Parâmetros de densidade de falhas e bandas de deformação em rochas siliciclásticas pouco consolidadas da Formação Resende, Eoceno, Bacia de Volta Redonda, estado do Rio de Janeiro

This study aimed to analyze density parameters of faults and deformation bands in siliciclastic rocks of the Resende Formation, taken as a geomaterial analogous to poorly lithified and fractured sandstone reservoirs. The study was initiated by the construction of a geological-structural section (scale 1:50) of an outcrop in the Volta Redonda Basin. This methodological stage was carried out with the help of a 2 by 2 meter mesh fixed on the outcrop. Based on the geological-structural section, a density map of deformation structures was created. After that, density parameters of deformation structures were measured applying linear scanlines and rectangular window sampling methods. The outcrop is composed by decimetric lenticular layers of stratified sandstones and conglomerates interbedded with tabular and lenticular layers of massive mudstones, with decametric thicknesses, with intervals of intraformational breccia. Two main NE-SW-striking normal faults (F1 and F2) with opposite dip directions were recognized, forming a graben. These main faults are associated with high density clusters of deformation bands and synthetic and antithetic faults. The density parameters revealed a lithologic control in the distribution of deformation structures. The highest density values are found in medium to coarse grained sandstones, while the lowest values are associated with clay-rich lithotypes, such as the mudstones, muddy sandstones and intraformational breccias. The density parameters showed greater deformation in the hanging-wall (graben), related to a more continuous structure distribution in this region.