Relating Tectonic Spreading Rate to Crustal Roughness across a Tectonic Triple Junction Using High-Resolution Multibeam Sonar

Abstract

[Author's Abstract] Mid-ocean ridges, where magma is released to form new oceanic crust, can differ greatly in their shape depending on how quickly crust is produced and the complexity of the surrounding system of tectonic plates and plate boundaries. Several previous studies have determined an exponential relationship between the rate at which crust is formed and the physical roughness of the crust’s surface. In this study, I analyze bathymetric data taken aboard the R/V Thomas G. Thompson during the March 2012 School of Oceanography Senior Thesis Cruise at the Pacific-Rivera mid-ocean ridge, southeast of the Baja California peninsula, and determine that here, the surrounding crust is much smoother than what the published mathematical relationship between spreading rate and roughness would lead us to expect. I discuss several possible factors that might be influencing these results, including sediments being deposited on the ocean floor, the way in which oceanic crust cools over time, stresses from nearby plate movements, and questions about the mathematical methods that I and other scientists use to derive our results. Finally, I suggest instruments and methods that might improve the accuracy of future studies on the shape and speed of mid-ocean ridge spreading.