Anomalias de Au em sedimentos fluviais associados à Suíte Cacoal no projeto geologia e potencial mineral do centro-leste de Rondônia: resultados preliminares

• Autor(a) principal: OLIVEIRA NETO, Wilson Lopes de
• Data de Publicação: 2024
• Outros Autores: SANTOS, Caroline Couto, SILVA, Dalton Rosemberg Valentim da, PROVENZANO, Carlos Augusto Silva, BERGAMI, Gustavo Negrello, PINHEIRO, Marco Aurelio Piacentini, OLIVEIRA, Carlos Eduardo Santos de
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Repositório Institucional de Geociências - RIGEO
• dARK ID: ark:/79692/00130000092br
• Texto Completo: https://rigeo.sgb.gov.br/handle/doc/25355
• topic: RECURSOS MINERAIS; GEOLOGIA ECONÔMICA; EXPLORAÇÃO GEOQUÍMICA; SEDIMENTO DE CORRENTE; OURO; RONDÔNIA; MINERAL RESOURCES; ECONOMIC GEOLOGY; GEOCHEMICAL EXPLORATION; STREAM SEDIMENT; GOLD; FIRE ASSAY

This technical report presents the preliminary results of the geochemical survey of river sediments, an action of the Geology and Mineral Potential of the Center-East of Rondonia Project, carried out by the Geological Survey of Brazil. The project consists of the geological mapping of four sheets at a scale of 1:100,000, in the region of the municipalities of Cacoal, Espigão d’Oeste and Pimenta Bueno, in the state of Rondônia. The sampling density was approximately one sample every 15 km², the chemical analysis occurred through digestion with aqua regia and reading by ICPMS/OES for 52 elements and through 50g of decomposed, fused, cupellated sample, digested with acid and read by the ICP-MS for Au, Pd and Pt. Another sample, with heavy minerals concentrated in situ, was subjected to mineralometric analysis with native minerals count. The results revealed ten main zones of gold mineral occurrence and six anomalous zones, with gold grades between 15 and 1420 ppb. The Zone 1 indicated regions of mineral and anomalous occurrence that are located in geological environments such as the sequence of the Neoproterozoic Parecis Sedimentary Basin, but mainly related to the paleo to mesoproterozoic basement with the São Romão Granitic body, Roosevelt Group, Serra da Providência Suite and the stratified mafic-ultramafic Suite of Cacoal. Anomalous Zone 1 stands out for presenting the highest gold levels found, as well as the largest number of gold mineral occurrences in this survey combined with its potential for Ni-Cu-PGE and gold mineralization, reported in previous exploration works.