Search

The successful return of lunar soil samples from the northern Oceanus Procellarum by the Chang'E 5 (CE-5) mission has provided unprecedented ground-truth information for the previously unexplored region of the Moon. In particular, the particle size and mineral constituents of the CE-5 soil samples are of critical importance to interpret remote sensing data. With a Raman-based particle analysis system, we show that the particle size properties and mineral constituents of the CE-5 soil can be simultaneously determined with a small sample size (ca. 30 μg). The CE-5 sample scooped from the lunar surface has an overall small size between 0.4 μm and 73.9 μm (mean=3.5 μm), and mainly consists of pyroxene (39.4%), plagioclase (37.5%), olivine (9.8%), Fe-Ti oxides (1.9%), glass (8.3%) and other minor or trace phases. The results are consistent with previous analyses with larger sample sizes. In addition to minimum sample consumption, this method requires very little sample preparation, and can rapidly build a large database with each particle precisely traceable. Therefore, this novel technique is particularly suitable for the analysis of future returned soil samples from extraterrestrial bodies. [ABSTRACT FROM AUTHOR]

The Ediacaran–Cambrian Phosphogenic Episode is the Earth's first true phosphogenic event and resulted in worldwide phosphate deposits, which occurred during the processes of the Neoproterozoic Oxygenation Event. The Ediacaran Doushantuo Formation (ca. 635–551 Ma) of Weng'an area in central Guizhou, South China, contains two economic phosphorite beds (the Lower and Upper Phosphorite Beds). This paper presents a detailed stratigraphic, sedimentological and mineralogical study of multiple outcrop and drill core sections of the Doushantuo Formation across the Weng'an area, and identified 11 lithofacies and 4 types of phosphatic grains. Significant differences in lithofacies and grain types between the upper and lower phosphate deposits are observed, indicating that the two sets of phosphate deposits are the products of two distinct phosphogenic processes. The Lower Phosphorite Bed mainly consists of banded and laminated phosphorites, contains micro-oncoids formed by microbially-mediated precipitation and peloids formed by in-situ chemically oscillating reactions, indicating a biochemical and chemical enrichment of phosphorus to sediments during the Early Ediacaran Period. The Upper Phosphorite Bed is mainly composed of carbonaceous, massive, and stromatolitic phosphorites, contains bioclasts (phosphatized spheroidal fossils), and intraclasts formed by hydrodynamic agitation, suggesting that the major accesses of phosphorus to sediments were the remineralization of organic P. Deposition of the two economic phosphorite beds was controlled by two sea-level cycles. Such differences have also been documented in contemporaneous phosphate-bearing successions in Brazil and Mangolia, indicating a significant shift in global phosphogenic mechanism during the early and middle Ediacaran, which may be due to the changes in redox conditions in seawater, associated with the Neoproterozoic Oxygenation Event. These regional active P-cycle processes could produce more free oxygen, which may have contributed to the upcoming Phanerozoic global oxidation. [ABSTRACT FROM AUTHOR]

The lunar regolith layer preserves abundant information on the internal properties of the Moon as well as the space-surface interactions. By gardening and overturning through time, the regolith layer is heterogenous and soils from different depths could record the complex evolution history of the Moon. Chang'e-5 (CE-5) successfully returned scooped samples and drilled samples from the northeastern Oceanus Procellarum of the Moon. In this study, one scooped sample (0–3 cm depth, S0) and two drilled samples (~10 cm depth, S10; and ~ 65 cm depth, S65) were employed to analyze their granulometry and mineralogy by micro Raman spectroscopy. The grain size increases with depth, and the median grain size of S0, S10, and S65 are Φ5.45 (30.2 μm), Φ4.47 (45.0 μm), and Φ3.37 (96.4 μm), respectively. Their mineral types and contents are pyroxene (33.4–40.5 vol%), plagioclase (30.4–33.8 vol%), olivine (9.0–13.1 vol%), glass (6.9–10.7 vol%), Fe Ti oxide (6.7–7.5 vol%), cristobalite (0.2–3.8 vol%), quartz (0.4–0.9 vol%), and phosphate (0.2–0.6 vol%). The size-dependent mineral modes reveal the relationship between grain size and mineralogy. The mineral modal abundances of 3 soil samples at different depths are roughly similar to that of CE-5 basalts. Raman peak position of quartz may record a peak shock pressure of 31.4 GPa. 5–9 vol% plagioclase amorphization reflects that at least 2–9% exogenous materials in CE-5 soil samples are ejected from craters with diameters larger than 3 km located beyond 50 km from the landing site. • Granulometry and mineralogy of CE-5 soil samples from three different depths were analyzed by micro-laser Raman spectroscopy. • The grain size distribution of CE-5 lunar soil exhibits an increasing trend with depth. • The mineral constituents of the soil samples are consistent throughout various depths. • Highly shocked materials were observed, including shocked quartz, quartz glass, and plagioclase glass. • Exogenous materials account for >2–9% of the CE-5 samples. [ABSTRACT FROM AUTHOR]