Banca de QUALIFICAÇÃO: Caio Nonato de Oliveira Reis

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : Caio Nonato de Oliveira Reis
DATE: 08/12/2023
TIME: 14:00
LOCAL: Sala de videoconferência e Teams
TITLE:

AGUA AZUL DEPOSIT: METALLOGENESIS AND CONTROL OF MINERALIZATION, CARAJÁS MINERAL PROVINCE, PARÁ, BRAZIL.

KEY WORDS:

Granite-related; Gold; Metalogenesis; Carajas Province

PAGES: 66
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geologia
SUMMARY:

The Água Azul gold deposit is located in the southeastern portion of the Amazon Craton, in the Carajas Mineral Province, in the state of Para, Brazil. It currently contains a resource of 1.4 Moz at 2.50 g/t Au and remains open at depth and along strike mineralization. The main host rocks of the deposit are sericite-biotite gneisses and hornblende-biotite mylonite with disseminated and/or massive sulfides in quartz veins, shear zones and breccia zones with magnetite/hematite, in addition to containing significant content of hydrothermal scheelite in some portions of the deposit. This work is the pioneer of the Agua Azul deposit and to carry out the comprehensive characterization of structural controls, hydrothermal alteration facies, paragenetic sequence of minerals, styles of mineralization and relative timing of mineralization of gold and associated sulfides in the deposit, the project was based on in the examination of drill cores, whole rock chemical data, petrographic analysis and mineral chemistry in chlorites and silicates. The ore body has a hydrothermal gradation that begins with sodic alteration (albite-scapolite), which grades to calcic-ferric (amphibolemagnetite-pyrite), intense and pervasive K-Fe-Ba alteration (k-feldspar and muscovite with barium -biotite-magnetite) which is superimposed by Na-Fe/Post-mineralization (albite-hematite-epidote-carbonate), the sulfide breccias and veins with higher gold contents are recorded together with the potassium hydrothermal halos. The results obtained from the chlorite temperature indicate values of 262.76°C (±15.75°C) and 227.74°C (±43.05°C). Gold occurs mainly as “invisible gold” included in pyrites and in free form as visible gold with sizes varying from 10µm to small millimetric aggregates, and it is common to associate the presence of gold with tellurobismutite. Analysis of whole rock chemical data shows an association of mineralization with granitophiles elements such as W-Bi-Te-Y and the Au±Cu association. This result is correlatable to the granite-related, Cu-Au (W-Bi-Sn) Paleoproterozoic deposits of Carajás, as well as Ni-Co-Cr enrichment that may have been leached from local ultramafic rocks. Dating, isotopic analyzes and mineral chemistry on sulfides will be carried out later to better define the proposed genetic model for the Agua Azul deposit.

COMMITTEE MEMBERS:
Interno - 418965 - CLAUDINEI GOUVEIA DE OLIVEIRA
Presidente - 2697315 - MARIA EMILIA SCHUTESKY
Interno - 6404885 - NILSON FRANCISQUINI BOTELHO
Interna - 2341034 - ROBERTA MARY VIDOTTI
Interno - 1057547 - VALMIR DA SILVA SOUZA