Crater‐Exposed Mafic Materials in Chryse Planitia, Mars: Constraints on a Heterogeneous Sediment‐Mantled Subsurface

Abstract

Mafic minerals have been reported previously from impact craters in Chryse and Acidalia Planitia, but how these detections relate to crater structure, impact sampling depth, and the heterogeneous sedimentary cover of Chryse Planitia remains poorly constrained. Here we combine CRISM L‐detector observations, crater morphology, estimated excavation and structural‐uplift sampling scales, mapped geologic context, and ejecta mobility measurements to reassess crater‐associated olivine and pyroxene exposures across the Chryse Planitia. Mafic minerals are detected in multiple crater settings, including central structures, crater floors, crater walls, and ejecta blankets, indicating that olivine‐ and pyroxene‐bearing materials are not restricted to a single type of exposure. By comparing mineral occurrence with crater morphology and estimated sampling scales, we show that mafic‐bearing materials are exposed across a broad range of crater sizes and structural contexts, from shallow floor or wall exposures to deeper central‐structure settings. These relationships provide new constraints on the architecture of mafic‐bearing materials beneath the sediment‐mantled plains, while avoiding the assumption that detections define a simple continuous magma layer. Ejecta mobility values further indicate variability in target properties among layered‐ejecta craters, suggesting that the mafic‐bearing subsurface is physically heterogeneous as well as compositionally heterogeneous.