Mineralogy, geochemistry and parent rock of Décio bauxite-bearing lateritic profile (Rondon do Pará, Eastern Amazon)

Cenozoic world-class bauxite deposits developed on sedimentary sequences of the Parnaíba and Amazon Basins. The Décio pilot mine, excavated in Rondon do Pará deposit, exposes a 3 m thick bauxite-bearing lateritic profile top 350 high plateau. From base to top, this is composed clayey bauxite; porous microcrystalline spherulitic ferro-aluminous duricrust, fragmentary top; as well loose spherulites nodules, embedded clay. lower horizons represent classic succession, while was produced through post-lateritic reworking. During process, Ga, Cr, Mo, As, Pb, Hg, Sb, Zn, V Sc were captured by iron oxi-hydroxides; REE, Hf, Nb, Ta, Y remained carried relict zircon. Isocon diagram mass balance demonstrate affinity with claystone from Itapecuru Formation.