The geology, geochemistry, properties and origin of the Minim-Martap bauxite deposit (Adamawa region, Cameroon)

In this study, the jeochemical composition, geology, and quality and origin of the bauxites on the three plateaus deposit and Terra-Rosa from the Minim-Martap Bauxite Province in the Adamawa Region of Cameroon were evaluated. Bauxite can be defined as a soil or rock formation that is composed mainly of alumina (aluminium hydroxide, that is Gibbsite, Boehmite and to a lesser extent diaspore mineral) minerals together with iron oxide minerals (haematite and goethite), clay minerals (mainly kaolinite), quartz, and small amounts of anatase (TiO2) and water, including a variety of other minerals. It is the main Ore from which 99% of all the aluminium has been produced. From this Minim-Martap Bauxite province, 41 bauxite samples were collected from the Danielle Plateau (15 samples), Yolan Plateau (09 samples) and Minim-Martap Plateau (17 samples) Plateaus, while 11 Terra-Rosa samples were collected from all three plateaus and their environs. The bauxite samples were prepared and analyzed separately in groups according to their location while the Terra-Rosa samples were jointly analyzed. The samples were analyzed for their Major, Trace and Rare Earth element, while the weathering indices of the samples were also calculated using the Ruxton Ratio and the Chemical Index of Alteration. Geochemical analysis for the plateau reveals average concentration Al2O3 in order of Minim-Martap (54.87%) > Danielle (43.73%) > Terra-Rosa (30.57%) > Yolan (26.90%) - Indicating the Minim Martap plateau has the best quality bauxite; for Fe2O3 as Yolan (47.41%) > Danielle (24.53%) > Terra Rosa (16.75%) > Minim-Martap (7.17%) – indicating Yolan could be an iron rich deposit; for SiO2 as Terra-Rosa (27.75%) > Yolan (3.80%) > Minim-Martap (2.44%) > Danielle (2.12%) – Indicating the Terra-Rosa are more clayey; for TiO2 as Minim-Martap (4.54%) > Danielle (3.54%) > Terra Rosa (2.98%) > Yolan (2.49%); and the average concentration of the ΣREE is of the order Minim-Martap (829.4%) > Terra Rosa (266.6%) > Danielle (245.8%) > Yolan (115.2%). In addition to the low values of the alkali and the alkali earth metal, the weathering indices of sample groups indicates averagely very low Ruxton Ratio R < 1 and averagely very high values of CIA > 98, all of which support intense weathering origin of the bauxite deposits and Terra- Rosa. All the plateau samples show very strong lateritization but for the Terra-Rosa samples show mostly moderate lateritization. The possible source of the magma that formed the precursor rock of the laterite may not have come from the mantle. The Minim-Martap plateau deposit is a low iron rich bauxite deposit, the Danielle plateau a ferrugineous bauxite deposit, the Yolan plateau a bauxitic iron ore deposit and The Terra-Rosa is composed mainly of kaolinitic bauxite. The precursor rock of the Danielle plateau and the Minim-Martap deposits are mafic basaltic-andesite igneous rocks with intermediate pH (basic–acidic characteristic); the Yolan is an ultramafic to mafic basaltic-andesite igneous rocks with intermediate pH and the Terra-Rosa formed from the basic basaltic-andesite igneous rocks.