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Lunar grabens are the largest tensional linear structures on the Moon. In this paper, 17 grabens were selected to investigate the dips and displacement–length ratios (γ) of graben-bounding faults. Several topographic profiles were generated from selected grabens to measure their rim elevation, width and depth through SLDEM2015 (+LOLA) data. The differences in rim elevation (∆h) and width (∆W) between two topographic profiles on each graben were calculated, yielding 146 sets of data. We plotted ∆h vs. ∆W for each and calculated the dip angle (α) of graben-bounding faults. A dip of 39.9° was obtained using the standard linear regression method. In order to improve accuracy, large error data were removed based on error analysis. The results, 49.4° and 52.5°, were derived by the standard linear regression and average methods, respectively. Based on the depth and length of grabens, the γ value of the graben-bounding normal fault is also studied in this paper. The γ value is 3.6 × 10−3 for lunar normal faults according to the study of grabens and the Rupes Recta normal fault. After obtaining the values of α and γ, the increase in lunar radius indicated by the formation of grabens was estimated. We suggest that the lunar radius has increased by approximately 130 m after the formation of grabens. This study could aid in the understanding of normal fault growth and provide important constraints on the thermal evolution of the Moon. [ABSTRACT FROM AUTHOR]

The specific duration between the impact event and subsequent volcanic flows is highly variable based on previous works. The method of crater size-frequency distribution (CSFD) has been previously used to date the basalt in Orientale Basin, which yielded inconsistent resultant Absolute Model Age (AMA) ranges. The inconsistency may be attributed to the choice of counting area and identified superposed craters. In this study, we integrated the Chang'E-2 (CE-2) imaging data (7 m/pix) and the IIM and 20 m CE-2 DTMS data, re-divided Mare Orientale, and re-estimated the age of the basalts there. The ages revealed that (1) the central basalts had multiphase eruptions, beginning at 3.77 Ga (30 My after the impact event) with the longest duration of 1.51 Gy; (2) the edge basalts have a similar features as the central basalts, beginning at 3.75–3.50 Ga (50–300 My after the impact) with the longest duration of 0.67 Gy. Compared with the basalts along the basinal margin, the central basalts have higher Ti but lower Mg# contents, consistent with the basaltic magma fractionation trend. Spatial distribution characteristics indicate that the basalt eruption occurred in the impact direction upstream and in the center, but almost absent in the impact direction downstream. Accordingly, we speculate that the longevity of the lunar mare basaltic volcanism was affected by gravity changes, material balance, and other post-impact processes. [ABSTRACT FROM AUTHOR]

Impact basins are primary geological structures on the Moon, and play key roles in revealing the lunar history. Due to the different identification standards currently used, the basin identification results are highly inconsistent. Except for the major basins (e.g., Orientale, Schrödinger, Imbrium, Crisium, Apollo, and Nectaris Basin), detailed sub-formation interpretations for most other basins are lacking, which hampers the construction of a complete (global) geological interpretation for the lunar impact basins. Based on multisource remote sensing data and previous works, we established a basin identification standard, and a new global lunar basin catalog containing 81 basins. According to the ring diameter ratios, the purest anorthosite (PAN) distribution, and basin radial textures, we divided the basin sub-formations into the central-peak, peak-ring, basin-floor, basin-wall, basin-rim, and basin-ejecta formations. We interpreted the ejecta formation and other basin sub-formations by combining the Focal Flow data with LROC WAC images, topographic data, gravity anomalies, and spectral data. Our new lunar geologic map shows more precise distribution of basin formations, covering nearly 70% of the lunar surface. Moreover, we obtained the origin of basin rings using basin sub-formations map. Additionally, the basin sub-formation map can contribute to the basin impact conditions, such as the discovered ring (concentric with the outermost ring) provides evidence for three impacts in the Mare Moscoviense, and the SPA sub-formation distribution indicates the impact direction of SPA is SE-NW. Furthermore, the sub-formation distribution can facilitate the geological characteristics and evolution study of the lunar exploration sites. • Impact basin identifying standard and new global lunar basin catalog established. • Basin sub-formations divided based on ring ratio, PAN distribution, and basin radial textures. • Focal Flow data first used to interpret sub-formation, improving map resolution. • A more accurate distribution map of lunar basin formations is produced. [ABSTRACT FROM AUTHOR]