Basement structure of southern Tunisia as determined from the analysis of gravity data: implications for petroleum exploration

Abstract

Gravity data were analysed in the Ghadames Basin and surrounding regions in southern Tunisia in order to determine the basement structure of the region and its relationship to petroleum exploration in relatively unexplored basins. The analysis included the construction of regional Bouguer gravity anomaly and horizontal gravity gradient maps. These maps indicate that the Ghadames Basin is not a simple sag basin but consists of a series of sub-basins and uplifts. The northern boundary of the basin which we call the Telemzan–Ghadames transition zone is marked by a NE-trending high amplitude gravity gradient anomaly which decreases in amplitude toward the east and breaks into a series of north–south- and east–west-trending anomalies implying a more structurally complex region. When the known petroleum fields are overlain on to the gravity gradient anomaly maps, the fields mostly occur along or next to linear alignments of horizontal gravity gradient maxima. We interpret the correlation of the petroleum fields and horizontal gravity gradient maxima to indicate that the basement was involved in forming the petroleum traps. This study illustrates that a regional gravity analysis can be useful in determining where additional exploration can be applied in relatively unexplored basins.

The Southern Atlas Front in Tunisia and its foreland basin: Structural style and regional-scale deformation

“…15,16). The seismic section LS4a crossing the SCR preserved subsurface structures of the Chott Fejej and the northern side of the Telemzane arch or the Telemzane High (Gabtni et al, 2012;Gabtni et al, 2013;Dhaoui et al, 2014). The southwestern part of the seismic section shows a considerable thinning of the Mesozoic series above the faulted Paleozoic basement?…”

Syn-Collision Folding and Multi-Layers Detachment in the Molassic Basin, Northeastern Tunisia

“…(2) Oued El Meleh formation (Serravallian-Lower Tortonian): it consists of a 300 m thick evaporitic sequence made up of grey-greenish marls, passing upwards to lens-shaped to massive gypsum beds and some alternations of clays and sandstones [19,29].…”

“…8) shows a lateral variation of the Neogene deposits thickness in Kechabta basin. This variation is registered mainly by the thicknesses of Oued El Meleh and Kechabta for- [7,14,19,23,24] where it was explained by the existence of an erosion area during the Serravallian-Middle Tortonian. The main drawback of this hypothesis is that didn't take into account the original character of the sedimentary series, especially the incompetent nature of the Miocene formations.…”

“…This shortening phase is known as the post-Villafranchian phase [3,7,19,35,36,46]. This compression phase gave rise to NE-SW-and E-W-trending folds in Jbel Kechabta, Jbel Messeftine, and El Alia area.…”

“…At the Atlassic area of North African margin, the detachment is described in the Triassic evaporitic series [4,19,33]. The sedimentary cover detachment was revealed to be contemporary with the different stages of the African-Eurasian convergence that led to the Alpine chain and the Atlassic chain formation [3,15,40] during the Mesozoic-Cenozoic age.…”