Neeraj Srivastava | Searcharxiv

arXiv2026

Morphological and mineralogical characterization of the Freundlich-Sharonov Basin: Implications for the lunar farside magmatism

Volcanism on the Moon is highly asymmetric, with the nearside having extensive mare emplacements and the farside exhibiting only sparse, localized volcanism. The Freundlich-Sharonov Basin (FS Basin), a preNectarian/Nectarian impact basin located on the central farside of the Moon (18.35N, 175.2E), hosts a limited volume of spatially restricted and isolated volcanic patches, which provide an ideal geological setting to investigate controls on the lunar magmatism in a thick, KREEP poor farside crust. In this study, detailed geological characterization of the FS Basin is provided for the first time, incorporating insights from morphological, chronological, and compositional analyses using high resolution datasets from missions such as Chandrayaan1 (Moon Mineralogy Mapper), Kaguya, and Lunar Reconnaissance Orbiter. The results of this study reveal a previously undetected ~192 km diameter inner depression ring, along with spatially aligned subsurface magmatic intrusions, and exposures of PAN and orthopyroxenes along the basin rings. Compositional analyses indicate that the FS Basin experienced at least two volcanic eruptions dominated by exceptionally high-alumina basalts (~16 to 24 wt% Al2O3) around ~3.4 Ga and ~2.1 Ga. This is the highest reported alumina content in the lunar maria, also expanding the period of known high alumina volcanism on the Moon to the late phase. We propose that the limited extent of volcanic eruptions in the FS Basin is a result of the combined effects of composition-dependent magma buoyancy, reduced magma production, and impact modified crustal structures determining the magma extrusion sites.

astro-ph.EP↗

arXiv2023

Chandrayaan-3 Alternate Landing Site: Pre-Landing Characterisation

India's third Moon mission Chandrayaan 3 will deploy a lander and a rover at a high latitude location of the Moon enabling us to carry out first ever in-situ science investigations of such a pristine location that will potentially improve our understanding on primary crust formation and subsequent modification processes. The primary landing site (PLS), is situated at 69.367621 degS, 32.348126 degE. As a contingency, an alternate landing site (ALS) was also selected at nearly the same latitude but nearly 450 km west to PLS. In this work, a detailed study of the geomorphology, composition, and temperature characteristics of ALS has been carried out using the best-ever high resolution Chandrayaan 2 OHRC DEMs and Ortho images, datasets obtained from Chandrayaan 1 and on-going Lunar Reconnaissance Orbiter. For understanding the thermophysical behaviour, we used a well-established thermophysical model. We found that the Chandrayaan 3 ALS is characterised by a smooth topography with an elevated central part. The ALS is a scientifically interesting site with a high possibility of sampling ejecta materials from Tycho and Moretus. Based on the spectral and elemental analysis of the site, Fe is found to be near approx. 4.8 wt.%, with Mg approx. 5 wt.%, and Ca approx. 11 wt.%. Compositionally, ALS is similar to PLS with a highland soil composition. Spatial and diurnal variability of around 40 K and 175 K has been observed in the surface temperatures at ALS. Although belonging to similar location like PLS, ALS showed reduced daytime temperatures and enhanced night-time temperatures compared to PLS, indicating a terrain of distinctive thermophysical characteristics. Like PLS, ALS is also seems to be an interesting site for science investigations and Chandrayaan 3 is expected to provide new insights into the understanding of lunar science even if it happens to land in the alternate landing site.

astro-ph.EP↗