Decameter thick remnant glacial ice deposits on Mars

Abstract

Abstract On Mars, a smooth, draping unit—the “latitude‐dependant mantle” (LDM), believed to comprise meter thick layers of dust and ice—extends from the midlatitudes to the poles, covering at least 23% of the surface. We show that the LDM can be 30 m deep on pole‐facing crater walls, and by measuring the erosional and depositional volumes of small gullies that incise these LDM deposits, we show that it must contain between 46% and 95% ice by volume. Extrapolating to a global scale, these deposits account for ~10 4 km 3 of near‐surface ice, doubling previous LDM volume estimates. Thick LDM deposits can be emplaced during the many orbital variation‐driven climate excursions that occurred during the Amazonian period. We suggest that LDM deposits are similar to ice sheets composed of massive ice with a surface lag.