Ancient Martian volcanoes in the Aeolis region: New evidence from MOLA data

Mars Orbiter Laser Altimeter (MOLA) altimetric data confirm the volcanic origin of a Noachian-aged hilly feature (Zephyria Tholus) in the Aeolis area of Mars. Similar characteristics shared by at least one nearby topographic high suggest that volcanic activity represented by such features may have been more widespread than previously thought. Morphological structures and morphometric data for Zephyria are consistent with a stratovolcano origin, in which the edifice formed by mixed explosive and effusive eruptions, and was altered by subsequent flank erosion, to produce a distinctive truncated cone with concave upward flanks. Criteria are outlined to help detect and distinguish the origin of such features in other ancient regions of Mars.