Lunar Density Anomalies From a Flexible Gravity Inversion Approach
Abstract
Density anomalies in a planet or moon can be caused by impacts, circulation patterns of the mantle, primordial compositional differences, melting and other processes. Knowing the geometry and properties of these density anomalies could shed light into the processes that produced them and, ultimately, into the evolution of a body. Shallow density anomalies in the Moon have been explored extensively using high-resolution GRAIL gravity data and optimization-based inversion approaches based on spherical harmonics. Such inversions typically assume that the deepest signal comes from the Moho. In this work, we invert the spatial representation of the GRAIL data with a transdimensional Bayesian inference method to find density anomalies without the need for imposing prior constraints on their location or shape. We find a group of models fitting the gravity data that are consistent with the previously-mapped shallow lunar anomalies correlating with crater locations. Intriguingly, we also find deeper anomalies that do not correspond to specific surface features; these deep anomalies may have been mapped previously into the Moho relief. A limitation of our approach is that the retrieved density anomalies are not resolved at the same level of detail as those from more traditional approaches; however, our work has the advantage of providing quantitative information about the uncertainty and tradeoffs of parameters of the resulting density model. It also has the flexibility to allow additional constrains, such as rotational parameters, which would add detail to the density model of the interior.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMDI026..08I
- Keywords:
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- 1221 Lunar and planetary geodesy and gravity;
- GEODESY AND GRAVITY;
- 5430 Interiors;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5455 Origin and evolution;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 8147 Planetary interiors;
- TECTONOPHYSICS