| Abstract: | Carbonate rocks penetrated to a depth of 9.07 km in the Anadarko Basin of south-western Oklahoma, show a number of deformation features induced solely by the increased pressures and temperatures of deep burial. The rocks are at temperatures around 210° C and an overburden pressure of about 2.5 kb.Large calcite crystals in the limestones show extensive twin development accompanied by bending or multiple displacement along twin lamellae. Inferred granulation or cataclastic textures are shown by large calcite crystals which are now bordered by small anhedral calcite grains, a product of mechanical breakage. Pressure-solution features are common and aggrading recrystallization has led to an increase in average crystal size with depth.Limestones at these depths are tight compared to dolostones in the same basin at slightly shallower depths. These dolostones still retain in excess of 20% porosity at 8.08 km. |
