Volcanic and impact deposits of the Moon's Aristarchus Plateau: A new view from Earth-based radar images

Lunar pyroclastic deposits reflect an explosive stage of the basaltic volcanism that filled impact basins across the nearside. These fine-grained mantling layers are of interest for their association with early mare volcanic processes, and as possible sources of volatiles and other species for lunar outposts. We present Earth-based radar images, at 12.6 and 70 cm wave-lengths, of the pyroclastic deposit that blankets the Aristarchus Plateau. The 70 cm data reveal the outlines of a lava-flow complex that covers a significant portion of the plateau and appears to have formed by spillover of magma from the large sinuous rille Vallis Schröteri. The pyroclastics mantling these-flows are heavily contaminated with rocks 10 cm and larger in diameter. The 12.6 cm data confirm that other areas are mantled by 20 m or less of material, and that there are numerous patches of 2 cm and larger rocks associated with ejecta from Aristarchus crater. Some of the radar-detected rocky debris is within the mantling material and is not evident in visible-wavelength images. The radar data identify thick, rock-poor areas of the pyroclastic deposit best suited for resource exploitation.