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Call number: LD2668 .T4 1957 W54 / Master of Science

Volcanic rocks which outcrop over 40 sq. km in eastern Jersey and which have a maximum thickness of 25 km have been mapped in detail. Basaltic and andesitic lavas, tuffs and agglomerates, which have been affected by keratophyric alteration, are overlain by numerous ignimbrite cooling units, the youngest of which are generally aphyric, the oldest being porphyritic. Local rhyolites, tuf'fs and andesites occur among the igniinbrites. The volcanics are essentially conformable upon Brioverian sediments and are regarded as being late Precambrian in age. Cadomian E-W and N-B fold phases, with associated faulting, are largely responsible for the present outcrop pattern. The petrology and geochemistry of these volcanics have been studied. Together with the regional distribution of similar late Precambrian volcanism they indicate that the caic-alkaline suite was generated soon after the initiation of the global tectonic movements which eventually produced the Caledonides. The basalts and andesites are thought to result from the partial melting of a descending lithospheric plate within the mantle, the magmas thus produced being modified en route to the surface by fractionation and crustal contamination under a variable The rhyolitic maginas were produced by crustal anatexis and collected in high-level magma chambers prior to their eruption. Post.-orogenic Cadomian plutonics which invade the volcanics are also caic-alkaline but are chemically distinct from the extrusives. The petrology and geochemistry of a dyke swarm which invades the volcanics and just postdates emplacement of the plutonics is also discussed. This appears genetically related to the plutonic complexes and was generated close to the base of the crust.

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Orientador: Antonio Misson Godoy / Banca: Antonio Carlos Artur / Banca: Tamar Milca Bortolozzo Galembeck / Banca: Antenor Braga Paraguassu / Banca: Cláudia Lopes de Moura / Resumo: Os estudos da qualificação como material ornamental e para revestimento foram realizados em rochas graníticas porfiróides dos maciços São Francisco, São Roque, lbiúna, Piedade e Caucaia, tendo sido analisados os principais litotipos que apresentam exeqüibilidade de lavra. Objetivaram ampliar a oferta das rochas ornamentais no mercado nacional, com padronização das características tecnológicas de novas variedades e sua adequada identificação e tipificação quanto aos aspectos mineralógicos, geológicos, geoquímicos, tecnológicos (físicos-mecânicos) e de susceptibilidade ao ataque químico, possibilitando a prevenção de problemas arquitetônicos. Estas rochas apresentam características estéticas com ampla gama de variedades e são muito bem aceitas pelo mercado consumidor. Atualmente, sem os estudos técnicos específicos, ocorrem problemas tecnológicos de resistência no dimensionamento das placas decorrendo em maiores custos para o empresariado do setor. Aliados aos fatores estéticos que favorecem a sua utilização para fins ornamentais e de revestimento, encontram-se a distribuição geológica e geográfica nas proximidades aos maiores pólos consumidores, à cidade de São Paulo e aos portos exportadores. Os resultados obtidos nos ensaios tecnológicos das variedades mostram que os parâmetros analisados situam-se dentro dos limites padrões estabelecidos pelas normas para granitos utilizados como rocha ornamental e para revestimento, quer para ambientes interiores, quer para exteriores. / Abstract: Studies for qualificaton as dimension stones and covering materials were carried out in prophiritic granitic rocks from São Francisco, São Roque, Ibiúna, Piedade and Caucaia massifs had been analyzed the major lithotypes with plowing potential of rocks. Objectify to enlarge de offer of those rocks as dimension stones into the Brazilian market with the patterns of technological characteristics of new varieties and their adequate identifying and typifying on mineralogical, geological, geochemical, technological (physical and mechanical) and susceptibility to chemical attack aspects, making possible the prevention of architectural problems. Those rocks present esthetic characteristics with wide range of varieties and are very weill accepted by the consuming market. Actualy, without specific technicai studies, occur technological problems of strength in the sizing of tbe tiles or plates elapsing in more elevate costs for the sector companies. Allied to the esthetic factors that are favorable to the use of those rocks as dimension stones and covering materials are the geological and geographic distribution in the proximities to the greatest consuming poles, to the São Paulo city and to fim exporting harbours. Obtained results in the technological analyses of the varieties show that the parameters as sited into the limit standards established by the regulations for granites used as covering and dimension rocks, both for internal and external environment. / Doutor

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