Paléoenvironnements de dépôt et transformations post-sedimentaires des sables fauves du bassin du sais (Maroc)

Abstract : The "Fawn sands" are constituted of detrital elements of quite complex history, reshaped from older and contemporaneous sedimentaries laterally settled. The different results obtained from the sedimentologic study executed on these sands confirm the marine nature of this formation. The age of sequence is specified by the Globorotalia crassaformis that gives middle Pliocene age. It's a series that registers the marine transgression of the middle Pliocene ("Moghrebien") caused by the relative rise in sea level in this era. The sea enters then into the region of Fez. The Sais basin constituted thus an open gulf to the west on the Atlantic ocean. The basin geodynamic evolution is related to the rise of the south-rif Ridges and the isostasie uplift of the meseto-atlasic domain. By another way, the Sais basin had been subsiding. The erosion of the young reliefs under a humid paleoc1imate leads to an increase of the detritic supplies. The filling up of the basin by sedimentary supplies associated with the lowering of relative sea level during the late middle Pliocene and the rise again of the El Kansara limit are the cause of the final sea recession of this basin. After the emersion, the warm and humid paleoclimate favored the development of a ferralitic paleoalteration. The redistribution of the iron oxides by the phreatic and meteoric waters caused the marine sands marmorosis which allowed these sands to be called "Fawn sands". The paleoc1imate change, which becomes drier, induced continental deposit in which we have discovered larval Hymenopetra cells belonging to the ichnogenus Cellifonna.
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Khadija Boumir. Paléoenvironnements de dépôt et transformations post-sedimentaires des sables fauves du bassin du sais (Maroc). Sciences de la Terre. Université Henri Poincaré - Nancy 1, 1990. Français. ⟨NNT : 1990NAN10377⟩. ⟨tel-01777328⟩

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