Título:	Assinatura Geofísica da Ocorrência de Sulfeto Maciço da Formação Digo-Digo e Implicações para a Seleção de Alvos Potenciais no Greenstone Belt Serra de Santa Rita, GO
Autor(es):	Amaral, Pedro Augusto Costa do
Orientador(es):	Toledo, Catarina Labouré Bemfica
Coorientador(es):	Borges, Welitom Rodrigues
Assunto:	Formação Digo-Digo Sulfetos maciços Prospecção mineral Prospecção Geoelétrica
Data de publicação:	17-Nov-2021
Data de defesa:	28-Mai-2021
Referência:	AMARAL, Pedro Augusto Costa do. Assinatura Geofísica da Ocorrência de Sulfeto Maciço da Formação Digo-Digo e Implicações para a Seleção de Alvos Potenciais no Greenstone Belt Serra de Santa Rita, GO. 2021. 117 f., il. Dissertação (Mestrado em Geologia) — Universidade de Brasília, Brasília, 2021.
Abstract:	The Archean-Paleoproterozoic Crixás-Goiás Domain (CGD) is situated in the Tocantins Province, central-west region of Brazil. About 80% of the Crixás-Goiás Domain corresponds to archean granite-gneissic terrains, and the rest of the block consists of supracrustal sequences distributed in five Archean-Paleoproterozoic greenstone belts. The principal epigenetic gold deposits in the central-west portion of Brazil are within these greenstone belts, such as the mines of Crixás (7 Moz), Pilar (0.7 Moz), Guarinos (6.5Moz), and Faina (approx. 500Koz). In addition to the epigenetic deposits, syngenetic occurrences of gold, iron, manganese, and base metals in these terrains are known but are still under-researched. In the southern portion of the CGD is situated the Serra de Santa Rita greenstone belt, where gold occurrences associated with massive sulfides have been known since the 1970s when the company Metais de Goiás (METAGO) carried out the first exploration program in the region. In the Serra de Santa Rita greenstone belt, the basal portion consists of volcanic rocks of ultramafic composition that characterize the Manuel Leocádio Formation, followed by mafic volcanic rocks of the Digo-Digo formation, which contains intermediate to felsic volcanic rock lenses. At the top occurs metric exhalative horizons composed of metacherts with intercalations of carbonaceous phyllites, rich in pyrite and gold. The Digo-Digo Formation has located 5 km from the City of Goiás, its metavolcaniclastics lenses of intermediate compositions with extensions above 3km have great potential for host a diversity of VMS-type deposits. Today, new mineral discoveries require sophisticated analysis and interpretation. Recently, 2-D and 3-D inversions of geophysical data were applied to the identification and imaging of ore bodies with contrasting physical properties, such as massive volcanogenic sulfide (VMS) deposits, that ore properties are very different from the properties of their host rocks. The present research applied induced polarization (IP), resistivity, ground magnetometry, and magnetic susceptibility measurements to identify geophysical signatures and detect targets associated with massive sulfide occurrences in the Digo-Digo Formation. The results obtained were divided into two articles. The first article presents time and frequency domain electrical data acquired over the exhalative horizon of the Digo-Digo Formation, positioned at the confluence of the Digo-Digo Creek with the Vermelho River. The IP data integration (time and frequency domain) in a ternary RGB model permitted the identification of extensive zones with potential for sulfide mineralization. Then a geological-geophysical section was designed based on the RGB model, where were identified four restricted targets in geologically favorable zones. The second article presents 2D and 3D inversions of magnetic and IP data to detect the geophysical signature of massive sulfides occurrences and generate new potential targets. In the magnetic maps, magnetic structures and lineaments presented a locally good correlation with inferred mineralized zones on the surface. Magnetic susceptibility measurements and models demonstrated that zones with values above 0.003 SI might be prospective for massive sulfides. The magnetic susceptibility measures show that ambiguities in magnetic data interpretation can occur due to magnetite-chlorite schists with similar susceptibility values to obtained for massive sulfides. The susceptibility models permitted the identification of four magnetic bodies (targets) with values greater than 0.0049 SI that might be associated with surface mineralizations in the area. The massive sulfide zone tested by drilling (drill hole GDD001), is located marginally a strong magnetic (>0.003SI) and chargeability (>40mVN) anomalies in 2D sections and corresponded in the susceptibility model to a 900m length magnetic body (plan view). The highest magnetic susceptibility anomaly presented a circular geometry interpreted as a non-outcropping intrusion, maybe with a role in the metallogenetic processes. The geophysical methods applied in this research demonstrated efficiency in the direct detection of known mineralizations and new prospective targets associated with massive sulfide occurrences. The efficiency of these methods in detecting and identifying the geophysical signature of these Au-Cu occurrences can have direct implications for target generation in the basal units of the greenstone belts of Crixás-Goiás Domain.
Unidade Acadêmica:	Instituto de Geociências (IG)
Informações adicionais:	Dissertação (mestrado) — Universidade de Brasília, Instituto de Geociências, Programa de Pós-Graduação em Geologia, 2021.
Programa de pós-graduação:	Programa de Pós-Graduação em Geologia
Licença:	A concessão da licença deste item refere-se ao termo de autorização impresso assinado pelo autor com as seguintes condições: Na qualidade de titular dos direitos de autor da publicação, autorizo a Universidade de Brasília e o IBICT a disponibilizar por meio dos sites www.bce.unb.br, www.ibict.br, http://hercules.vtls.com/cgi-bin/ndltd/chameleon?lng=pt&skin=ndltd sem ressarcimento dos direitos autorais, de acordo com a Lei nº 9610/98, o texto integral da obra disponibilizada, conforme permissões assinaladas, para fins de leitura, impressão e/ou download, a título de divulgação da produção científica brasileira, a partir desta data.
Agência financiadora:	Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).
Aparece nas coleções:	Teses, dissertações e produtos pós-doutorado

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