Surface and Near-Surface Volatile Suppression in 5 - 15 Kilometer Diameter Craters within Cabeus Crater Suggestive of Impact Gardening Dredge-Up Origin for Surface Ice Deposits on the Moon
Published in JGR - Planets, 2025
The water ice deposits at the lunar poles represent a unique scientific reserve, providing a window into the early history of water delivery to the inner Solar System. We identified five intermediate sized craters between 3-10 km in diameter within Cabeus crater that show evidence of volatile removal. All five craters are associated with low Water Equivalent Hydrogen (WEH) signatures relative to nearby locations with similar thermal profiles, and host no surface volatile detections. From the crater morphologies, the craters are likely to be Eratosthenian in age. In contrast, comparable older craters in the same region have WEH signatures consistent with their immediate surroundings, suggesting that surface volatiles and volatiles buried up to 1 meter below the surface in these craters have not been replenished in the past 1.1 - 3.2 Gy. We postulate that the impact events that formed these craters removed existing ice. While the older craters were then able to capture sufficient new ice to roughly equilibrate to their surroundings, the Eratosthenian craters were not exposed to a similar flux of incoming ice. This finding suggests that ice was captured in PSRs prior to the Eratosthenian era, providing a possible benchmark for the timing of true polar wander. Additionally, a spatial coincidence between low WEH signatures and a lack of surface deposits suggests that removal of buried water ice also results in the local suppression of surface ice. Surface water ice deposits may therefore be the product of impact gardening dredging up water ice buried below the surface.
Recommended citation: Luchsinger, K. M., Heldmann, J. L. & Colaprete, A. (2025). "Surface and Near-Surface Volatile Suppression in 5 - 15 Kilometer Diameter Craters within Cabeus Crater Suggestive of Impact Gardening Dredge-Up Origin for Surface Ice Deposits on the Moon" JGR - Planets. Submitted, Under Review 2025