Mineral potential re-evaluation of the Seis Lagos Carbonatite Complex, Amazon, Brazil

Abstract

The Seis Lagos Carbonatite Complex hosts a lateritic deposit developed over a siderite carbonatite. In the 1980’s, it was estimated to contain 2.89 Bt @ 2.81 wt% Nb₂O₅. Recent studies have produced new data allowing re-evaluation of the area’s mineral potential. In this work, a geological model has been constructed and new estimates of grades and tonnages are presented. The volume of cavities that occur in the lateritic crust is still unknown, and it was then segmented in possible scenarios ranging from 0 to 63%, impacting estimates of tonnage. The estimations were divided into two domains that vary according to the available data. In Domain 1, it has been estimated between 10.5-28.3 Mt @ 2.97 wt% Nb₂O₅ and 0.71 wt% REE₂O₃, and in Domain 2, between 1.40-3.78 Bt @ 1.17 wt% Nb₂O₅ and 0.46 wt% REE₂O₃. High grades of Ti, Sn and W were also detected for the lateritic crust. It is estimated that sediments in the Esperança Basin contain 11.8 Mt @ 1.76 wt% REE₂O₃ and 2.36 wt% P₂O_5, whereas the siderite carbonatite shows high grades of Nb, REE, Sc and Zn, further increasing the area’s mineral potential. Soil grids on neighboring hills do not show similarly high Nb grades, but do present high grades of REE and P.

KEYWORDS:
laterite; carbonatite; niobium; rare earth elements; Amazon; Brazil