In Situ Observation of Weathering Rinds at the Zhurong Landing Site, Mars

Abstract

The Zhurong rover conducted in situ spectral investigations of southern Utopia Planitia, where the bedrock composition remains relatively unknown due to dust cover. Here we identify some spectrally distinct dark patches sporadically occurring on rocks by combining the Multispectral Camera and Short-Wave Infrared data. These dark patches represent relatively dust-free surfaces and exhibit concave-up blue slopes in the near-infrared not identified in that area from orbital data. This spectral signature is most consistent with silica-enriched leached rinds on basaltic glass. The presence of such weathering rinds could imply leaching in an acidic aqueous environment of igneous rocks previously transported to the landing site as impact ejecta or pyroclastic deposits by explosive volcanism. In situ observations link the dark patches to the northern low-albedo regions, suggesting that the surficial acidic weathering may be more widespread and occurred in the northern lowlands under Amazonian climatic conditions.