Evidence for Amazonian highly viscous lavas in the southern highlands on Mars

•We identified small-scale volcanic edifices in the martian southern highlands.•We conclude that these features were formed by viscous lavas.•Edifices represent martian equivalents of terrestrial lava domes and coulées.•Absolute model ages reveal Middle Amazonian volcanism in the martian highlands.

We have identified small-scale volcanic edifices, two cones and three domes with associated flows, within Terra Sirenum, a region situated in the martian southern highlands. Based on thermal, morphological, and morphometrical properties, and the determination of absolute model ages, we conclude that these features were formed by volcanic activity of viscous lavas in the mid-Amazonian epoch, relatively recently in martian history. If our hypothesis is correct, this small volcanic field represents rare evidence of young volcanic activity in the martian highlands in which martian equivalents of terrestrial lava domes and coulées might be present. On Earth, such landforms are usually formed by highly viscous evolved lavas, i.e., andesitic to rhyolitic, for which observational evidence is sparse on Mars. Hence, this field might be one of only a few where martian evolved lavas might be investigated in detail.