Developing a Method to Quantify Seafloor Roughness

Seafloor roughness varies throughout the world's oceans and is primarily a function of initial spreading rate, off-axis volcanism, and sedimentation accumulation. Recent research involving deep-ocean circulation and seismic wave transmission indicate that knowledge of the seafloor roughness is very important; however, a detailed, quantitative measure of global seafloor roughness is not available. Previous studies have used either small "patches" of high-resolution bathymetry data or global compilations of low-resolution predicted topography data to measure seafloor roughness. While both of these approaches provide useful information, the high-resolution method has limited spatial coverage and the global compilation has limited resolution at important spatial scales. Our study attempts to combine both high-resolution patchy data with low-resolution continuous data to characterize or predict the full spectrum of seafloor roughness. The idealized approach involves taking data and applying a 2-Dimensional Fast Fourier Transform to assess seafloor roughness characteristics. The roughness spectrum is then compared with global estimates of spreading rates, sediment thickness, and anomalous volcanism. The high-resolution roughness spectra can also be combined with the low-resolution roughness spectra to give a more complete estimate of seafloor roughness. In our initial results we have observed the large impact of volcanism along the Darwin Rise and mid-Cretaceous volcanic zone in the Pacific, as well as relationships between spreading rate and sediment thickness in the Atlantic. In addition we have found that we can determine the orientation of the seafloor fabric with this method. Further work in the this study could lend us additional understanding of tectonic reconstruction, physiographic province characterization, as well as improved estimates of sediment thickness, seismic wave propagation models and ocean circulation models.