Deformation bands in porous sandstone: case study in basins of northeast

Abstract

The meso and microscopic scale sandstonechar-acterizations of the deformation bands of three sedimentary basins in northeastern Brazil; the Po-tiguar and Sergipe-Alagoas basins (Brazilian Atlantic Margin) and the Tucano Basin (aborted rift basin) were compared for their similarities and differences.Deformation bands are structures commonly developed in porous sandstones that make up the main reservoir-rock in siliciclastic petroleum systems. These structures influence the permo-porous properties and consequently the migration pathway into a sandstone reservoir. To understand their formation process and development has been the focus of a great number of articles in recent petroleum geology literature. This study highlights the similarities and the differences in the features and deforma-tion mechanisms that provoked the development of deformation bands in the damage zones of major faults in three different sedimentary basins. In terms of basin tectonics, the deformation bands’ formation and geometric arrangements are associated with major structures. In the case of the Açu Formation, a correlation was observed with the dextral Afonso Bezerra fault system, whereas in the Sergipe-Alagoas Basin the normal dextral strike-slip faults can be associated with the faulting of the boarder basin. In the Tucano Basin case, the deformation basins are related to the Jeremoabo transpressional fault, a major structure a few kilometers to the north. This study applies structural geology tools to better understand the geometric arrangement and growing mechanisms of deformation bands in different lithological and tectonic settings. Although the deformation bands present a similar aspect in a macro-scopic view, the interplay between depositional and mineralogical parameters of the host rock, as well as the basin’s burial and tectonic history resulted in the development of different sandstone deformation bands in three northeastern brazilian basins.