GEOLOGY AND PETROGRAPHY OF THE Au ± Cu RAIMUNDA HILL, IN THE ALTA FLORESTA MINERAL PROVINCE (MT)

Abstract

The Raimunda mining is located in the Alta Floresta Gold Province, south of the Amazonian Craton, hosted in Granito Novo Mundo. The analyzes carried out showed the occurrence of two main host rocks of the mineralization: (1) tonalite; and (2) granodiorite. Six hydrothermal stages were recognized: (1) sodic alteration; (2) potassic; (3) seritic; (4) propylitic; (5) silica injection; e (6) late veinlets. The gold ore is confined, temporally and spatially associated with quartz ± carbonate veins, which correspond to the 5th alteration stage described. The ore is represented by the paragenesis pyrite ± chalcopyrite ± pyrrhotite ± sphalerite ± hematite ± bismuthinite ± gold. The characteristics of the Raimunda mining are similar with the disseminated gold systems confined to veins and quartz stockwork in calc-alkaline granites described in the province. The hypothesis adopted in this work is that the hydrothermal system and the sulphide and mineralized zones of the Raimunda mine formed from the development of an epithermal intermediate sulfidation system that superimposed (telescoped) a possible porphyry-type system.