Elementos-traço em pirita e calcopirita por microssonda eletrônica em depósitos auríferos filonares da Província Aurífera de Alta Floresta (MT), Cráton Amazônico

• Autor(a) principal: Meyer, Andrey [UNESP]
• Data de Publicação: 2017
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/203234; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2018-12-11/000909788.pdf
• topic: Mineralogia; Calcopirita; Ouro - Minas e mineração; Crátons; Depositos hidrotermais; Sulfetos minerais; Alta Floresta (MT)

The Alta Floresta Gold Province (AFGP) is located at southern Amazon Craton (northern of Mato Grosso State), it consists of plutono-volcanic paleoproterozoic sequences, that host more than a hundred medium- to high-grade and small size deposits aligned along the Peru-Trairão belt (NW-SE). The province's gold mineralization are individualized into four main groups: (1) Au ± Cu disseminated; (2) vein-type Au ± Cu; (3) vein-type and/or disseminated Au ± Cu + Mo; and (4) vein-type Au + Zn + Pb ± Cu. These deposits represent magmatic-hidrotermal systems, which are usually interpreted as Au ± Cu porphyry systems or as epithermal gold-systems of low to intermediate sulfidation. In this context, the objective of this study is the determination of trace elements in pyrite and chalcopyrite from Paraíba and Edu deposits, which represent vein-type Au ± Cu deposits of group (2). The petrography analysis of mineralized zones allowed the recognition of five textural variations of pyrite (pyrite I, pyrite II, pyrite III, pyrite IV and pyrite V) in the Paraíba deposit, as well as two varieties in the Edu deposit (pyrite of milonitic ore and granitic ore). At the SEM, the pyrite from both deposits was homogeneous, without mineral zoning. The electron microprobe data set revealed that several elements show concentrations above the detection limit, as Pb, S, Au, Ti, Ag, Zn, Cu, Ni, Co e Fe. However, the elements Al, As, Sb and Cr were shown below the detection limit in almost all analysis. The gold concentrations have been between 90 and 1740 (ppm) in Paraíba deposit and between 90 and 1150 (ppm) in Edu deposit. In addition, the analysis obtained high concentrations of Ni (<65 - 1040 ppm) and Co (590 - 1920 ppm). The Au presented moderate and positive linear correlations with Pb, but negative with Ni, Cu and Co in pyrite, also positive correlations with Co and Fe, but negative with Pb and Zn in chalcopyrite. These variations can be explained from...