The dependence of seafloor roughness on spreading rate

Bathymetric profiles taken parallel to flowlines across the mid‐ocean ridges of the South Atlantic and South Pacific strongly suggest an approximate linear relationship (slope 30–50 m cm −1 yr) between the RMS amplitude roughness of small scale features and spreading rate. This relationship is best demonstrated for spreading half rates <35 mm/yr. The RMS roughness‐spreading rate dependence is most clearly defined for that component of the ridge flank relief with spatial wavelengths of less than about 25 km. The RMS roughnesses calculated for constant spreading rate intervals of ∼10 my across a single flowline profile from the South Atlantic show that significant and consistent opposite flank roughness differences are typically associated with asymmetric spreading. This important observation has profound implications regarding the nature of the faulting and volcanic processes acting near the ridge axis to form the small scale asymmetric roughness.