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.

Shaping of the Present-Day Deep Biosphere at Chicxulub by the Impact Catastrophe That Ended the Cretaceous

We report on the effect of the end-Cretaceous impact event on the present-day deep microbial biosphere at the impact site. IODP-ICDP Expedition 364 drilled into the peak ring of the Chicxulub crater, México, allowing us to investigate the microbial communities within this structure. Increased cell biomass was found in the impact suevite, which was deposited within the first few hours of the Cenozoic, demonstrating that the impact produced a new lithological horizon that caused a long-term improvement in deep subsurface colonization potential. In the biologically impoverished granitic rocks, we observed increased cell abundances at impact-induced geological interfaces, that can be attributed to the nutritionally diverse substrates and/or elevated fluid flow. 16S rRNA gene amplicon sequencing revealed taxonomically distinct microbial communities in each crater lithology. These observations show that the impact caused geological deformation that continues to shape the deep subsurface biosphere at Chicxulub in the present day.

Three-Dimensional Model of the Moon with Semantic Information of Craters Based on Chang'e Data

China’s Chang’e lunar exploration project obtains digital orthophoto image (DOM) and digital elevation model (DEM) data covering the whole Moon, which are critical to lunar research. The DOM data have three resolutions (i.e., 7, 20 and 50 m), while the DEM has two resolutions (i.e., 20 and 50 m). Analysis and research on these image data effectively help humans to understand the Moon. In addition, impact craters are considered the most basic feature of the Moon’s surface. Statistics regarding the size and distribution of impact craters are essential for lunar geology. In existing works, however, the lunar surface has been reconstructed less accurately, and there is insufficient semantic information regarding the craters. In order to build a three-dimensional (3D) model of the Moon with crater information using Chang‘e data in the Chang‘e reference frame, we propose a four-step framework. First, software is implemented to annotate the lunar impact craters from Chang’e data by complying with our existing study on an auxiliary annotation method and open-source software LabelMe. Second, auxiliary annotation software is adopted to annotate six segments in the Chang’e data for an overall 25,250 impact crater targets. The existing but inaccurate craters are combined with our labeled data to generate a larger dataset of craters. This data set is analyzed and compared with the common detection data. Third, deep learning detection methods are employed to detect impact craters. To address the problem attributed to the resolution of Chang’e data being too high, a quadtree decomposition is conducted. Lastly, a geographic information system is used to map the DEM data to 3D space and annotate the semantic information of the impact craters. In brief, a 3D model of the Moon with crater information is implemented based on Chang’e data in the Chang‘e reference frame, which is of high significance.