Abstract
This paper is a contribution to the geology of the Cerquilho county (125 km²), state of Sao Paulo, Brazil, which is located at the center-east of the state, 160km from the city of Sao Paulo. The main purpose of this research was to get geologic and lithologic maps of the area, at a 1:50.000 scale, as a contribution to a better understanding of ground water distribution. Water from wells is urgently needed to the municipality supply. Late Carboniferous to Permian 550m thick Itarare Formation is the main stratigraphic unity in extension and in thickness. Less developed are the Permian Tatui and Irati formations. Latest Jurassic to Earliest Cretaceous tholeitic diabase intrusions, as dyke and sills cut these formations. Along some of the river valleys developed narrow alluvial deposits. The main lithologies of the ltarare Formation are diamictites (some true tillites), sandstones and siltstones. They are highly variable in distribution, interfengering each other vertically and horizontally. Coal seams are distributed mostly in the upper beds of this formation.
Highlights
Late Carboniferous to Permian 550m thick Itararé Formation is the main stratigraphic unity in extension and in thickness
The main lithologies of the ltararé Formation are diamictites, sandstones and siltstones. They are highly variable in distribution, interfengering each other vertically and horizontally
The 60m thick Tatuí Formation resting on the Itararé, is made up ofbrown variegated siltstones and some fine sandstones with less developed carbonate levels
Summary
Este trabalho apresenta os resultados obtidos com o mapeamento geológico do município de Cerquilho, realizado pelo Instituto Geológico em face da solicitação da Prefeitura local. O município de CerqulIho situa-se acerca de 160km de São Paulo, compreendendo uma área de aproximadamente 125km (Fig. 1). Embora inúmeros trabalhos tenham enfocado a complexidade estratigráfica do Grupo Tubarão (SOARES et alii, 1977; IPT, 1981; PETRI & FÚLFARO, 1983; entre outros) esta pesquisa não teve por objetivo estabelecer uma subdivisão estratigráfica da unidade, mas elaborar os mapas geológico (Fig. 1) e litológico (Fig. 2) da área, ambos na escala 1:50.000. Neste último procurou-se delimitar e caracterizar os litossomas componentes das unidades presentes, além de determinar seu posicionamento estratigráfico, com a finalidade de obter informações sobre a geometria dos corpos litológicos que possam constituir importantes aqüíferos
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