Integration of Spectral Datasets and Radargrams in Mawrth Vallis, Mars

This study developed and applied an integrated framework to analyse surface mineralogical variability and radar backscatter response in Mawrth Vallis, Mars. The primary goals were to evaluate the lateral extent and potential subsurface continuity of phyllosilicate-bearing layers, and discussing the benefits, limitations and improvements for this approach. The methodology combined HRSC imagery, both color mosaics and digital terrain models to map four distinct surface units (S1, S2, S3, and DT) based on hue, brightness patterns, and topographic context. This was complemented by OMEGA and CRISM HSP hyperspectral data to characterize the regional distribution and composition of hydrated mineral phases, specifically Fe/Mg- and Al-phyllosilicates. Finally, SHARAD radargrams were used to identify clutter patterns, possible subsurface reflectors, and to analyse radar backscatter variations across the mapped surface units.

Spectral analysis confirmed that surface units mostly but not completely match the compositional boundaries, with S2 consistently shows dominant Fe/Mg-smectite absorptions, S1 exhibits Al-smectite features in a mixed spectrum, and S3 is characterized by dominant kaolinite absorptions. While these mineralogical variations generally align with the mapped surface units, small-scale heterogeneities suggest a finer stratification that is not fully resolved at the current data resolution.

SHARAD radargrams revealed variations in radar backscatter that are dependent on surface unit type. The DT unit consistently produces strong surface echoes, even in areas with similar terrain characteristics, which points to variations in the dielectric properties of the materials. In contrast, S2 returns weaker radar signals, consistent with the relatively lower dielectric constant of Fe-smectite. S1 exhibit intermediate radar responses. Additionally, potential subsurface reflectors were identified beneath the DT-S3 interface along Mawrth Vallis' southern flank, which may represent preserved stratigraphic interfaces, likely due to dielectric contrasts between the regolith-like DT material and the kaolinite-rich S3 unit.

This integrated approach highlights both the synergies and challenges of using multiple datasets for interpretation. Spectral data are effective for constraining surface composition but lack the ability to probe depth, while radar instruments can detect subsurface structures but struggle with thin layering and strong clutter patterns.