Identity and emplacement of domical structures in the western Arcadia Planitia, Mars

Abstract

Morphologic, morphometric, and thermophysical aspects of domical structures in a restricted part of the Mars northern plains were characterized using Mars Odyssey and Mars Global Surveyor data. The majority of domical structures consist of relatively high thermal inertia, subcircular to irregularly shaped “core' bodies surrounded by adjacent, relatively low‐albedo, low thermal inertia “annuli,” and dispersed aureoles of apparently disaggregated material. Core profiles vary considerably from low to high aspect ratios. Elongate “arms” of material extend from the central, summit regions in some of the structures. Core features include apparent blocky surface texture, summit fissures and pits, apparent summit and flank ruptures suggestive of “eruption” of material, and concentric and straight summit ridges. Core heights range from ∼30 to 400 m, mean = 160 m, diameters range from ∼620 to 3090 m, mean = 1550 m, aspect ratios range from 0.02 to 0.36, mean = 0.11, and volumes range from ∼0.1 to ∼1.8 km3. An additional morphologic type consists of subcircular, domical mounds that are apparently covered by plains materials. We propose that the majority of the structures are partially extrusive cryptodomes and lava domes, whereas the mounds are entirely intrusive cryptodomes.