; Evolution; Exhaustion; Fault lines; Fault zones; Faults; Geological faults; Geology of North Africa and Mediterranean regions; Graben; Jurassic; Limestone; Marl; Mesozoic; Miocene; Nuclei; Nucleus; Oil wells; Passive margins; Permian; Petroleum; Piercing; Plates (tectonics); Profiles; Rifting; Salts; Sandstone; Sedimentary rocks; Sedimentation; Sedimentation & deposition; Seismic analysis; Seismic surveys; Subsidence; Synclines; Triassic; Water wells; Well data; Jerba; Tunisia; Halokinesis; Subsidence; Geodynamics; Tunisia; Jeffara; Seismic data
• DOI: 10.1007/s12517-017-3363-8
• ISSN: 1866-7511

During the Mesozoic and Cenozoic rifting, the Pelagian Sea recorded the consequences of the African and European plate’s rapprochement. The interpretation of surface and subsurface data that is the 2D seismic reflection and petroleum well data show new ideas on the geodynamic evolution and halokinesis of the Jeffara basin during the Mesozoic and Cenozoic period. Seismic lines interpretations of the subsurface mainly reveal normal syn-sedimentary NW-SE faulting and where the Jeffara fault seems to be the major play. This syn-sedimentary faulting induced horst and graben structures materialized by major sedimentary sequences thicknesses as well as depths variations on the seismic profiles from the Jeffara fault zone overall towards the East of Jeffara basin. After the Hercynian event of the Permian - Carboniferous age, a general extension took place, which gave rise to the Tethyan opening. This extension has favored the individualization of the Jeffara basin in the South East of Tunisia, characterized by a structuring in Horst and Graben with a Permian carbonate subsidence. During the Triassic - Middle Jurassic period, the Jeffara basin is marked by a pronounced subsidence of essentially evaporate sedimentation accompanied by the birth of normal syn-sedimentary NW-SE faults following an NE-SW extension. This subsidence continuing during the Upper Jurassic period, the accentuation of which is towards the NE of the study zone at the Jerba and El Bibane sub-basin with a dominance of bioclastic limestone and dolomites sedimentation in the same extensive NE-SW direction, during this period, the Jeffara basin was characterized by a beginning of salt activity indicated by the appearance of salt nuclei at the base of the preexisting NW-SE normal faults. During the Lower Cretaceous, we are witnessing an individualization of salt complexes in the SE of the study area at Rass Ajil sub-basin, where this reactive diapirism has produced high zones and erosions in the crest above the salt bodies. During the mid Cretaceous period, the Zebbag formation, hatched by the Gattar carbonate bar, recorded a subsidence inversion phenomenon between the three sub-basins Jerba, El Bibane and Rass Ajil sub-basin, and showed the change of movement of the African plate relative to the European plate related to the opening of the North Atlantic and the beginning of the drift towards the North of Africa. This phenomenon is concretized towards the Upper Cretaceous, where we witness a strong subsidence towards the southeastern part of the study area at Rass Ajil sub-basin with sandstone, marl and clay sedimentation under a regional extensive regime and the individualization of high zones at Jerba sub-basin. The salt movements present an active aspect by piercing their cover and inducing rim synclines in the surroundings. The Cenozoic period is characterized by a strong subsidence of sandstone, clays and carbonates along the Jeffara basin, the salt activity shows a passive aspect at the beginning of this period which slows down and eventually stopped at the late Miocene period, thus indicating the probable exhaustion of the source of the salt material.