Abstract The study of Martian chaotic terrains helps constrain the ancient geologic history of the Martian water cycle, as these regions preserve geomorphic and mineralogical evidence of catastrophic groundwater release, subsurface ice melting, and associated aqueous processes active on the planet’s early history. This study presents a geomorphological and mineralogical analysis of Belén crater located in the northern region of Iani Chaos. By integrating high-resolution Context Camera and High Resolution Imaging Science Experiment imagery with hyperspectral data from the Compact Reconnaissance Imaging Spectrometer for Mars, we mapped the geological units and identified assemblages of hydrated minerals associated with potential past hydrothermal activity. These minerals are spatially correlated with distinct geomorphic units, distributed across the crater floor, central mound, and rim. Detected phases include polyhydrated sulfates and monohydrated sulfates. Additionally, phyllosilicates, including chlorite, were identified, along with hydrated amorphous phases such as opal. The spatial relationships and topographic position suggest that these hydrated minerals were emplaced through subsurface fluid circulation, likely triggered by impact-induced fracturing and geothermal heat. The co-occurrence of opaline and sulfate phases supports scenarios involving acidic aqueous environments and evolving water–rock interactions. We propose that Belén crater hosted a localized, postimpact hydrothermal system, where mineral deposition was driven by ascending fluids. These findings support a multiphase evolution of Iani Chaos, in which mineral deposition likely occurred through sustained, episodic processes rather than a single catastrophic event. This work contributes to understanding the mineralogical diversity and the potential habitability of chaotic terrains on Mars during its aqueous history.
Rojas et al. (Fri,) studied this question.