¹Deepali Singh,¹Priyadarshini Singh,¹Nidhi Roy,¹Saumitra Mukherjee
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114757]
¹School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India
Copyright Elsevier

The present study investigated an inter-crater depression, which is hypothesized to have been hydrologically active in the past. Mineralogical analysis of the putative lake was carried out to examine the presence of secondary minerals and decipher its aqueous alteration history. The basin was observed to be predominant in mono- and polyhydrated sulfates and hydrated silica with intermittent exposures of Al phyllosilicates such as montmorillonite and beidellite. Later, mineral profiling of the surrounding terrain was also carried out to infer the origin of these minerals. We recorded signatures of Mg-rich smectite (saponite) and Fe/Ca‑carbonate in crater rims and ejecta here, in addition to the minerals previously identified within the basin. Spectro-morphological examination of the entire region helped in understanding the emplacement of the minerals and construction of the life cycle of the lake. The contrasting environmental conditions required for the formation of these minerals suggest that the basin witnessed multiple hydrological cycles and that it was active for a long period of time. We propose the basin to be an endorheic playa with geologically complex terrain which may hold good biosignature preservation potential for future exploration missions. Finally, our preliminary exploration of the area highlights the importance of inter-crater depressions on Mars and their significance in water budgeting, even if a small percentage of them were hydrologically active.

¹Haijun Cao,^1,2Zongcheng Ling,¹Jian Chen,^1,2,3Xiaohui Fu,⁴Yongliao Zou
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13741]
¹Shandong Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Institute of Space Sciences, Shandong University, Weihai, Shandong, 264209 China
²CAS Center for Excellence in Comparative Planetology, Chinese Academy of Sciences, Hefei, China
³State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Taipa, Macau, China
⁴State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing, 100190 China
Published by arrangement with John Wiley & Sons

Lunar meteorite Northwest Africa (NWA) 11460 has been classified as a polymict breccia, composed of feldspathic clasts, mafic-rich clasts (gabbroic and troctolitic fragments), granulites, and a wide range of impact melt breccias and dimict breccias. The non-mare clasts have chemical affinities in major element composition to the Apollo ferroan anorthosites (FAN) and magnesian-suite plutonic rocks. In contrast, incompatible trace element (ITE) compositions of the Mg-richer clasts are more consistent with those of FANs rather than magnesian-suite rocks. NWA 11460 has a Mg-rich feldspathic bulk composition (FeO = 4.53 wt%, Al2O3 = 25.87 wt%, and Mg# = 73.8) and relatively ITE-poor (i.e., Th = 0.31 ppm and Sm = 0.65 ppm) characteristics. Feldspathic impact melt materials are approximately similar in composition to the estimated composition for the upper feldspathic lunar crust (as defined by Korotev et al., 2003). The ITE-poor and Mg-rich characteristics different from Apollo 16 feldspathic impact melts indicate that this meteorite has been possibly derived from a region distal to the nearside lunar highlands. Our analysis further suggests that NWA 11460 most likely originated from the farside of the Moon. Compositionally, Mg-rich ITE-poor clasts within NWA 11460 as well as those observed in other feldspathic lunar meteorites (which probably came from many different lunar regions) reveal that Mg-rich rocks with low-ITE components represent an important constituent of lunar crustal rocks. The diversities of highly magnesian non-mare clasts and the low-ITE chemistry provide geochemical clues for the genetic relationship between KREEP components and magnesian plutonic magmatism on the lunar farside.