The Probabilistic Determination of Lunar Subsurface Fault Structure Across the Mare Crisium by Very Fast Simulated Annealing (VFSA) Approach

Faults are common geologic features on celestial bodies, including the Moon. Due to the impact cratering process, many faults on the lunar surface are poorly preserved, with the subsurface structures holding the key to understand the ancient geological history and tectonic activity and evolutionary mechanisms instead. The subsurface density distribution allows the investigation of their dynamic characteristics, geologic context, and chronology. By utilizing the very fast simulated annealing (VFSA) method, we navigate the challenges of noise contamination and the complexities of solving nonlinear multiparameter problems to probabilistically identify the subsurface fault density structure of a possible buried graben across the Mare Crisium by gravity inversion. The inferred 3-D density anomalies verify the coexistence of large-scale mantle undulation and discrete high-density intrusions. It is hypothesized that the subsurface fault was formed after the mantle uplift, and the igneous intrusion through the graben was not influenced by the flexural stresses. Both of them contribute to the formation of mascon.