Abstract
In this paper an evaluation is made over the geochemistry signature of
major elements in lateritic rocks on the counties of Granja, Martinopole
and Parazinho, Northwest of Ceara State. Geologically, the area is
located in Medio Coreau Domain, characterized by the Granja Complex,
which is the geological basement of the region, composed by gneiss,
granulites and migmatites, and supracrustal sequences formed by
quartizites and phyllites of Martinopole and Ubajara Group, and also
cenozoic sediments of Barreiras Formation. Laterites are normally found
in humid weather (seasonal or not), so it is more likely that the
generation process of this lateritic beds were under ancient climatic
conditions, totally different from the present. The laterites are
associated with gneiss, quartzites and phyllites. The prevailing
laterization process is the metal enrichment, especially iron. Iron
content varies from 34.69 to 77.85% in the altered rock samples; this
trend being more evident in gneiss, in which iron enrichment exceeds
75%. Al content increases 6 to 7% in altered rocks. Sm-Nd data showed
that the ratios obtained in these laterites are similar to the
protoliths and can be used to define autochthonous from allocththounus
laterites and also confirm Sm and Nd mobility in the laterization
process.
Links and resources
Tags