Formation of Cones within the Zhurong Landing Area

On May 15, 2021, China’s first Mars exploration mission, Tianwen-1 (TW-1), successfully landed its Zhurong rover in the southern Utopia Planitia on Mars. Pitted cones, a characteristic feature of both Utopia Planitia and the landing area, play a pivotal role in understanding the local geological processes. We conducted a detailed investigation into the spatial distribution, morphological characteristics, and morphometric parameters of these cones to uncover their origins. Using High-Resolution Imaging Camera images collected by the TW-1 orbiter, we identified 272 well-preserved circular cones in the landing area. High-resolution topographic analysis show that the cone heights range from 10.5 to 90.8 m, and their basal diameters range from 178.9 to 1206.6 m. By comparing the morphometric parameters of these pitted cones with similar features on both Earth and Mars, we identified them as mud volcanoes and a subset of igneous conical features. However, the spatial analysis results favor these cones as mud volcanoes. Additionally, the lower thermal inertia of these conical features compared to surrounding materials is a typical characteristic of mud volcanoes. Based on these evidence, we interpret the conical landforms in the TW-1 landing area as mud volcanoes.

The alignment of these mud volcanoes and their elongated vents orientation suggest a direction of maximum horizontal stress during their formation. This direction is consistent with nearby troughs, indicating that the mud volcanoes may have formed as a result of fracturing at the lower parts of these troughs. Through self-similar clustering analysis, we estimate the depth range of the mud source to be ~0.6-7.2 km. Based on the crater size-frequency distribution, the age of the mud volcanoes is limited to the middle to late Amazonian (~2.0 Ga - 400 Ma). These features suggest that the mud volcano cones in the landing area likely formed under volcanic destabilization conditions. Combining stress analysis with age data, we hypothesize that the formation of these mud volcano cones may have been influenced by basin subsidence and volcanic activity in the Elysium region. This study demonstrates the feasibility of using principal stress analysis to study Martian mud volcanoes, and offers insights into active geological processes on Mars during the Amazonian period.