Volcanic Processes in the Gassendi Region of the Moon

The lunar floor-fractured crater Gassendi and surrounding area were examined with high-resolution Lunar Reconnaissance Orbiter imagery and other remote sensing data to characterize and understand the volcanic processes in the southwestern region of the Moon. This study was selected because the Gassendi region exhibits a variety of volcanic features (e.g., cryptomaria deposits, pyroclastic deposits, maria, and lava lakes) and team participants have studied this region for 30 years (Hawke et al., 1991, ). This study confirms the existence of a previously identified cryptomare deposit and identifies an additional cryptomare deposit west of Gassendi crater and a pyroclastic northeast of Gassendi. Spectral and geochemical anomalies associated with dark-haloed impact craters reveal cryptomaria deposits in the western Gassendi crater floor and previously unmapped mare basalt within northeastern Gassendi. We identified three separate lava lakes on the northeast, northwest, and southwest floor of Gassendi crater based on morphology analogous to terrestrial lava lakes, geochemical signatures, and digital terrain data. Crater count (model) age data suggest that the lava lakes were active at similar to 3.6 Ga (300 Ma after floor emplacement). Criteria used to identify lava lakes in Gassendi were applied globally to locate candidate lava lakes within floor-fractured craters. With the identification of lava lake morphology, both in Gassendi crater and in other floor-fractured craters, the current ascent and eruption models should be revised to allow for at least short-term connection between magma supply at depth and surface lava lakes. Hence, this integration of multiple perspectives afforded by recent remote data sets reveals new views about lunar volcanic processes.