Caracterização dos perfis da cobertura Lateríca dos furos N4WS1398 & N4WS, Serra dos Carajás, Pará

Abstract

Petrographic analysis of the profiles of the lateritic cover on the Sierra Norte de Carajás, plateau N4WS is changing product BIF and basalts, occurring in N4WS-1398 boreholes and N4WS-1495. The lateritic deposits correspond to the gaps conglomerated intrabacinais type of BIF fragments and extra-bacinais sediments related to source areas of sedimentary and metamorphic rocks. Were used of geological parameters, mineralogical and petrographic (XRD methods, SEM and optical microscopy) to further characterize the lateritic profile of these surveys holes. The FFB fragments, minerals monocrystalline and polocristalinos quartz constiturm the main components forming rocks, in association with iron oxi-hydroxides (goethite and hematite), aluminum (gibbsite and bohemita) and clay minerals (caulilita, esmectita etc) as the main trainers representatives of the cementing process. In Carajás (PA) covers lateritic are covering and associated with iron ore deposits. The lateritization deposits of banded iron formation, characterized by soil reddish color, coming from iron hydroxide accumulation process of detrital sediments, allowed the generation of thick lateritic resulting debris flow generated by BIF rocks of wearthernig and basalts of Carajás and Igarapé Cigara formations.