Evaluation of small-sized mounds formation mechanisms in China's Zhurong landing region

Tianwen-1 is China's first independent Mars exploration mission. The rover "Zhurong" landed in the southern Utopia Planitia where various landforms such as impact craters, pitted cones, troughs, and aeolian features are present. In this study, we identified a special type of small-sized mounds in the Zhurong landing region using high-resolution images acquired by the Tianwen-1 orbiter. We made a detailed investigation on the morphology of the small-sized mounds as well as pits occurring on them. The small-sized mounds are usually <10 m in height and 50-150 m in diameter, while the pits are-45 m in width and-3.4 m in depth. By comparing with landforms of similar appearance, e.g., mud volcanos, ring-molded craters (RMCs), pingos, pedestal craters, and lava domes, we suggest that the small-sized mounds are most likely to be lava domes in origin due to similarities in the shape and rocky materials of the mounds. The pits spatially associated with the mounds are likely to be generated by the sublimation of subsurface volatiles after the formation of the mounds. This study provides additional interesting targets for the future exploration of the Zhurong rover to reveal the magmatic activities and volatile distribution and circulation in the Utopia Planitia.