Deep structure of the Chott Jerid trough (Southern Tunisia)
The surface monotony and ambiguous structure of the Chott Jerid (low topographic area covered by a Quaternary series) induce the possibility of the existence of an important subsiding trough (E-W collapsed bock) and associated faulted zones. This geophysical study allowed a defining of the characters of the deep structures and architecture of this depression. The general trend is E-W in the 3D Bouguer gravity structure and it is confirmed by 3D time structure of major deep seismic horizons. The existence of a culminated Hercynian High (Telemzan High) on the southern border of the Chott Jerid Trough induced a generally subsiding in the north probably began with "En escaliers" normal faults in the Upper Carboniferous. The existence of a series of deep E-W zone faults along the southern border of the trough is recognized in seismic profiles, magnetic intensity curves and gravity anomalies maps (Edge enhancement analyses) and corresponds to the great North Saharan Flexure or "NSF". In reality, the "NSF" is the responsible for the structural establishment of the totality of the Atlasic sedimentary basin including the Chott Jerid Trough.