ANÁLISE PETROGRÁFICA DE ARENITOS DA FORMAÇÃO RESENDE (BACIA DE RESENDE, RJ)

This paper presents petrographic analysis of sandstones from Resende Formation collected in outcrops in the Resende Basin (Continental Rift of Southeastern Brazil), including: a) provenance informations based on mineralogical characterization, contributing to a better understanding of the depositional model, and b) textural and porosity characterizations, as a basis for discussions about the permoporosity properties of these deposits, which are important regional aquifer. The sandstones are predominantly classified as arkoses and, less abundant, as subarkoses and lithic arkoses. Quartz is the most abundant mineral in most samples, occurring as quartz monocrystalline and polycrystalline. The feldspars (microcline and orthoclase, predominantly, and plagioclase) are also quite abundant. In all outcrops studied were found plutonic litoclasts. As for provenance, we identified a mixture of source areas, but with significant participation of elements derived from plutonic rocks that outcrop at south of Resende Basin, confirming that the drainage systems from the southern edge of the basin had an important contribution to its sedimentary fill. Regarding the permoporosity properties, it can be concluded that the Resende Formation sandstones have good porosity, but with low connectivity due to a high concentration of infiltrated clay matrix, which obliterates the intergranular porosity. The porosity of secondary origin (intragranular, moldic and clay contraction) is more abundant.