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Cover of Hoggar
the cover begin with the molasses from the purple series (Eocambrien-Cambrien) and/or the sandstones from Tassili (Ordovicien) which overcome in discordance the former formations deeply deteriorated by a pedogenese lateritic.

  • Cambrien
    the transgression eocambrienne, which occurs in continental context (glaciation, wind dunes), comprises the traditional terms, conglomerates tillitic, dolomites, mudstones and silexites. It is acted in fact, pro leaves, of deposits cineritic and ignimbritic marking a significant volcanicity rhyolitic at that time (dated between 538 and 520 My, Allgre and Caby, 1972; Clauer and Al, 1982) and whose traces are known until the South of Mauritanides. In this area, at the Western end of the basin of Taoudeni, this volcanicity would be slightly older (dated has 610 My, Lahondere and Al, 2005)
    the formations cambriennes are dominated by the sandy and conglomeratic facies. Their thickness reaches 300 m more in North in the basin of Hassi Messaoud (oil surveys).

  • The Ordovicien
    Ordovicien forms riverwashes around the emerged small islands. The marine facies are more at North, in the chain of Ougarta. The glaciations mark in the final facies.

  • The Silurien
    Like everywhere in the world, the silurien is characterized by the marine black mudstone deposit, with graptolites.  They are powerful here approximately 600 m and comprise rare carbonated intercalations.

  • The Dévonien
    lower Dvonien is primarily argilo-sandy.  The strongest thicknesses (850m and 400m) are recorded in the basins of the wadi Mya (the Northern Sahara), Tindouf and Ougarta.  Average and higher.

Dvonien often lacunar or is eroded (erosion frasnienne, famennienne and pre-msozoque).

  • The Carboniferous
    Little carboniferous appears on the southern edge of Hoggar.

  • Mesozoque (Cretaceous)
    the Cretaceous, present everywhere on the Saharan platform, evolves in detrital coarse (conglomerates) at end (argilo-sandy) at the base, with carbonated at the top. Locally are intercalated more confined facies (gypsum).

  • The Cenozoic
    The Quaternary one corresponds to gravels, file, deposits of playas, sand regoliths and dunes. A significant alkaline volcanicity develops of the Eocene higher than sub-current (see below).

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