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Silicic lithologies on planetary surfaces indicate magmatic evolutionary processes in their interiors. The Wolf crater complex within Mare Nubium on the Moon is one such silicic construct associated with a high thorium anomaly. This study integrates morphological, compositional, chronological and gravity anomaly analyses of high‐resolution data from various lunar missions to establish this construct as a silicic volcanic caldera. Lobate flows with steeply sloping fronts indicate that the crater rims comprise high‐viscosity silicic lavas, while the structurally controlled inner crater walls suggest caldera collapse triggered by magma depletion. In the crater rims, low Christiansen Feature position values reaffirm the presence of silicic lithologies, consistent with the low gravity anomaly signature beneath the complex, while spectroscopic data reveal low mafic mineral abundances and negligible hydration features. Chronological analyses yield silicic volcanism ages coeval with surrounding mare basalts (3.8–3.6 Ga), while intra‐caldera basalts have 2.36–2.02 Ga ages, indicating prolonged magmatism in this region. Melting of suitable crustal protoliths like alkali gabbronorite/monzogabbro/troctolite by basaltic underplating is inferred to have generated silicic magmas that formed the Wolf volcanic complex, instead of basaltic magma fractionation or silicate‐liquid immiscibility processes. Large impacts during the Late Heavy Bombardment may have enhanced partial melting of the mantle and created crustal fractures that facilitated the ascent of viscous silicic melts through the lunar crust. Contemporaneous existence of suitable protoliths and adequate crustal pathways for magma ascent may have controlled silicic volcanism on the Moon, and can explain the sporadic occurrence and overlapping ages of the lunar silicic constructs. Plain Language Summary: Understanding how evolved silica‐rich rocks formed on the Moon can shed light on the magmatic differentiation and thermal evolution of the lunar mantle. Here, we study one such silicic region called the Wolf crater complex on the lunar nearside using compositional and morphological evidence from high‐resolution images and remotely sensed data. Spectroscopic and gravity studies confirm that the rocks have a silicic composition but with negligible water content. The complex is characterized as a silicic volcanic crater/caldera that was later filled with basalt. Formation of the volcano and its collapse to form the caldera were controlled by pre‐existing structures. Ages calculated by crater‐counting methods suggest that magmatic activity persisted in this region for ∼2 billion years. These apparently dry silicic melts could not have been derived by fractionation or unmixing of basaltic magmas. Instead, large impacts in the region may have thinned the crust, enhancing partial melting of the underlying mantle and facilitating basaltic underplating of the crust. Melting of appropriate protoliths (alkali gabbronorite/monzogabbro/troctolite), where present in the underplated crust, may generate viscous silicic melts whose ascent is then facilitated by impact‐generated fractures. This model explains why lunar silicic constructs are rare and have ages broadly synchronous with the Late Heavy Bombardment. Key Points: The Wolf crater complex is a volcanic caldera where silicic volcanism occurred between ∼3.6–3.7 Ga, followed by mafic volcanism till ∼2.02 GaStructural trends imposed by regional pre‐existing fracture systems facilitated both melt eruption and caldera collapseNear anhydrous melting of appropriate crustal protoliths caused by basaltic underplating generated the silicic melts [ABSTRACT FROM AUTHOR]

The presence of polygonal-shaped craters, i.e., craters with complete or incomplete polygonal rims along with circular or elliptical outlines, on the surface of celestial bodies has been known for nearly a century. However, many investigations on their distribution and formation have not been carried out, until recently. Scientists have proposed that the polygonal shapes of the crater rims owe their origin to the pre-existing structurally weak planes like faults/fractures in the area adjacent to the impact. The present study area is the southern part of Margaritifer Terra, Mars; a mid-Noachian terrain, which has craters of different morphologies, including the polygonal impact craters (PICs). The study focuses on the reason for the development of PICs by identification and mapping of a population of 50 selected polygonal craters along with morphotectonic features namely grabens, wrinkle ridges, and lobate scarps. The analysis of orientations of the straight segments of polygonal crater rims shows marked resemblance with orientations of these morphotectonic features conforming to their control on the rim geometries. Research highlights: Structural mapping of the southern Margaritifer Terra region, Mars. Generating rose diagrams and line graphs for the orientation of the straight edges of polygonal craters and the morphotectonic features within the southern Margaritifer Terra region. Conducting statistical F-test to find out the bearing of weak planes on the formation of PICs. Finding out the presence of buried weak planes by comparing the rose diagrams and spike graphs. [ABSTRACT FROM AUTHOR]

High-resolution spectral and spatial data analyses of crater Theophilus revealed the presence of hydroxyl-bearing exposures of possible magmatic origin on its central peak in association with olivine-, spinel- and crystalline plagioclase-bearing lithologies. Hydroxyl-bearing lithologies at Theophilus central peak are characterized primarily by a prominent absorption feature near 2800 nm, the strength of which varies from ∼2% to 6% in some localized zones within the central peak. The strong and sharp 2800-nm hydroxyl feature having localized occurrences on the central peak of crater Theophilus is inconsistent with a surficial origin. We suggest that the observed hydration at Theophilus central peak could possibly be associated with a sub-crustal magmatic source that was subsequently tapped and exposed by Theophilus impact event. [ABSTRACT FROM AUTHOR]

On the Moon, impact craters and basins expose a wide range of crustal and mantle rocks that provide excellent opportunity for sampling them, understanding their origins and reconstructing spatial and temporal evolution of lunar interior. The previous studies detected olivine-bearing mantle rocks in and around large impact craters and basins. The Japanese SLIM mission landed on the ejecta of a ∼ 280-m-diameter Shioli crater that was emplaced on the ejecta blanket of ∼ 103-km-diameter Theophilus crater, for characterizing potential mantle-derived olivine in the Shioli crater ejecta boulders. To test this hypothesis, we studied the geological setting of Shioli crater, host Theophilus crater and Nectaris multi-ring basin using the orbiter data from Chandrayaan-1 and 2, Lunar Reconnaissance Orbiter, and Kaguya missions and the earth-based Arecibo radar observation. The asymmetrically distributed secondary craters and impact melt ponds around Theophilus crater suggests that a northeast-directed oblique impact produced this crater. Composition of Theophilus crater and surrounding region indicates that the crater excavated a heterogeneous target composed of a thin layer of high-Al olivine basalt (Mare Nectaris) underlain by anorthositic highland rocks possibly intruded by Mg-suite plutons; layers of Cyrillus crater ejecta blanket and Nectaris basin materials (both ejecta and impact melt sheets) were also present beneath the mare basalt flows. Hence, the Theophilus ejecta blanket is a mixture of all these materials. Our dating of Theophilus crater suggests that it is a ∼ 2 Ga Eratosthenian crater. Shioli is a fresh simple crater that was formed at ∼ 1 Ma on the uprange ejecta blanket of Theophilus, where the Arecibo radar data indicated the presence of abundant buried Theophilus ejecta boulders. An ESE-directed hypervelocity oblique impact event produced the elongated Shioli crater and its asymmetrically distributed bright ejecta. Shioli is a primary impact crater indicating the role of impact spallation processes associated with this hyper-velocity impact in producing thousands of ejecta (or spall) boulders around Shioli crater, displaying their asymmetric dispersal pattern and spatial variation of boulder sizes and shapes. The larger and elongated boulders are concentrated near the crater rim, while their size and axial ratio gradually decreases outward from the crater rim. The SLIM mission landed on a thin downrange ejecta of Shioli crater, where fewer large-size boulders are present. Our compositional study suggests that the Shioli ejecta boulders are composed of olivine basalt (Mare Nectaris) mixed with highland anorthositic fragments, including the reworked Cyrillus ejecta and Nectaris basin materials. The Shioli ejecta boulders were produced by complex impact fragmentation of already existing, buried Theophilus ejecta boulders. The regional crustal structure of Nectaris basin and its petrological composition suggest that both Nectaris basin and Theophilus crater did not excavate the lunar mantle. Therefore, the Shioli ejecta boulders are of crustal origin, including the olivine minerals present in them. Our results have important implications for the origin of olivine in the Shioli crater boulders being investigated by the SLIM mission. • A NE-directed oblique impact produced Theophilus crater, asymmetric distribution of secondary craters and impact melt ponds • Theophilus excavated a thin layer of high-Al olivine mare basalt underlain by Cyrillus ejecta and highland anorthositic rocks • An east-southeast directed oblique impact produced Shioli crater and its asymmetrically distributed ejecta and spall boulders • A hypervelocity impact (16 km/s) is responsible for the observed size and shape variation in the Shioli crater spall boulders • The Shioli boulders are mixtures of olivine basalt and highland materials, produced from Theophilus ejecta boulders [ABSTRACT FROM AUTHOR]

In this work, we performed a detailed characterization, of the inter-crater region around the Chandrayaan-3 landing site (LS) using remote sensing data sets obtained from Chandrayaan-2 and other missions. The regolith material at LS is mainly derived from the large craters such as Manzinus, Schomberger craters, etc. and the excavated ejecta of South Pole Aitkin (SPA) basin. The regional slope of the inter-crater plains is found to be <5°, and the local slope around LS to be <3° with minor variations in surrounding topographic relief, which affirms that the LS region is situated in topographic plains. The absolute model age of the LS region was found to be ∼ 3.94 − 0.04 + 0.03 Ga, indicating Nectarian age, and it is consistent with the published geological maps. Moreover, high-resolution images, rock abundance, night-time regolith anomaly temperature, and radar data suggest that the LS region is smooth at centimeter- to decimetre-scale and is devoid of wavelength-scale scatterers such as ground cracks, exposed surface rocks and meter sized boulders. Additionally, the estimated daytime temperature range, hydration abundance, and Water Equivalent Hydrogen near the LS were found to be on average < 290 K, <100 ppm, and ∼ 500 ppm, respectively. The regional crustal structure below the lunar South polar region, covering the LS, shows two prominent sub crustal features which may be related to the lobate scarps, including the one near to LS. The results obtained in this work could set up additional constraints to the observations obtained by instruments on board the Chandrayaan-3 mission. This work also acts as a pre-investment study from the point of view of future sample return missions of ISRO, in which one of the potential landing site could be the inter-crater plain surrounding the Chandrayaan-3 landing site. • Surface temperature and hydration at the Chandrayaan 3 landing site were estimated using IIRS data. • The regolith materials present at the Chandrayaan-3 landing site were contributed by surrounding large craters. • Using GRAIL data, we interpreted the interior structures present beneath the lunar south polar region. [ABSTRACT FROM AUTHOR]

Imaging Infrared Spectrometer (IIRS) on-board Chandrayaan-2 is designed to measure lunar reflected and emitted solar radiation in 0.8-5.0 μm spectral range. Its high spatial resolution (~80 m) and extended spectral range is most suitable to completely characterize lunar hydration (2.8-3.5 μm region) attributed to the presence of OH and/or H2O. Here we present initial results from IIRS reflectance data analysed to unambiguously detect and quantify lunar 3 μm absorption feature. After pre-processing and data-reduction, a physics based thermal correction analysis of IIRS reflectance spectra has been done using co-located temperature measurements. Hydration absorption was observed at all latitudes and surface types with varying degrees for all pixels in the study area and its absorption depth shows distinct variability associated with mineralogy, surface temperature and latitude. [ABSTRACT FROM AUTHOR]

The mineralogy and morphology of class-1 type lunar floor-fractured crater (FFC) (i.e., the lunar FFCs having central peak complexes, radial and/or concentric fractures, extended wall terraces and crescent-shaped mare patches over the crater floor) Atlas has been investigated thoroughly in this study using high-resolution data from recent lunar missions. Spectral data from the Moon Mineralogy Mapper (M3) interestingly reveal a mafic-rich central peak complex (CPC) for crater Atlas unlike other class-1 FFCs. The mafic–rich CPC suggests the possible tapping of a mafic pluton emplaced at a shallow subsurface level. The crater floor hosts two localized late-stage, Vulcanian-type pyroclastic deposits exhibiting varied TiO 2 concentrations. We further report two categories of hydration features in crater Atlas: (1) Endogenic - associated with nominally anhydrous minerals (NAMs), namely, olivine, pyroxenes and Mg-spinel, in the CPC and on the southern crater wall, and with the pyroclastic deposits; (2) Exogenic - related to solar wind implantation in matured soils in the crater floor. In the present study, a detailed quantitative analysis of the hydration features has been presented. The hydration features associated with NAMs imply a hydrous nature of the mantle-sourced magma that formed the mafic pluton. Overall, the varied water contents associated with the NAMs and the two pyroclastic patches indicate heterogeneity in the hydrous enrichment of the lunar mantle underneath the studied site. The high-resolution morphological study unravels a partially uplifted crater floor, and several features like radial, elongated and concentric fractures, which suggest that the floor had suffered numerous brittle and ductile deformations. The radial and concentric fracture systems have different dimensions, indicating spatial variation in stresses suffered when the floor uplift. The localized pyroclastic deposits and the warped crater floor suggest multiple events of late stage magmatic activity. • We report mineralogical diversity within the crater Atlas based on Chandrayaan-1 Moon Mineralogy Mapper (M3) observations. • Mafic mineralogies of the central peak complex signify a mid to lower crustal plutonic source. • Endogenic hydration feature has been detected and quantified and possibly suggests a hydrated lunar interior. • An evolutionary model showing the stages of development of crater Atlas is presented. [ABSTRACT FROM AUTHOR]

Hyperspectral imagery (HSI) in the visible to near-infrared wavelength region has a high potential for deciphering mineral compositions of terrestrial and planetary surfaces. Thus, ISRO's Imaging Infrared Spectrometer (IIRS) sensor onboard Chandrayaan-2 (Ch-2) orbiter provides an opportunity to utilise the hyperspectral observations to characterise the lunar surface minerals and composition significantly. Hence, a sensitivity study of hyperspectral observations of the IIRS sensor was carried out for the detection and mapping of various lunar minerals using spectral unmixing analysis. A common region within the hyperspectral image obtained from Chandrayaan-1's (Ch-1) Moon Mineralogy Mapper (M3) sensor and Ch-2 IIRS sensor has been identified in the South-East of the Taurus-Littrow valley nearby Gardner crater for comparison and validation purposes. Ch-2 IIRS is an advanced hyperspectral imaging spectrometer capable of collecting spectra over a wider spectral range (800 ​nm ​− ​5000 ​nm) with high spatial (~80 m) and spectral resolution (20 n m ​− ​25 ​n m). To examine spectral unmixing analysis, an electromagnetic range (800 ​nm ​− ​2500 ​nm) in the near-infrared region was chosen for the Ch-2 IIRS sensor. An L 1 ​− ​ norm based denoising algorithm is used for mixed noise removal from both the IIRS and M3 reflectance datasets. Endmember extraction and fractional abundance estimation are carried out using the N-Findr algorithm and the fully-constrained least square method, respectively. Our results reveal different minerals such as high-calcium pyroxene (Clinopyroxene), low-calcium pyroxene (Orthopyroxene), and regolith surface (matured and younger). The results obtained from the IIRS and M3 observations are in strong agreement. Hence, the hyperspectral observations made by the IIRS sensor are extremely effective for describing the mineral and chemical compositions of the lunar surface. • Spectral unmixing analysis is executed to determine lunar surface mineralogy and their abundance using Hyperspectral data. • For comparative analysis, co-located datasets from Chandrayaan-2 (Ch-2) IIRS and Chandrayaan-1(Ch-1) M3 are investigated. • An L1-norm-based denoising algorithm is introduced to significantly improve the data quality by removing the complex noise. • The methodology can be automated to develop the lunar mineralogical and chemical map in a time-efficient and systematic way. [ABSTRACT FROM AUTHOR]

Tycho is a young impact crater of Copernican age (∼ 110 Ma) in the southern highlands of the Moon. The crater has a well-developed central peak with an altitude of ∼ 2 km. Central peaks of large lunar craters are ideal to study the deep-seated crustal material. In this study we report the results of an integrated morphological and compositional analysis for the central peak of the Tycho crater by using high-resolution data from Terrain Mapping Camera (TMC) and Moon Mineralogy Mapper (M3) on-board Chandrayaan- 1 along with data from Narrow Angle Camera (NAC) of Lunar Reconnaissance Orbiter. Our analysis shows various morphological features associated with volcanism in the form of volcanic vents, domes, clasts, impact melt lava ponds showing distinct cooling cracks, and flow patterns on and around this central peak. Compositionally, M3 data suggest that the central peak is highly heterogeneous and dominated by high-Ca pyroxene-rich rocks. The base of the central peak is anorthositic in nature. These new morphological and mineralogical evidences suggest that the central peak of the Tycho crater has diverse morphology and mineralogical variability, suggesting multiphase modifications subsequent to the crater formation. The presence of diverse mafic lithologies on the central peak situated, in a predominantly anorthositic geological setting, suggests exposure of the subsurface pluton during the impact and thus provides insight into the composition of the lunar inner crust. [ABSTRACT FROM AUTHOR]