Lithofacies control on the formation of deformation bands; an example from the Sherwood Sandstone Group (Induan-Anisian, Lower Triassic) in western England

Deformation bands can affect the permeability within reservoir sand bodies, resulting in reductions in hydrocarbon flow and impacting recovery rates. This permeability reduction also impacts water extraction and limits contaminant dispersal. The occurrence of deformation bands is notably associated with high-porosity, clastic sandstones, which on a bulk scale often represent the better reservoir units in a succession, with elevated porosity and permeability characteristics. This study quantitatively evaluates the likelihood of nine individual lithofacies types of aeolian or fluvial origin hosting deformation bands using exposures of the Triassic, Sherwood Sandstone Group of northwestern England (United Kingdom). Specifically, this study determines that of the nine lithofacies types identified, the homogeneous, clean (silt/clay poor) sandstones formed by (aeolian) grain-flow and grain-fall processes are most prone to containing deformation bands. The genetically associated and lithologically similar interdunes are identified as the next most prevalent for hosting deformation bands despite an order of magnitude reduction in deformation band frequency when normalized to volumes of lithofacies present, relative to the aforementioned grain-flow and grain-fall lithofacies. Of the nine lithofacies types observed, all, with exception of aeolian grain-flow and grain-fall facies, were considered underrepresented relative to the total number of deformation bands observed at outcrop, with grain-fall and grain-flow facies at every locality hosting at least 85% of the deformation bands present.