Potential formational scenarios of the mud volcanoes in the Zhurong landing area in Utopia Planitia, observed by Tianwen-1

Abstract

The widely distributed pitted cones in Utopia Planitia have several explanations, and they have been interpreted as mud volcanoes in the Zhurong landing area. The morphology and distribution characteristics of mud volcano cones can serve as indicators of stress direction and can also be used to calculate potential depth for mud sources. This information may assist in elucidating the potential formational scenarios of the mud volcanoes, which is of great significance to study the tectonic evolution in Utopia Planitia and possible water ice depths. The digital orthophoto map (DOM) and the digital elevation model (DEM) with spatial resolutions of 0.7 m and 3 m obtained by High Resolution Imaging Camera (HiRIC) from Tianwen-1 show that the mud volcanoes are distributed as both isolated cones and clustered cones in the Zhurong landing area. The age of the mud volcanoes is limited to the middle to late Amazonian (∼2.0 Ga - 400 Ma) based on the crater size-frequency distribution (CSFD); the depth range of the mud source is estimated to be ∼0.6–7.2 km by self-similar clustering analysis. The orientations of the aligned cones and the elongated mud vents indicate that the maximum horizontal stress (S_H) directions during the formation of the mud volcanoes in the landing area are in the direction of N67°E, which is in good agreement with the orientations of the nearby troughs, suggesting that the formation of the mud volcanoes in the landing area may have been controlled by the fracturing of the lower part of the troughs. These features, compared with those reported in previous study of mud volcanism/cone morphology on Mars, collectively suggest that the mud volcanoes in the landing area may have formed in a geological scenario under conditions of volcanic destabilization. Further, the formation of the mud volcanoes, with the analysis of the S_H, may have been influenced by both basin subsidence and the volcanism in the Elysium region. This study provides a new example of Martian mud volcano geologic formation scenarios, offers the feasibility of using the S_H to analyze Martian mud volcano formation, and hints at active geologic phenomena on Mars during the Amazonian period.