MORPHOLOGIC CHARACTERISTICS OF EDIFICES IN THREE TERRESTRIAL BASALTIC VOLCANIC FIELDS: IMPLICATIONS FOR THEIR USE AS ANALOGS TO VENUSIAN SHIELD FIELDS

Basaltic volcanic fields (BVFs) on Earth have been postulated as analogs to clusters of small shield volcanoes (shield fields) on Venus. The extent to which terrestrial BVFs are similar to venusian shield fields, though, remains unclear. To begin testing the extent that terrestrial BVFs can serve as analogs to venusian shield fields, we compared edifices in the Cima, CA (n = 34 edifices); Pinacate, Mexico (n = 7 edifices); and Lunar Crater, NV (n = 21 edifices) basaltic volcanic fields on Earth to edifices in the Asherat (n = 2 edifices), Chernava (n = 6 edifices), Monoshi (n = 4 edifices), Nordenflycht (n = 3 edifices), Ran (n = 4 edifices), and Urutonga (n = 2 edifices) shield fields on Venus. Specifically, using Google Earth, we measured (where ‘good’ topographic data exist; to date, we have only been able to measure 62 total edifices between the three fields) the radius, height, and average slope of cinder cones in each of the three terrestrial BVFs, as well as the radius and depth of each summit pit; assuming a truncated cone, and subtracting the volume of the summit pit as a spherical cap, we calculated edifice volumes. We then compared these results to those collected for the six venusian fields by Nypaver et al. (2018; GSA Special. Paper 538). Our results show that, with the exception of edifice slopes, our measured terrestrial edifices represent a population distinct from the venusian edifices; edifice slopes are broadly similar between Earth and Venus. To elaborate, terrestrial edifices have basal radii ranging from <<0.5 km up to ~0.6 km, heights from ~10-200 m, slopes of ~5°-30°, and volumes of up to ~0.1 km³. In contrast, venusian edifices have basal radii from ~1.5-5.5 km, heights from ~50 m to ~1.5 km, slopes from ~10°-30°, and volumes of up to >90 km³. The larger heights, radii, and volumes (where there is an up to an order of magnitude difference) for venusian edifices is intriguing and suggests they could represent more frequent and/or longer-lived eruption cycles compared to terrestrial cinder cones, though environmental differences between the two planets need to also be taken into account. Ultimately, our results do not rule out that terrestrial BVFs can serve as valid analogs to venusian shield fields; however, use of terrestrial BVFs as an analog to venusian shield fields must account for these morphometric differences.