Lonar Impact Crater, India: the Best-Preserved Terrestrial Hypervelocity Impact Crater in a Basaltic Terrain as a Potential Global Geopark

Lonar Impact Crater is a simple meteorite impact crater carved out on the ~ 65 Ma old Deccan tholeiitic flood basalts. The crater, though scoured in a basaltic terrain, is still preserved in its most pristine form, with a central crater lake. The geomorphology, geochemistry, geochronology, hydrology, geophysical parameters, and structural aspects of Lonar Crater have been explored in detail, but still continue to contribute valid scientific insights into the geology of terrestrial impact craters. Lonar serves as a potential analog site for studying impact cratering on planetary surfaces with basaltic terrains such as the Moon and Mars. Besides being a highly recognizable impact crater in India, the Lonar crater and its hinterland stand out with its archeological relevance and spiritual influence among the people. The numerous temples in and around the crater premises uphold the cultural significance of the region. The crater and adjacent areas are rich in flora and fauna representing a diverse ecosystem in the vastness of the arid Deccan Flood Basalts. Hence, the astrobleme and its surrounding is declared a Ramsar site and is also a protected wildlife sanctuary. The Indian Government has also declared the crater a National Geological Monument as well as an archaeological monument. Furthermore, the astrobleme is a unique site with socio-cultural and economic significance. With these plethoras of importance, combined with the geological and socio-cultural aspects in its hinterland, together with the most acclaimed UNESCO world heritage centers Ajantha and Ellora caves in the neighborhood, it stands as the right candidate for a UNESCO Global Geopark. However, the crater and its ecosystem are not preserved well enough, and the uniqueness of the crater is diminishing. But after selection as a Ramsar site, the area shows increased vegetation growth. The SWOT analysis conducted in this study accounts for Lonar Crater and its adjoining areas as a potential global geopark. Thus, through this study, we try to propagate the vivid and myriad importance of the Lonar crater and the necessity of protecting this geological monument from both anthropogenic and natural processes and to appraise the necessity for nominating this area as a UNESCO Global Geopark.

Retrieving magma composition from TIR spectra: implications for terrestrial planets investigations

Emissivity and reflectance spectra have been investigated on two series of silicate glasses, having compositions belonging to alkaline and subalkaline series, covering the most common terrestrial igneous rocks. Glasses were synthesized starting from natural end-members outcropping at Vulcano Island (Aeolian Islands, Italy) and on Snake River Plain (USA). Results show that the shift of the spectra, by taking Christiansen feature (CF) as a reference point, is correlated with SiO₂ content, the SCFM factor and/or the degree of polymerization state via the NBO/T and temperature. The more evolved is the composition, the more polymerized the structure, the shorter the wavelength at which CF is observable. CF shift is also dependent on temperature. The shape of the spectra discriminates alkaline character, and it is related to the evolution of Qn structural units. Vulcano alkaline series show larger amount of Q₄ and Q₃ species even for mafic samples compared to the subalkaline Snake River Plain series. Our results provide new and robust insights for the geochemical characterization of volcanic rocks by remote sensing, with the outlook to infer origin of magmas both on Earth as well as on terrestrial planets or rocky bodies, from emissivity and reflectance spectra.

Chondrite Shock Metamorphism History Assessed by Non-Destructive Analyses on Ca-Phosphates and Feldspars in the Cangas de Onís Regolith Breccia

The Cangas de Onís regolith breccia is an H5-H6 ordinary chondrite that fell to Earth in 1866. It is constituted by 60% H6-H5 clasts within an H5 clastic matrix. All clasts are affected by intense fissuration, with an intricate pattern filled by kamacite and troilite, shock metamorphism of plagioclase into maskelynite. The chondrite is composed of low-Ca pyroxene, olivine and plagioclase as the main silicate phases, with two types of phosphates, taenite-kamacite blebs and troilite. The specimen was studied by micro-Raman spectroscopy, Fourier-transform infrared spectrophotometry (FTIR), spectral cathodoluminescence and computer tomography. The ease with which the specimens can be prepared for analysis using these techniques, and the speed with which relevant information can be obtained, make them excellent tools for the study of non-replaceable materials. Moreover, the Raman and FTIR results offer enough resolution to reveal heterogeneities in the shocked metamorphism throughout the specimen. The obtained results showed that the extent of the metamorphic conditions within the studied sample is heterogeneous, which leads us to believe that the last accretionary event that took place in this regolithic breccia was not significant enough to allow for overall homogenization.