18-5 Ring Basin Formation and Evolution: Major Questions and Exploration Opportunities

Session: Surface Processes Across the Solar System

Presenting Author:

Debra Buczkowski

Authors:

Runyon, Kirby D¹, Buczkowski, Debra², Head, James³, Moriarty, Daniel⁴, van der Bogert, Carolyn⁵, Hiesinger, Harry⁶, Powell, Tyler⁷, Greenhagen, Ben⁸, Petro, Noah⁹

(1) Washington, , (2) Johns Hopkins APL, , (3) Brown University, , (4) University of Maryland at NASA Goddard Space Flight Center, , (5) University of Muenster, , (6) University of Muenster, , (7) Johns Hopkins APL, , (8) Johns Hopkins APL, , (9) NASA Goddard Space Flight Center, ,

Abstract:

We address outstanding questions regarding the structure, and evolution of peak-ring and multi-ring basins—some of the largest and most prolific geologic features on planetary surfaces, with a focus on the Moon’s Orientale basin. Despite numerous examples across the Solar System, fundamental questions remain about the mechanics of basin formation, the role of acoustic fluidization and/or dynamic fault-weakening, and how these processes are evidenced in the geologic record.

We present a new, high-resolution (1:200,000) geologic map and cross-section of the Orientale basin, integrating field observations, drill core data, remote sensing, gravity data, and numerical simulations. This comprehensive approach identifies pristine impact melt locations for future sampling and provides a conceptual model for multi-ring basin structure and formation. Our cross-section highlights persistent knowledge gaps in impact mechanics, excavation depth, transient crater dynamics, ring formation, melt generation and fate, and post-impact modification, including volcanic and geothermal processes.

We outline six major knowledge gaps: (1) the influence of bolide size, composition, and impact angle; (2) energy partitioning among melting, ejection, and deformation; (3) excavation depth and stratigraphic exposure; (4) the fate and chronology of impact melt; (5) short-term modifications such as terracing and uplift; and (6) long-term modifications including relaxation, volcanism, and subsequent impacts.

We use terrestrial analogs (Haughton, Chicxulub, Ries) to infer subsurface structures and processes for Orientale. The lack of a unified model for ring basin formation is emphasized, underscoring the need for multidisciplinary investigations. Future research directions include continued field mapping of central uplifts, finite element (as opposed to hydrocode) numerical modeling, laboratory experiments using artificial acoustic fluidization, and targeted lunar missions with drilling and geophysical imaging capabilities.

 

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