As rochas intrusivas da Formação Serra Geral na Porção leste da Bacia do Paraná no Estado de São Paulo: Aspectos petrográficos e geoquímicos - Resultados preliminares

• Autor(a) principal: Machado, Fábío Braz [UNESP]
• Data de Publicação: 2005
• Outros Autores: Nardy, Antonio José Ranalli [UNESP], De Melo, Rodrigo Prudente [UNESP], De Oliveira, Marcos Aurélio Farias [UNESP], Squisato, Eloiza [UNESP]
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://www.periodicos.rc.biblioteca.unesp.br/index.php/geociencias/article/view/179; http://hdl.handle.net/11449/68610
• topic: Basalt; Diabase; Magma-types; Parana Basin; Volcanism Serra Geral; apatite; augite; geochemistry; igneous rock; magma; magnetite; petrography; pigeonite; plagioclase; quartz; Brazil; Campinas; Paulinia; Sao Paulo [Brazil]; South America; Eugenia uniflora

The purpose of this paper is to present preliminary aspects of the petrography and chemistry of intrusive rocks (sills and dykes) from the eastern portion of the Parana Basin in the State of Säo Paulo. Data from 80 samples of the region show a subaphyric and subophitic nature and have plagioclase (25-50%), augite (3-39%), pigeonite (0-10%) and magnetite (4-20%) as an essential minerals. Apatite and quartz are present as accessory minerals. The geochemical data of intrusive rocks show a basic to intermediate composition (48% < SiO 2 < 56%) and a high Ti nature (TiO 2 > 2%). Based on the minor and trace composition of the intrusive rocks, two different magma types were recognized, named Paranapanema and Pitanga. The spatial distribution of these magma types is not alleatory in the studied region. The intrusive rocks of Pitanga magma type are displayed in the Campinas-Paulinia region, while the Paranapanema magma type cover a large region above that one, between Rio Claro and Cajuru. Furthermore, the chemical composition of the lava flows of the Serra Geral Formation, sampled in this work, reveals a magma of Urubici type. So, the intrusive rocks of the eastern portion of the of State Säo Paulo are not the extension of the lava flows, or they aren't a portions which don't reach the surface.