Delta Deposits on Mars: A Global Perspective

Abstract

Deltas have long been considered a constraining element to reconstruct the water level of an ancient ocean that may have once occupied the northern lowlands of Mars, and recently this hypothesis started to be challenged. We investigate this hypothesis and present a global inventory of fan-shaped features showing typical deltaic traits across the entire Martian surface. For each element, we provide descriptive details and classifications based on morphology, location, and relation with characterizing environmental features. In this catalog of 161 deltas, we identified only six having high potential to constrain an oceanic paleoshoreline. Nonetheless, age and location of these candidates display discrepancies with what was previously suggested from independent data sets about shoreline age and locations. Our analyses hence indicate that deltas alone are insufficient to delineate a globally consistent ancient oceanic shoreline, but they have the potential to locally constrain the water level both in space and time.