Modeling Lake Bonneville Paleoshoreline Erosion at Mars-Like Rates and Durations: Implications for the Preservation of Erosional Martian Shorelines and Viability as Evidence for a Martian Ocean

Mars may have had an ancient ocean filling its northern lowlands until around 3.5 billion years ago. The existence or lack of such a large body of water would have important implications on the ancient martian climate, landscapes, and habitability. One proposed piece of evidence is preserved paleoshorelines on the martian surface along the dichotomy boundary. Paleoshorelines on Earth are often recognized as subtle breaks in slopes that are laterally persistent and at consistent elevations. Is it probable, or even possible, that paleoshoreline topography on Mars might persist for 3.5 billion years, even at the slow erosion rates estimated for the martian surface? Here, we use topographic data showing well-preserved Earth-analog erosional paleoshorelines from Lake Bonneville in modern day Utah and numerically model their erosion at Mars-like rates for 3.5 billion years. Depending on the chosen diffusivity value and scale of the terrain used in each experiment, identifiable paleoshoreline features may or may not persist after the modeled erosion; higher diffusivities and smaller scales favor paleoshoreline erosion and smaller diffusivities and larger scales favoring paleoshoreline preservation.