¹Inès Torres Auré, ^2,3John Carter, ¹Cathy Quantin-Nataf, ^2,4Damien Loizeau, ¹Erwin Dehouck, ¹Matthieu Volat
Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2026.117113]
¹Laboratoire de Géologie de Lyon : Terre, Planètes, Environnement (LGL-TPE), Université Claude Bernard Lyon 1, CNRS, Villeurbanne, France
²Institut d’Astrophysique Spatiale (IAS), Université Paris Saclay, CNRS, Orsay, France
³Laboratoire d’Astrophysique de Marseille (LAM), Université Aix-Marseille, CNRS, Marseille, France
⁴Qualisat, Bièvres, France
Copyright Elsevier

The Fe/Mg-phyllosilicate-bearing units at Oxia Planum and Mawrth Vallis, two key Noachian sites along the martian dichotomy, exhibit distinct compositions despite their proximity. Using novel spectral criteria developed in this study, we distinguish two clay types: Type-1 (Mg-rich smectites/Fe2+-bearing saponite/vermiculite) and Type-2 (Fe3+-rich nontronite). Hyperspectral (OMEGA/CRISM) and textural (HiRISE/CTX) analyses reveal a regionally extensive basal Type-1 unit continuous across both sites, overlain by a Type-2 unit limited to Mawrth Vallis and southeast of Oxia Planum (above main delta fan elevations). A cratered paleosurface, with a Type-1 spectral signature, marks their boundary, indicating a depositional hiatus. The Type-1 unit’s lateral extent (>600 km) and elevation range (>1300 m) suggest a large-scale aqueous process, while the Type-2 unit’s absence below Oxia Planum’s delta fan implies either post-depositional erosion or environmental controls during deposition at Oxia Planum. Our results constrain early Mars’ climate models, challenging localized deposition/alteration hypotheses and ocean scenarios. These findings reveal that Type-1 clays extend over a much broader area than previously assumed, indicating that the ExoMars Rosalind Franklin rover will not investigate a localized phenomenon but rather a process with significant regional–and potentially global–implications for the geological and climatic history of Mars.

¹Veronika Pazderová, ¹Pavol Matlovič, ^2,3Hadrien Devillepoix
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2026.117107]
¹Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynská Dolina, Bratislava, 842 48, Slovakia
²Space Science and Technology Centre, School of Earth and Planetary Sciences, Curtin University, Kent Street, Perth, 6102, WA, Australia
³International Centre for Radio Astronomy Research, Curtin University, Perth, 6845, WA, Australia
Copyright Elsevier

Meteor spectroscopy is a key method for probing the composition of meteoroids, providing insights into both their overall composition and the relative abundances of individual species. In this study, we present a comparison of meteor spectra recorded simultaneously from multiple observing sites within the Australian segment of the AMOS (All-sky Meteor Orbit System) network. We examine the origins of spectral discrepancies between the respective systems, considering factors such as focusing, spectrum extraction geometry, calibration, and observing geometry. This work represents one of the few detailed examinations of such effects. Our results show that factors such as observing geometry, focusing, calibration procedures, instrument characteristics, and specific data-processing approaches can introduce uncertainties in relative line intensities that are typically unresolved in conventional single-station observations. The four case studies presented in this work demonstrate that the sources of discrepancy in relative line intensities can be identified and potentially accounted for, ensuring that meteoroid composition estimates based on these intensities remain robust.