Contexto geológico e estrutural do Maciço Rio Apa, sul do Cráton amazônico - MS

Rio Apa Massif crops out in the Mato Grosso do Sul state and corresponds to the southeastern portion of the Amazonian Craton dominantly Paleoproterozoic in age. Rio Apa Complex is oldest and it is composed mainly by migmatitic orthogneisses, beyond amphybolites, tonalities and granodiorite. Alto Tererê Group is composed by schists, biotitemuscovite gneisses and micaceous quartzites generally rich in garnets, beyond metabasic rocks of low amphibolite facies. The Amoguijá Group is constituted by Alumiador Intrusive Suite, which is represented by a sieno to monzogranitic batholith and Serra da Bocaina Volcanic Suite composed of volcanoclastic rocks of alkali riolites to monzoriolites compositions and pyroclastic products. Overlaying towards East and South occurs Neoproterozoic metasedimentary rocks from the Paraguai Folded Belt (Cuiabá, Corumbá and Jacadigo Groups - Urucum Formation). Structural-metamorphic framewok is identified by five deformational phases but the actual tectonic and metamorphic structure shows the superposed tectonic array of the Paraguai Folded Belt. Rocks from Rio Apa Complex, Alto Tererê Group and Amoguijá Group record an older structural evolution defined by (Dn-1 and Dn). The deformational phases (Dn+1 and Dn+2) are visible mainly in rocks of Paraguai Folded Belt beyond the last deformation (Dn+3) that imprints all sequences.

Rochas ornamentais e de revestimento do sudoeste do estado do mato grosso

Geological, petrographical, chemicals and technological studies of rocks of the southwest region of Mato Grosso State, Brazil have the purpose of qualification and application of these rocks as dimension stones. The first objective is to enlarge the offering of new esthetic varieties that show a standardization of technologic patterns, adequate characterization and classification assuring the correct specification of the rocks in relation to the use as dimension stones. Ten rock types are recognized for dimension stones, including granites, diabases, gneisses and amphibolites grouped by its colors in red, grey and black types and showing economic potential of plowing. The results obtained in the technological essays show that the rock parameters are sited inside the standard limits established by technical rules and obey satisfactorily the limit values fixed for granites in internal and external covering uses.

Suíte vulcânica serra da bocaina, grupo amoguijá, maciço rio apa-MS

The Rio Apa Massif corresponds to the southeastern portion of the Amazonian Craton and crops out in the Mato Grosso do Sul State, Brazil. It is constituted by rocks of paleoproterozoic age of Rio Apa Complex, Alto Tererê Group and the plutonic-volcanic suites of the Amoguijá Group, subdivided in Alumiador Intrusive suits and Serra da Bocaina Volcanic. The Volcanic Suite is represented by São Francisco and Bocaina mountains and is constituted by terms of the composition of alkali - rhyolitic to rhyolitic, including in minor amounts riodacite, andesite and dacite. It consists of a variety of textual subvolcanic rocks, volcanic and varied volcanoclastics. The pyroclastic deposits are very expressive and consist of pyroclastic particle immerse in aphanitic matrix, fine grained or amorphous, where quartz, feldspar, chlorite, sericite, microlithes of carbonate, sparse spherulites and reliquiar volcanic glass can be distinguished. The pyroclastic rocks are represented by breccias, ignimbrites, agglomerate, tuffs, lapillistones and pumices and contain commonly vitroclasts, lithoclasts and crystalloclasts, pumices, fiammes, glass shards, spherulites, vesicles and amygdales. They are calc-alkaline rocks with dominant peraluminous character high to middle potassium series and define a sin-colisional dominant tectonic and are genetically associated to the evolution of the Amoguijá Magmatic Arc.

Caracterização geológica e tecnológica de unidades gnáissicas e graníticas do sudoeste de Mato Grosso para fins de exploração como rochas ornamentais e para revestimento

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

SUÍTE VULCÂNICA SERRA DA BOCAINA, GRUPO AMOGUIJÁ, MACIÇO RIO APA - MS

O Maciço do Rio Apa corresponde à porção meridional do Cráton Amazônico no sudoeste do estado de Mato Grosso do Sul e é constituído pelas rochas de idade paleoproterozóicas do Complexo Rio Apa, Grupo Alto Tererê e suítes plutono - vulcânica ácida do Grupo Amoguijá, dividido em suítes Intrusiva Alumiador e Vulcânica Serra da Bocaina. A suíte vulcânica é caracterizada nas serras de São Francisco e Bocaina, constituída dominantemente por termos de composição álcali - riólitos a riólitos, incluindo em menores proporções riodacitos, andesitos e dacitos. É constituída por uma diversidade textural de rochas subvulcânicas, vulcânicas e variedades vulcanoclásticas. Os depósitos piroclásticos de maior expressão são constituídos por partículas piroclásticas imersas em matriz afanítica de granulometria fina ou amorfa, onde se pode distinguir quartzo, feldspato, clorita, sericita, micrólitos de carbonato, esferulitos esparsos e vidro vulcânico reliquiar. As rochas piroclásticas são representadas por brechas, tufos, ignimbritos, aglomerados, lapilitos e púmices, contendo geralmente vitroclastos, litoclastos e cristaloclastos, púmices, fiammes, glass shards, esferulitos, vesículas e amígdalas. São rochas cálcio - alcalinas pertencentes à série de alto potássio de caráter predominantemente peraluminoso e definem magmatismo sincolisional e encontram - se geneticamente associadas à evolução do Arco Magmático Amoguijá. Palavras-chave: Maciço Rio Apa, Suíte Vulcânica Serra da Bocaina, litogeoquímica, petrografia.