Distribution and Morphology of Lava Tube Systems on the Western Flank of Alba Mons, Mars

Integrated analyses of Thermal Emission Imaging System (THEMIS) IR, Context Camera (CTX), and Mars Orbiter Laser Altimeter (MOLA) data sets have been used to characterize the western flank of the Martian volcano Alba Mons, which hosts a prominent population of lava tube systems. Identification and mapping of lava tube systems is based on both morphologic and topographic analyses, including the presence of chains of collapse depressions and elongate, sinuous ridges. Lava tubes and adjacent tabular lava flows with lengths of 100+ km form an extensive lava flow field. Analyses of topographic data sets, including slope maps, suggest continuity of the radial flow field pattern across the full western flank. Concurrent surface activity across the western flank is consistent with age constraints from geologic mapping and crater size‐frequency distributions that indicate Early Amazonian ages. The mapped population of 331 lava tube systems in the western flank geologic map quadrangle has a mean length of 36.2 km and a total length of ∼12,000 km. Individual lava tube systems extend up to ∼400 km. Orientation and slope data for lava tube systems show small deviations compared to regional values in 50‐km grid cells defined by the MOLA Digital Elevation Model, suggesting a strong coupling of lava tubes to the current slopes of Alba Mons. Mapping of lava tube systems documents segments both showing collapse and with no collapse, indicating the potential for extensive subsurface cavities that would be important astrobiological targets. Plain Language Summary This study uses imaging and topographic data sets acquired from spacecrafts orbiting Mars to study the western flank of the Martian volcano Alba Mons. Our research shows that the western flank of Alba Mons consists of a voluminous, broad lava flow field that appears to have formed at the beginning of Mars' most recent time period, approximately 2 billion years ago. Our measurements show that lava tubes and lava flows with lengths of 100 or more km form a prominent radial pattern within the flow field and follow current surface slopes. These lava tubes are characterized by chains of collapse depressions and/or locally high‐standing ridges. Alba Mons' lava tubes include both collapsed and uncollapsed segments. The presence of surface collapse as well as the newly documented potential for subsurface cavities of significant length suggests that Alba Mons' lava tubes may be important targets for assessing habitable enviro