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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]

In the present study, the principal objective is to investigate the role of multiple tuned mass damper (MTMD) to reduce aerodynamic effect of wind force on "V" plan-shaped high-rise buildings with the various internal limb angle. Distinct cases have been made by considering the angle between the limbs is 90° which is gradually increased from 90° to 150° with 15° regular interval and decreased from 90° to 40° with 10° regular interval maintaining same plan area and limb width subjected from 0° to 180° wind incidence angle with 30° regular interval. Computational fluid dynamics (CFD) is adopted to determine the aerodynamic coefficients by numerical simulation. A polynomial expression has been proposed to compute force, moment, and torsional coefficient along X, Y, and Z direction from the entire result for avoiding rigorous calculation. Dynamic wind time history in along and crosswind is obtained using maximum force coefficient. The dynamic response analysis such as peak displacement, acceleration is obtained for selected models with MTMD and effectiveness of MTMD is computed. Finally, the influence of MTMD and internal angle variation on the wind-induced response of "V" plan-shaped buildings have been observed to determine suitability of internal angle variation based on the numerical result. [ABSTRACT FROM AUTHOR]

The study is on the variation of pressure in different faces of rectangular plan-shaped tall buildings with interference conditions due to the presence of another building with the same shape and dimension connected through a multipurpose bridge. The analysis is done on computational fluid dynamics (namely ANSYS CFX) for 0° to 90° wind incidence angle (WIA). The buildings are spaced 60 m from each other. Different cases have been taken and analyzed based on the different positions of the bridge (i.e., 0.33H, 0.5H, and 0.67H) and compared with the isolated case (i.e., buildings without the bridge). A comparison study has been done in the form of interference factor (IF), so we can clearly understand the effect of the bridge at different heights of the building and isolated conditions on rectangular plan-shaped buildings. The study shows that when the bridge is at 0.5H and 0.33H, the force coefficient along X and Y produces similar results to an isolated condition for WIA of 60° and 30°, respectively. [ABSTRACT FROM AUTHOR]

Summary: In this study, a "V" plan‐shaped building with single tuned mass damper (STMD) and multiple tuned mass damper (MTMD) is analyzed in alongwind and crosswind direction considering different mass ratios and tunning ratios. The force coefficient of the "V" plan‐shaped tall building is determined by computational fluid dynamics (CFD) method to obtain the time history function of dynamic wind force. An optimum ratio has been adopted to compare the effectiveness of MTMD over STMD installed in the V‐shape building model. Power spectral density of displacement, acceleration, base shear, base moment, and torsional moment due to dynamic wind time history are determined to investigate the vibration control of MTMDs and STMDs. Finally, the optimal mass ratio of the maximum reduction in response and control effectiveness in percentage has been determined for each parameter. The present study indicates that MTMDs are more effective to mitigate wind‐induced vibration than STMDs. [ABSTRACT FROM AUTHOR]

The Hansteen‐Billy region of the Moon lying toward the southwest edge of Oceanus Procellarum is characterized by emplacement of three different aged basaltic units viz. INm, Im, and Em. The present study primarily utilizes high‐resolution Chandrayaan‐I, Moon Mineralogy Mapper (M3) data clipped at ~2.5 μm for mineral analysis of these units. The spectra of all the three regions show two prominent absorption bands. Spectral analysis characterizes the earliest INm basalts as low‐Ca pyroxenes with large band area ratios (BAR) and nearly similar B‐I and B‐II strength. The Em and Im basalts are Ca and high‐Ca pyroxenes, respectively, with relatively less BAR values and more B‐II/B‐I strength. The relative content of their spectra after olivine correction appears to be dominated by pyroxene. The obtained results have been used for estimation of the compositional characteristics of pyroxenes from laboratory‐based calibration equations. The pyroxene composition for INm basalts indicates their pigeonitic affinity, whereas the Im and Em basalts is close to augite. The estimated temperature of crystallization suggests that basalts in this region evolved at higher temperature and are preserved in a metastable condition due to quick cooling. Furthermore, the area is characterized by increase in concentration of both the Fe and Ti with age as assessed from Clementine mineral map. The obtained results have been discussed in relation with source of the magma. [ABSTRACT FROM AUTHOR]

Here, we present the detailed chemical and spectral characteristics of gypsum‐phyllosilicate association of Karai Shale Formation in Tiruchirapalli region of the Cauvery Basin in South India. The Karai Shale Formation comprises Odiyam sandy clay and gypsiferous clay, well exposed in Karai village of Tiruchirapalli area, Tamil Nadu in South India. Gypsum is fibrous to crystalline and translucent/transparent type with fluid inclusions preserved in it. Along some cleavage planes, alteration features have been observed. Visible and near infrared (VNIR), Raman, and Fourier transform infrared techniques were used to obtain the excitation/vibration bands of mineral phases. VNIR spectroscopic analysis of the gypsum samples has shown absorption features at 560, 650, 900, 1,000, 1,200, 1,445, 1,750, 1,900, 2,200, and 2,280 nm in the electrical and vibrational range of electromagnetic radiation. VNIR results of phyllosilicate samples have shown absorption features at 1,400, 1,900, and 2,200 nm. Further, we have identified the prominent Raman bands at 417.11, 496.06, 619.85, 673.46, 1,006.75, 1,009.75, ∼1,137.44, ∼3,403, and 3,494.38 cm−1 for gypsum due to sulphate and hydroxyl ion vibrations. We propose that gypsum veins in Karai may have precipitated in the fractures formed due to pressure/forces generated by crystal growth. The combined results of chemical and spectral studies have shown that these techniques have significant potential to identify the pure/mineral associates/similar chemical compositions elsewhere. Our results definitely provide the database from a range of spectroscopic techniques to better identify similar minerals and/or mineral‐associations in an extraterrestrial scenario. This study has significant implications in understanding various geological processes such as fluid‐rock interactions and alteration processes involving water on the planets such as Mars. [ABSTRACT FROM AUTHOR]

Green authigenic mica, i.e., celadonite, is commonly associated with submarine alteration of basic igneous rock. However, very few studies have reported the formation of celadonite under nonmarine conditions. An integrated study involving field investigation, petrography, mineralogy, and mineral chemistry highlighted the origin of celadonite in two clay-rich horizons (green boles) of the Late Cretaceous Deccan volcanic province. Within the Salher green bole, the celadonite occurred as the dissolution and alteration of plagioclase, volcanic glass, and pore-filling cement. In the case of the Pune green bole, the celadonite was formed by the alteration of plagioclase, pyroxene, and precipitation as film within intergranular pores, along with zeolite. The celadonite in the Salher green bole exhibited slightly lower K2O and Fe2O3 and higher Al2O3 than in the Pune. The mineral chemistry of the former showed a composition closer to ferro-aluminoceladonite. Although the mineral chemistry of celadonite overlaps with glauconite, the distinct 10 Å and 15 Å reflections in XRD, euhedral lath and honeycomb morphology under SEM, and characteristic absorption bands in VNIR spectroscopy (0.4–2.5 µm) and FTIR spectroscopy (400–4000 cm−1) identified celadonite and Fe-smectite within green boles. The green boles were formed either by the alteration of a volcaniclastic deposit in local pools of water or by the in situ alteration of the fragmentary flow top. The present study is significant due to the occurrence of celadonite in a nonmarine environment, as it otherwise forms under submarine conditions. [ABSTRACT FROM AUTHOR]

We have conducted spectral and spatial analysis of the Compton-Belkovich Thorium Anomaly (61.1°N, 99.5°E) region on the far side of the Moon based on high-resolution data from recent lunar missions. Chandrayaan-1 Moon Mineralogy Mapper data of Compton-Belkovich volcanic complex (CBVC) reveal the existence of a strong doublet feature near 2800 nm throughout the volcanic construct, which could be attributed to the presence of water and/or hydroxyl in the studied site. Very high resolution Lunar Reconnaissance Orbiter Camera-Narrow Angle Camera mosaic of the study area shows that the strongest of the hydration features within the CBVC is primarily related with either sunlit inner flanks of small-sized fresh craters or fresh escarpments associated with the central collapse structure. Moreover, Mini-RF Synthetic Aperture Radar data from Lunar Reconnaissance Orbiter mission suggests the presence of a thick pyroclastic deposit in the volcanic complex. Our study indicates that the enhanced hydration at CBVC could possibly have originated from the episodic events of eruption and effusion involving silicic magma, which could probably be responsible for the tapping of a zoned magma body with a water-rich cap. Morphology of CBVC also confirms the presence of episodic effusive and eruptive events that probably had led to the formation of elevated topography, central collapsed feature and late eruptive domes in the study area. [ABSTRACT FROM AUTHOR]

Abstract: Spectral analysis of Mare Serenitatis has been carried out using Chandrayaan-1 Moon Mineralogy Mapper (M3) data in order to map the compositional diversity of the basaltic units that exist in the basin. Mare Serenitatis is characterized by multiple basaltic flows of different ages indicating a prolonged volcanism subsequent to the basin formation event. Reflectance spectra of fresh craters from the Mare Serenitatis have been analyzed to study the nature and location of the spectral absorption features around 1- and 2-μm respectively, arising due to the electronic charge transition of Fe2+ in the crystal lattice of pyroxenes and/or olivine. Chandrayaan-1 M3 data have been utilized to obtain an Integrated Band Depth (IBD) mosaic of the Serenitatis basin. Based on the spectral variations observed in the IBD mosaic, 13 spectral units have been mapped in the Mare Serenitatis. In the present study, we have also derived spectral band parameters, namely, band center, band strength, band area and band area ratio from the M3 data to study the mineralogical and compositional variations amongst the basaltic units of the studied basin. On the basis of spectral band parameter analysis, the pyroxene compositions of the basaltic units have been determined, which vary from low to intermediate end of the high-Ca pyroxene and probably represent a sub-calcic to calcic augite compositional range. Detailed spectral analyses reveal little variations in the mafic mineralogy of the mare basalts in terms of pyroxene chemistry. The uniformity in pyroxene composition across the basaltic units of Mare Serenitatis, therefore, suggest a probably stable basaltic source region, which might not have experienced large-scale fractionation during the prolonged volcanism that resulted in filling of the large Serenitatis basin. [Copyright &y& Elsevier]

Abstract: We conducted spectral analysis of central region of the Mare Moscoviense area on the far side of the Moon using the Hyperspectral Imager (HySI) data from the Chandrayaan-1 mission in an effort to identify and map the major lithological units present in the area. Various spectral band parameters, namely, band curvature, band tilt and band strength have been used for lithological discrimination based on the nature of the spectral profile. These band parameters essentially measure the shape, position and strength of the absorption feature near 1000nm arising due to electronic transition of Fe2+ in crystallographic sites of major rock forming silicates. Spectral band parameters have been used for generating rock type composite image. Based on spectral studies and rock type composite image as obtained using band parameters, five major compositional units have been identified: highland basin soils, ancient mature mare, highland contaminated mare, buried unit with abundant low-Ca pyroxene (LCP), and youngest mare unit. In the present study, a multispectral approach in the form of spectral band parameters has been adopted for analysing the HySI hyperspectral data from Chandrayaan-1 mission. Present study clearly shows that the spectral band parameters obtained using selected HySI channels could efficiently be used to discriminate and delineate the major litho-units present across the central part of Mare Moscoviense and the same approach can thus be used for lithological mapping of other parts of lunar surface using HySI data. [Copyright &y& Elsevier]

The article presents a study which examines the mineral composition of lunar orbits which were mapped through the first Indian moon mission of Chandrayaan-1. The study uses two core sensors aboard Chadrayaan-1, the Hyper Spectral Imaging Camera (HySI), which operates with a spectral resolution, and the Terrain Mapping Camera (TMC). The results show the abundance of plagioclase feldspar, iron oxide, and titanium oxide in the orbits, and the variation of mineral contents in terms of elevation.

Preliminary investigations on the Infrared Spectrometer onboard Mars 2020 Perseverance rover show the presence of Fe-/Mg-smectite minerals near the first drilling site, Roubion. Laser-Induced Breakdown Spectrometer data show characteristic emission peaks for O, H and the major constituent elements of smectites, viz. Si, Fe, Mg, etc. These minerals suggest aqueous alteration of the basaltic floor of the Jezero crater. The mechanically weak nature of this basalt weathering layer holds clues to the non-retrieval of the first drill core. Water confinement capacity and high porosity-permeability make the smectite-rich rock units a good host for preserving macro- and microscopic biosignatures. [ABSTRACT FROM AUTHOR]

The article presents information on the impact of meteorite on the Moon that excavates materials from depth and its redistribution on the lunar surface. It informs that these morphological entities can be assumed as a window on the lunar surface that offer way to explore the lower crustal and upper mantle composition of the Moon. It further informs that the several graphs related to this discovery are also presented.

The Imaging InfraRed Spectrometer (IIRS) on board Chandrayaan-2 has been providing high spatial and spectral resolution observations of the lunar surface in 256 spectral bands (0.7-5 µm) since September 2019. It is primarily intended for mineral mapping and identifying hydration features on the lunar surface using reflectance spectra in the range of 0.7-3.2 µm. Here, we have used the IIRS observations in the 3-5 µm range to retrieve daytime lunar surface temperature and spectral emissivity using an optimal estimation theory-based retrieval algorithm. The surface temperature is retrieved at every pixel, while spectral emissivity is retrieved at every third pixel of the hyperspectral image. The mean uncertainty of the retrieved spectral emissivity varies from 0.04 to 0.08, while for surface temperature, it is about 3.5 K. The retrieved spectral emissivity is found to be in close agreement with the emissivity of the Apollo-16 return soil samples. [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]

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]