An explosive mud volcano origin for the pitted cones in southern Utopia Planitia,Mars

Pitted cones are cone-shaped structures,spanning from meters to kilometers in size,characterized by summit depressions.They are widely distributed on the surface of Mars with various origins,such as rootless cones,mud volcanoes,cinder or scoria cones,tuff rings or cones,pingos,and dirt cones.If the pitted cones identified in southern Utopia Planitia are mud volcanoes,as is speculated,they could be of particular interest due to the fact that mud volcanoes on Earth bring sediments from a depth of meters to kilometers to the surface.In this study,we have investigated the pitted cones near Zhurong rover’s landing site in southern Utopia Planitia,utilizing recent images and digital elevation models obtained from the High Resolution Imaging Camera instrument onboard China’s Tianwen-1 orbiter.By leveraging the high-resolution images and digital elevation models,we have conducted a geometric measurement to distinguish the origin of pitted cones in the vicinity of the Zhurong rover.The morphological characteristics of these pitted cones indicate an explosive mud volcano origin.These explosive mud volcanoes could have formed by the violent eruption of subsurface overpressurized sediments generated from the combined effect of overburden pressure and anomalous high heat flow.The sediments forming the pitted cones in the northern plains could be the remnants of an ancient ocean.With future in-situ observations of these pitted cones,we hope to gain further insights into the sediments of the putative northern ocean,as well as the physical and chemical properties of the Martian subsurface during the formation of the pitted cones.

Volcanism and Deep Structures of the Moon

Volcanism is the most important endogenic geological process of the Moon,which is closely related to its internal structure and thermal history.Lunar volcanism is one of the most important topics for lunar science and explorations.Recent lunar orbital observations,in situ explorations,and sample return missions have returned a new generation of high-resolution datasets,which greatly enriched our knowledge of lunar volcanism.Here,we summarize recent advances in the duration and spatial distribution of lunar mare volcanism,as well as origin of volcanic landforms such as lava flows,sinuous rilles,lava tubes,domes,and cones.We proposed several outstanding problems in the study of temporal and spatial span of lunar volcanism,the formation mechanism of the varied volcanic landforms,and their relation with deep structures.To solve these problems,more in situ explorations and sample return missions from various volcanic units are needed.

Subsurface Structures at the Chang'e-3 Landing Site: Interpretations from Orbital and In-Situ Imagery Data

The Chang＇e-3（CE-3） spacecraft successfully landed on one of the youngest mare surfaces on the Moon in December 2013. The Yutu rover carried by CE-3 was equipped with a radar system that could reveal subsurface structures in unprecedented details, which would facilitate understanding regional and global evolutionary history of the Moon. Based on regional geology, cratering scaling, and morphological study, here we quantify the subsurface structures of the landing site using high-resolution orbital and in-situ imagery data. Three layers of lunar regolith, two layers of basalt units, and one layer of ejecta deposits are recognized at the subsurface of the landing site, and their thicknesses are deduced based on the imagery data. These results could serve as essential references for the on-going interpretation of the CE-3 radar data. The ability to validate our theoretical subsurface structure using CE-3 in-situ radar observations will improve the methods for quantifying lunar subsurface structure using crater morphologies and scaling.