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Géologie du Précambrien terminal (III) et traitement statistique des données géochimiques de prospection, dans la boutonnière de Bou Azzer - El Graara (Anti-Atlas, Maroc)

Abstract : This study was performed in the Bou Azzer-El Graara panafrican suture zone (Anti-Atlas, Morocco). This work is divided in two parts: on one hand, the geological and geodynamical study of the late Precambrian (PIII) as support for the statistic processing of prospecting geochemical data from the Tamdrost-Ambed district on the other hand. 1) The definition of the lithological groups is based on detailed geological map of Tamdrost-Ambed district on 1/4000e scale and columnar sections from whole the inlier lead to a synthetic columnar section and lithostratigraphic correlations. The Precambrian III predominantly pyroclastic rocks' petrography, reveales a calc-alkaline afinity for the 580 to 560 Ma old magmatism event, whose geodynamic significance is discussed. The structural analysis of the Precambrian III formations has revealed synvolcanic deformations in a NW -SE extensional regime and has led to detennine the principal stress directions. The extensional model proposed suggests a left-lateral strike-slip parallel to the panafrican suture, between the W -african craton and a "mobile" panafrican area. II) The statistical data processing of 13000 spectrometry analysis of 10 major elements and 24 trace elements,leads to establish significant elementary and multi-elementary geochemical anomalies which are independant of the lithology. Study of the geochemical data quality leads to the analytical precision evaluation and consequently allows empirical correction of the analytical error. The statistic analysis of prospecting geochemical data was realised in several steps: - the non conventional method "box and whiskers" for the threshold detennination on all lithologies. - the lithological complexity is simplified by factor analysis on medianes to define 4 lithological groups instead of the 32 recognized during field work. - a discriminant analysis on those 4 defined groups, leads to geochemical background factorial modeling, which gives better explanation of geochemical variations related to lithology. - factorial regression based on this model reveals unconformable anomalous component of the geochemical variation. Synthetic multi-elementary anomalie maps are produced to direct prospecting legs.
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Submitted on : Tuesday, September 3, 2013 - 9:11:26 AM
Last modification on : Friday, March 25, 2022 - 11:10:20 AM
Long-term archiving on: : Thursday, April 6, 2017 - 2:29:57 PM


  • HAL Id : tel-00708240, version 2



Moulay Azizi Samir. Géologie du Précambrien terminal (III) et traitement statistique des données géochimiques de prospection, dans la boutonnière de Bou Azzer - El Graara (Anti-Atlas, Maroc). Géochimie. Université Joseph-Fourier - Grenoble I, 1990. Français. ⟨NNT : ⟩. ⟨tel-00708240v2⟩



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