Deciphering Water and Climate History in Lyot Crater, Mars: A Morphological and Mineralogical Perspective

Lyot (50.8°N, 330.7°W), the largest and deepest impact structure on the northern plains of Mars, with an approximate diameter of 220 km, is a prominent peak-ring crater situated near the hemispheric dichotomy within the Vastitas Borealis region. This Amazonian-aged crater has long fascinated due to its potential association with past hydrologic activity. Previous studies have suggested that the Lyot impact may have breached the cryosphere, enabling the release or exposure of subsurface groundwater. As a result, the crater interior and its surroundings preserve geomorphic signatures of both ancient and relatively recent water-related processes, including groundwater upwelling as well as atmospheric precipitation.

The primary objective of this study is to systematically map and characterize the major morphological features and mineral assemblages within Lyot Crater to better understand its hydrologic and climatic evolution. For this purpose, we employ a multi-instrument dataset comprising MOLA blended DEM for topographic analysis, Context Camera (CTX) imagery (5–6 m/pixel) for regional geomorphologic mapping, and select high-resolution HiRISE images (25–30 cm/pixel) for detailed surface feature interpretation. Mineralogical information is derived from CRISM observations (18 m/pixel), enabling the detection of key alteration minerals. Our geomorphic analysis identifies a diverse suite of features including fluvial channels, distal ridges, glacial and periglacial landforms, and multiple dune fields. Spectral analysis reveals the presence of Fe/Mg-smectites, chlorites, illite/muscovite, prehnite, and other hydrated minerals distributed across the central peak ring, crater floor, and rim. Together, these features and mineral signatures highlight the complex interplay of fluvial, glacial-periglacial, and aeolian processes that have shaped Lyot over time. While hydrous minerals and water-related landforms provide important clues to subsurface water activity and Mars’ broader hydrologic evolution, the aeolian deposits record more recent atmospheric dynamics and ongoing topographic changes. Overall, this integrated investigation enhances our understanding of Lyot Crater as a key site for reconstructing Amazonian-era water activity and climate transitions on Mars.