The Rümker region (41–45°N, 49–69°W) is located in northern Oceanus Procellarum of the Moon. Mons Rümker is the most distinctive geological feature in the area. The region is characterized by prolonged lunar volcanism (Late Imbrian Period to Eratosthenian Period), forming multiple geologic units in the area, including very low‐Ti to low‐Ti mare basalts, high‐Ti mare basalts, and volcanic complexes. Each geologic unit has distinct element composition and mineral assemblages. The Rümker region, overlying the Procellarum KREEP Terrain, was selected as the landing region for China's Chang'E‐5 lunar sample return mission. Prelanding analyses of the geologic context and scientific potential are reported in this contribution. We conducted detailed geological mapping using image, spectral, and altimetry data. Fourteen geological units were defined, a geologic map was constructed, and the geologic history was outlined. The western mare units (Im1, Im2, and Im3) are Imbrian‐aged (~3.4–3.5 Ga) representing the major stage of lunar mare eruptive volcanism. The eastern young mare units (Em3 and Em4; <2 Ga) are among the youngest mare basalts on the Moon. They have never been explored in situ or studied in the laboratory. We suggest that samples returned from the eastern mare unit (Em4) could answer many fundamental questions and that this unit should be listed as the top priority landing site for Chang'E‐5 sample return mission.
We used imaging, laser altimeter and thermal infrared data to map a 0.5 by 0.5° area containing the landing site of the Zhurong rover of the Tianwen‐1 mission. We analyzed the regional topography and thermophysical characteristics, and identified and characterized cones, impact craters, polygonal troughs, ridges and aeolian bedforms. An absolute model age of 757 ± 66 Ma was obtained for the major unit dominating the study area, younger than previous geological mapping results. We propose several targets of high scientific interest for Zhurong and a stratigraphic model composed of five layers (from bottom to top: Noachian basement, Early Hesperian volcanic ridged plains, Vastitas Borealis Formation materials, rocky materials and loose materials). The geomorphic features identified, the proposed stratigraphy and the regional geological evolution scenario set the stage for the Zhurong rover to continue to carry out its exploration of Mars.
12 July 2017 in Journal of Geophysical Research: Planets
Wind‐eroded ridges known as yardangs are common in most arid desert regions on Earth, as well as on other planets, notably in the Medusae Fossae Formation (MFF) and Gale Crater on Mars. However, the formation and evolution of these various yardangs are not well understood, which, therefore, requires further studies by more terrestrial analogues. Here we report a detailed investigation of the terrestrial yardang fields in the Qaidam Basin, northeastern Tibetan Plateau, China. Most of them are distributed in the northwestern and central eastern parts, with dominant orientations northwest to north‐northeast and approximately west to east, respectively. Based on their morphologies and distributions, yardangs within the Qaidam Basin have been classified into 11 different types out of four main groups. Wind is the dominant driver of yardang erosion, but water, salt, and mass wasting may also have played important roles in their formation and modification. A four‐step evolution model, including embryonic, adolescent, mature, and receding stages, is proposed to reveal their formation and evolution in the basin. Meanwhile, yardangs in the MFF and Gale Crater on Mars have morphologic and geometric characteristics that show striking similarities to those in the Qaidam Basin. The fact that some yardang fields in MFF on Mars also show overlapping relationships suggests that they possibly have experienced a multistage evolution, during which the evolution processes may have been interrupted at some stages due to differences in the competence of rocks and/or the changes of the environment.
Aqueous activities on Mars have gradually declined since the Noachian (>3.7 Ga). Although water can be stored in the subsurface during the latest epochs, geomorphological evidence is still limited. In this study, we used in situ imaging and spectral data acquired by China's Zhurong rover, as well as high‐resolution remote‐sensing data, to investigate the transverse aeolian ridges (TARs) in the Zhurong landing region of Utopia Planitia. A two‐stage evolutionary scenario of the TARs is proposed and polygonal features with hydrated minerals are identified for the first time on the surface of Martian TARs. We discussed the possible formation mechanisms of the polygonal features, and proposed that they could be related to recent aqueous activity and atmosphere‐surface water exchange on Mars, which sheds light on the hydrological cycle of Mars in current cold and dry climate.