The structure of Jebel El Mourra, Tunisia: a diapiric structure causing a positive gravity anomaly

Abstract

Detailed gravity data integrated with geological data and mining well data are analysed to constrain the shape of the Triassic evaporitic body at Jebel El Mourra (northern Tunisian Atlas) and the mechanism of its emplacement at the surface. The gravity data analysis included the construction of a gravity anomaly maps, and synthetic and forward 2.5D gravity models. The complete Bouguer and residual gravity anomaly maps indicate a positive amplitude gravity anomaly over the Triassic evaporitic outcrops and prominent NE–SW‐trending features associated with the boundary of the Triassic rocks and surrounded layers. A NW–SE‐trending gravity model that crosses the Triassic evaporitic outcrop at Jebel El Mourra shows that the positive gravity anomaly can be explained by a deep‐rooted salt diapir. Conventional models of salt dome formation suggest that they produce negative gravity anomalies; however, this study shows that this model is not universal. The studied area is an example of a diapir expressed by positive gravity anomaly and this result is supported by synthetic gravity models at different stages of salt piercing.

Morphotectonic and Morphodynamic investigations revealed by isobase surfaces analysis and derived differential mapping using GIS, Teboursouk area, northern Tunisia

“…However, the original mechanism of salt halokinesis and model of salt rising are considered, until today, as the most controversial subjects of debate regarding the morphostructural evolution of the northern Tunisian Atlas. In fact, most of Triassic extrusions have been explained by a diapiric mechanism which is considered as the generator of salt rising inside the folded Triassic structure (Perthuisot 1978;Hammami 1999;Perthuisot et al 1999;Jallouli et al 2002;Benassi et al 2006;Benassi 2011), whereas Vila et al (1994Vila et al ( , 2002 and Ben Chalbi et al (2006) have interpreted the same structures as being formed by large-scale allochtonous salt (glacier salt) movements interbedded within the Cretaceous series.…”

Apport de la gravimétrie à l’étude des structures effondrées du Nord-Est de la Tunisie: implications hydrogéologiques

“…Le succès de l'application de cette méthode dans la marge atlasique de la Tunisie a été prouvé au niveau des études antérieures (Jallouli et Mickus 2000, Jallouli et al 2002, Benassi et al 2006, Haj Sassi et al 2006, Azaiz et al 2011, Gabtni et al 2011.…”

Structuration profonde dans la région de Bir M’Chergua (Nord-Est de la Tunisie). Implications hydrogéologiques

“…7) Jebel Cheid, Jebel Mourra et Lansarine (Benassi et al, 2006;Hamdi Nasr et al, 2009;Amiri et al, 2011;Sarsar Naouali et al, 2017). Ces réponses indiquent la présence des roches denses comme l'anhydrite et la dolomie en subsurface.…”