Original paper

Mineralogy and Geochemistry of Weathering Zones on Itabirites, Quadrilátero Ferrífero, Minas Gerais, Brazil

Weggen, Joachim

Abstract

From the itabirites of the Proterozoic Cauê Formation (Itabira Group, Minas Series), high-grade iron ores developed in secondary processes. Late diagenetic to synmetamorphic influences resulted in hard, compact, metasomatic iron ores. They are distinguishable from enrichments due to weathering, where predominantly hydrated, porous high-grade ores are formed. These latter high-grade iron ores form the upper parts of the outcrops of the itabirites. They are closely related to erosional relicts of elevated old planation levels. Several peneplains are recognized, with altitudes from 1500 m to 900 m ranging in age from Jurassic to Pleistocene. In the area investigated (SE border of the Quadrilátero Ferrífero, Fabrica Mine), parts of the two oldest planation surfaces, and probably the next younger one, are still preserved. According to each of these successive planation levels, different high-grade ore bodys are exposed in the mining area.

Keywords

mineralogygeochemistryweathering zonesitabiritesBrazil