Search Results (4)

High-resolution lunar gravity anomaly data are of great significance for the study of the lunar crust and lithosphere structure, asymmetric thermal evolution, impact basin subsurface structure and mass tumor genesis, breccia, and magmatism. However, due to errors in satellite orbit and instrument observation, correlation error in high-order spherical harmonic coefficients, and other factors, satellite observation gravity anomaly data present evident aliasing phenomena of stripe noise and random noise in the spatial domain, resulting in difficulties in practical application analysis. In this paper, a lunar satellite gravity anomaly denoising method based on prior knowledge deep learning is proposed. In one instance, the prior knowledge is fused into the data set, the manual processing results are labeled, and the six label-superimposed directions of the simulated stripe noise are used as the sample input data. Conversely, because the gravity field is a harmonic field with smooth characteristics, the Laplace constraint is added to the loss function, and the deep learning results are optimized through Gaussian filtering. Synthetic and real data tests demonstrate the effectiveness of the proposed method in removing complex noise from lunar satellite gravity anomaly data. Full article

We provide the first visible near-infrared (VNIR) reflectance spectroscopy characterization of a sample from the lunar feldspathic breccia NWA 13859. The sample is a 2 mm thick slab with an approximate area of 35 ± 2 cm². We characterized the spectroscopic variability by choosing and analyzing representative spots throughout the sample. Our results show a distinct spectral contribution from orthopyroxene, which, according to a preliminary mineralogical characterization, should be a minor phase in the sample. In a second step, we measured several spectra along a transect between a clast and the matrix. In order to oversample the signal, the points analyzed along the sample were partly superimposed to each other (80% areal superposition). The same approach was extended to a grid of points covering an area of about 8.6 cm², with the goal of obtaining a spatial resolution of the spectral parameters higher than the instrument’s spot size. Using this strategy, we obtained 2D maps of spectral parameters, which allowed us to infer the major mineralogical composition of the sample. Full article

A highly resistant mineral, zircon is capable of preserving information about impact processes. The present review paper is aimed at determining the extent to which Raman spectroscopy can be applied to studying shocked zircons from impactites to identify issues and gaps in the usage of Raman spectroscopy, both in order to highlight recent achievements, and to identify the most effective applications. Method: Following PRISMA guidelines, the review is based on peer-reviewed papers indexed in Google Scholar, Scopus and Web of Science databases up to 5 April 2022. Inclusion criteria: application of Raman spectroscopy to the study of shocked zircon from terrestrial and lunar impactites. Results: A total of 25 research papers were selected. Of these, 18 publications studied terrestrial impact craters, while 7 publications focused on lunar breccia samples. Nineteen of the studies were focused on the acquisition of new data on geological structures, while six examined zircon microstructures, their textural and spectroscopic features. Conclusions: The application of Raman spectroscopy to impactite zircons is linked with its application to zircon grains of various terrestrial rocks and the progress of the electron backscatter diffraction (EBSD) technique in the early 2000s. Raman spectroscopy was concluded to be most effective when applied to examining the degree of damage, as well as identifying phases and misorientation in zircon. Full article

Lunar meteorites are the fragments of rocks that fell on Earth because of the impacts of asteroids on the Moon. Such rocks preserve information about the composition, evolutionary process, and shock history of the lunar surface. NWA 13120 is a recently discovered lunar breccia meteorite having features of strong shock, which is composed of lithic and mineral clasts in a matrix of very fine-grained (<10 μm) and recrystallized olivine-plagioclase with a poikilitic-like texture. As the most abundant lithic clasts, the crystalline impact melt (CIM) clasts can be divided into four types according to their texture and mineral composition: (1) anorthosites or troctolitic anorthosite with a poikilitic-like texture, but the mineral content is different from that of the matrix; (2) anorthosites containing basaltic fragments and rich in vesicles; (3) troctolitic anorthosite containing metamorphic olivine mineral fragments; (4) troctolitic anorthosite containing troctolite fragments. Based on the petrology and mineralogy, NWA 13120 is a lunar meteorite that was derived from the ferrous anorthosite suite (FANs) of the lunar highlands, while its texture suggests it is a crystalline impact melt breccia. In addition, we infer that the parent rock of NWA 13120 is a lunar regolith breccia enriched in glass fragments. During the shock process, at pressures of more than 20 GPa, all plagioclase fragments were transformed into maskelynites, and olivine fragments occurred metamorphism. The post-shock temperature led to the partial melting of the basaltic fragments. Subsequently, all glass with diverse components in the parent rock were devitrified and recrystallized, forming the common olivine-plagioclase poikilitic-like texture and different CIM clasts. Meanwhile, the devitrification of maskelynite formed the accumulation of a large number of plagioclase microcrystals. Therefore, NWA 13120 is a meteorite of great significance for understanding the local shock metamorphism of lunar rocks on the lunar surface. Full article