Gravity contributions to the understanding of salt tectonics from the Jebel Cheid area (dome zone, Northern Tunisia)

Abstract

A B S T R A C TDetailed gravity measurements integrated with geological data were computed to constrain the mechanisms that were active during the emplacement of the Triassic evaporite-bearing folds of Jebel Cheid from the salt-dome zone in the Atlassic region. The gravity analysis consists in mapping the contrasting gravity responses: complete Bouguer anomaly, residual anomaly and derivative maps; the main results display a positive amplitude gravity anomaly as the response of Triassic evaporite bodies and important NE-SW-trending features at the boundaries between the Triassic outcrops and their enveloping strata. In contrast with gravity calculations of a salt dome structure usually resulting in negative gravity anomaly models, the Jebel Cheid clearly expresses a positive gravity anomaly; furthermore, this result is supported by synthetic gravity interpretation.

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.…”

Structural Setting of Northern Tunisia Insights from Gravity Data Analysis Jendouba Case Study

“…The area of study belongs to the ''diapirc zone'' of Northern Tunisia, which is characterized by numerous Triassic outcrops generally elongated with a NE bearing; they bear gypsum, clay, some metasomatized basalts (sills, dikes), sands as well as lime-and dolostones. Due to its heterogeneous mixture, Triassic material would be denser (HAMDI NASR et al, 2007;HAMDI NASR et al, 2009), leading to the observed positive gravity response (HAMDI NASR et al, 2009;BENASSI et al, 2006).…”

“…In the region, an Early Mesozoic rifting phase has structured basin sunk salt dominated Triassic deposits, and was seconded by a passive margin tectonic basin style during the entire meso-cenozoic times. Moreover, Northern Tunisia has been the subject of several gravity data analysis (JALLOULI et al, 2002;JALLOULI et al, 2005;INOUBLI and MANSOURI, 2006;BENASSI et al, 2006;ROBINSON et al, 2007;HAMDI NASR et al, 2008;HAMDI NASR et al, 2009).…”

Gravimetric Study of Geological Structures of Teboursouk Area, Northern Tunisia

“…In our study, we used gravity data in the northern Tunisian Atlas collected by the Office National des Mines (ONM) [46] (gravimetric map of Teborsouk area). The studied area is covered by gravity stations on a 1 × 1 km 2 grid.…”

“…The Neogene formation is composed of Miocene marls. The Pliocene-Quatenary series shows a conglomeratic beds on the base and of sandy clay ones on the top [35,[41][42][43][44][45][46].…”