The formation of impact basins played a dominant role in the evolution of ancient planetary crusts. Despite their importance, the formation of large basins, and especially the transition from peak-ring to multiring basin morphologies, is poorly understood. The prevalence of impact craters on the Moon and wealth of geophysical data present an opportunity to better understand basin formation and the peak-ring to multiring basin transition.

Hertzsprung Basin, the smallest basin classified as a multiring basin on the Moon, has a distinct inner depression and 3 rings at 256 km, 408 km, and 571 km in diameter. Freundlich-Sharonov, the largest identified peak-ring basin, is slightly smaller with a peak-ring at 200 km and an outer ring at 582 km diameter. We consider both basins to be at the transition between peak-ring and multiring basins. However, the factors governing which type of basin forms at transitional sizes remain poorly understood. By modeling the formation of Hertzsprung and Freundlich-Sharonov basins, which are similar in size and location on the Moon,  we have a valuable opportunity to test how various planetary conditions can affect multiring and peak-ring basin formation. Through this work, we have begun to understand how crustal thickness and thermal gradient affect crater development at the Moon, and future work will look closely at how the bench structure relates to inner ring fault formation.

Collaborators:  This work is led by Brown DEEPS graduate student Evan Bjonnes in collaboration with Brandon. C. Johnson and Jeffrey C. Andrews-Hanna