Crater ice deposits near the south pole of Mars

Abstract

Layered deposits atop both Martian poles are thought to preserve a record of past climatic conditions in up to three km of water ice and dust. Just beyond the extent of these south polar layered deposits (SPLD), dozens of impact craters contain large mounds of fill material with distinct similarities to the main layered deposits. Previously identified as outliers of the main SPLD, these deposits could offer clues to the climatic history of the Martian south polar region. We extend previous studies of these features by cataloging all crater deposits found near the south pole and quantifying the physical parameters of both the deposits and their host craters. Using MOLA topography data, MOC and THEMIS imagery, and SHARAD radar sounding data, we characterize the distribution, morphology, and structure of the deposits. In addition, we examine the effect of the crater microenvironment on the formation and persistence of these deposits, exploring the relative importance of solar and eolian processes in shaping their present-day distribution and appearance. We consider the possibility that crater sand dunes may have promoted ice accumulation over time and weigh various explanations for the origins and larger climatic significance of these features.