Experimental deformation of dry Columbia diabase: Implications for tectonics on Venus

High-temperature creep experiments have been performed on samples of Columbia diabase to investigate the rheological behavior of rocks of basaltic composition under dry conditions. The effects of temperature, strain rate and oxygen fugacity on the creep strength were investigated. The activation energy for creep is Q = 500 ± 30 kJ/mol, and the stress exponent is n = 4.5 ± 0.3, indicating deformation controlled by dislocation creep. This rock was slightly weaker when deformed at oxygen fugacities set by an iron-wüstite buffer than by a nickel-nickel oxide buffer. The creep strength of our samples predried at 1000°C is significantly greater than values reported previously for samples deformed under as-received…