Mon: Poster Session & Social
Time: 23/Sep/2019: 4:30pm-6:00pm · Location: Tent in front of the castle/Schloss
Lunar gravity: Impact processes inform the density structure of the mare crust
1Solar System Exploration Division, NASA Goddard, Greenbelt, MD, United States of America; 2CRESST, University of Maryland Baltimore County, USA; 3Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI, USA
Recent improvements in Gravity Recovery and Interior Laboratory (GRAIL) modeling (Goossens et al., 2018; 2019 submitted) allow a closer look at the laterally variable density structure of the nearside lunar mare regions. Spectral analyses of gravity in highland regions exhibit nearly perfect correlation with topography at spherical harmonic degrees from 250 to beyond 900, corresponding to spatial scales < 12 km, but in most of the nearside mare and the interior regions of the farside South Pole-Aitken basin the correlations drop off substantially. Since these scales are only influenced by the shallow crustal density structure, we employ relatively fresh impact craters in the range of 3-5 km depth and16-130 km diameter as probes of mare density. Modeled gravity anomalies of these craters suggest an increase in density of 25-30% averaged over the crater depths between the excavated mare flow layers and the surrounding highlands. We interpret these results in the light of enigmatic quasi-circular gravity anomalies, in the southwestern Procellarum region for example, that have been suggested to arise from some combination of buried craters, volcanic intrusion and/or mantle uplift and crustal thinning.