Formation constraints on Martian north polar volcanic edifices

Abstract

This study focuses on probable volcanic features in the north polar region of Mars in an effort to constrain their formation mechanisms and to estimate the thickness of a possible former ice sheet. Using Mars Orbiter Laser Altimeter (MOLA), High Resolution Imaging Science Experiment (HiRISE), Thermal Emission Imaging System (THEMIS), and Context Camera (CTX) data, we conduct topographic analyses of 108 putative volcanic edifices in the Borealis Volcanic Field within 69°N–81°N and 197°E–330°E. As it is rarely possible to identify rock types on Mars (such as hyaloclastite or palagonite), we are limited to the use of topographic data and images alone in our study. Therefore, we use available data for volcanic features in Iceland to predict the formational mechanisms of similar features on Mars. We examined 21 Icelandic volcanoes of subglacial and postglacial origin using Digital Elevation Models (DEMs) as well as limited differential GPS data and suggest by analogy that many of the features in the Borealis Volcanic Field were likely formed subglacially. We use these data to estimate a minimum ice sheet thickness for the area and suggest a range of minimum ice sheet thickness that varies between 57 and 610m with an average value of 283 m.