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The chain of Ougarta set up on the site of an old furrow subsident which borders in the east the margin of African Western Craton (Menchikoff, 1949; Fabre, 1969). It was affected during the orogense hercynienne by crumplings of major direction NW-SE and E-W, generated by the great fractures of the base whose play is primarily vertical (Donzeau, 1972). It is subdivided, according to a direction NW- SE, in two beams separated by Erg-er-Raoui: the beam of Saoura with and the beam of Daoura with the SW.

From a lithostratigraphic point of view, the area is made up:

- of a volcanogenic and volcanic base which appears in buttonholes in the heart of the anticlines, whose age is supposed Precambrian terminal by comparison with its equivalent of the Moroccan Anti-Atlas and without valid absolute dating

- of a thick folded series of Palozoque age, with dominant terrigenous and carbonated, which surmounts in discordance the Precambrian one. This series, affected by the orogense hercynienne, present of structural directions N120E known as ougartiennes.

The polygenic conglomerate of Ben Tadjine, traditionally considered as the basic conglomerate of Paleozoic, would be in fact a molasse basal tardi-panafricaine deposited during Néoprotérozoïque and folded during late Panafricain (Bouima and Mekkaoui, 2003). It could also contain levels tillitic neoproterozïc, as those of the edge of the basin of Taoudeni.

Ougarta is a chain overlapping with weak shortening, ordinate of towards the SW, in which five units were individualized: two for the beam of Saoura; two for the beam of Daoura; a last finally representing the indigenous one or the tectonic foreland of the chain (Hervouet and Duee, 1996).

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