Contribution à l’étude géologique, géochimique et minéralogique des formations kaolinitiques du gisement de Tamazert El Milia (wilaya de Jijel).

Abstract

The present work intervenes in order to determine the mineralogical composition, the chemical composition of the geological formations of Tamazert. For this, two approaches were eeded, namely field and laboratory work. A sampling campaign was conducted through these trainings. The samples were collected from the Tamazert deposit, which is entirely based on the gneiss-dominated Kabyle bedrock. It is subdivided into 04 bodies in successive levels from bottom to top as follows: healthy gneiss, kaolinitized gneiss and sandy kaolin. The study area is affected by the weathering phenomenon that extends over almost the entire deposit. It is often characterized by different stages of evolution of chemical elements either by loss or gain. To better follow the evolution of this phenomenon, a sampling plan was carried out according to a depth profile. X-ray fluorescence (XRF) and mineralogical X-ray diffraction (XRD) analyzes were performed on some samples to better understand the phenomenon. The results obtained from the analyzes (XRD) revealed a kaolinitic dominant paragenesis associated with illite, chlorite as clay minerals and quartz, feldspar,plagioclase, associated with traces of magnetite, siderite as non-clay minerals. Overall, these proportions vary from site to site. The results of chemical analyzes of the major elements of Tamazert obtained showed a relatively high percentage of silica (SiO2) in high alumina (Al2O3), low in iron hydroxides (Fe2O3) in alkaline and alkaline earth (CaO, MgO) relatively low. These elements do not all react in the same way to leaching. This behavior has been confirmed by the DRX spectra. The interpretation of the results of the geochemical and mineralogical analyzes in addition to the petrographic description, indicate that Tamazert kaolin comes from the alteration of the feldspars under the effect of the hydrolysis.