Geologia Integrada Das Folhas Jequitaí, Bocaiúva E Montes Claros (1:100.000), Norte De Minas Gerais

Abstract

No mapeamento geológico (1.100.000) das folhas Jequitaí, Bocaiúva e Montes Claros, executado para a CPRM – Serviço Geológico do Brasil, foram reconhecidas sequências geológicas de idades mesoproterozóica, neopreoterozóica e fanerozóica. As rochas mais antigas (Mesoproterozóico) pertencem ao Supergrupo Espinhaço (indiviso), que aflora na porção sul da região enfocada abrangendo unidades siliciclásticas estruturadas em grandes anticlinais e metamorfizadas em fácies xisto verde. O Grupo Macaúbas (Neoproterozóico) ocorre nas bordas das faixas de exposição do Supergrupo Espinhaço, constituído por quartzitos e metadiamictitos, indivisos no mapa. O Grupo Bambuí (Neoproterozóico tardio) representa a sequência de maior expressão superficial, de natureza pelito-carbonática, onde se reconheceram as formações Serra de Santa Helena, Lagoa do Jacaré e Serra da Saudade, da base para o topo. Na unidade intermediária foram ainda individualizados os horizontes mais potentes de rochas calcárias. Sobrepõem discordantemente a essas três sequências, depósitos cretácicos (formações Abaeté e Urucuia) e fanerozóicos (coberturas inconsolidadas). Em termos estruturais, a região constitui dois domínios: a sudeste e a leste, ocorre a margem oeste da Faixa de Dobramentos Araçuaí, em contato com o Cráton São Francisco, onde rochas do Supergrupo Espinhaço e do Grupo Macaúbas encontram-se empurradas sobre a zona cratônica. Nesse outro domínio, sinclinais e anticlinais suaves expõem principalmente rochas do Grupo Bambuí. Os principais bens minerais explorados na região constituem diamantes, calcário e quartzo.

Quartz resources in the Serra de Santa Helena formation, Brazil: A geochemical and technological study

“…In the surroundings of both mines, several metamorphic minerals are reported. A detailed study of Chaves et al (2011) describes several occurrences of green schist in both the Serra de Santa Helena formation as well as in the Bambuí group, to which the studied formation is a part. This metamorphic terrain might be considered a partial evidence of a hydrothermal formation of the studied deposits.…”

“…Note that although the Olhos D' agua mine is outside the red area, it is linked to the formation(Chaves et al, 2011). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.…”

The 2012–2013 Montes Claros earthquake series in the São Francisco Craton, Brazil: new evidence for non-uniform intraplate stresses in mid-plate South America

“…This basement is comprised mainly of Arquean terranes of granitic/gneissic rocks. The Bambuí Group is represented by the Serra de Santa Helena, Lagoa do Jacaré and Serra da Saudade formations, which mainly consist of limestones, siltstones and argillites (Heineck et al 2004;Chaves et al 2011). The occurrence of carbonate rocks is highlighted in the area by the presence of several quarries near the urban area of Montes Claros (Fig.…”

Geological and hydrogeological review of a semi-arid region with conflicts to water availability (southeastern Brazil)

“…The urban zone of Montes Claros is located above these units, which could support the low groundwater productivity region. Even located in a pelitic domain, karstic features are also frequent, since the base of the Lagoa do Jacaré Formation presents carbonate intercalations (Chaves and Andrade, 2014b). The alternation between pelitic and carbonate sediments is also found in the region of Serra da Santa Helena Formation, as obtained in 35 well depth logs (ANA, 2018b).…”

“…The carbonate sequence is composed, on the base, mainly by metasiltstones from the Serra de Santa Helena Formation; limestones and metasiltstones in the intermediate portion belonging to the Lagoa do Jacaré Formation; and metamudstones and metasiltstones from the Serra da Saudade Formation at the top (Chaves and Andrade, 2014b). In structural features, there are large folds, corresponding to kilometric synclines and anticlines structures, with its limbs plunging to southeast and showing smoother dip than those that plunge to northwest.…”