A MORPHOLOGIC COMPARISON OF SMALL VENUSIAN EDIFICES TO TERRESTRIAL MONOGENETIC VOLCANOES: POSSIBLE IMPLICATIONS FOR IDENTIFYING AND INTERPRETING SMALL SHIELD VOLCANOES ON VENUS

Small volcanic edifices (also referred to as small shields) are an abundant landform on Venus and their size and general shape suggests they could be analogous to monogenetic volcanoes on Earth. To better understand any similarity between volcanoes on these two planetary bodies, however, requires further constraints on their morphometric properties. With the goal of better understanding the geometry of small venusian edifices (as reported by Nypaver et al., 2018 and Lang et al., 2020; n = 39 edifices), we have compared their heights, radii, volume, and summit crater diameters to three types of terrestrial monogenetic volcanoes (as reported by Pike, 1978) that have been proposed as possible analogs to small venusian edifices – cinder cones, low shields of the Eastern Snake River Plain (Idaho, USA), and Icelandic shields. Our results show small venusian edifices tend to be narrower (~1 to 5 km) and taller (<100 m up to ~800+ m) than low and Icelandic shields and have average slopes (<5° to >30°) between those of cinder cones and Icelandic shields, though errors with identifying the bases of venusian edifices adds uncertainty to width and slope measurements. The volume of small venusian edifices (~0.01 km³ to >10 km³) is similar to both low and Icelandic shields and their basal areas are most similar to low shields (~1 to 10 km²). Summit crater widths range from ~0.5 to ~1.5 km, which are similar to those of low shields; w_crater/w_cone vs. cone width values are also similar to low shields. When taken together, our results suggest that small venusian edifices are most closely similar to both low and Icelandic shields and characteristics of both volcano types should be taken into account when interpreting the small volcanic edifices on Venus. Our results also suggest that the identification of small venusian edifices in a radar image may not be entirely dependent on image resolution but may also be influenced by surface roughness, edifice slope, and incidence angle. Observations of small venusian edifices from data returned from upcoming missions to Venus will allow for further characterization of these features and may reveal them to occur in a greater abundance than currently observed, especially if imaged with incidence angles similar to or larger than that of NASA’s Magellan mission.