Suchergebnisse

Studies, e.g. [1,2], reveal that the South-Pole Aitken (SPA) basin is unique, particularly because it is the deepest basin on the Moon and might be expected to expose the lunar mantle [3]. The innermost part of SPA is rich in high Ca-pyroxenes, except for some central crater peaks, where low Ca-pyroxenes dominate. No extensive olivine-rich areas are observed, implying a mantle rich in low Ca-pyroxenes instead of olivine [1, 3, 4]. Furthermore, thorium anomalies have been discovered in two craters within Aitken basin [5]. Here, we focus on the spectral analysis of one of the most interesting impact crater inside SPA, the Apollo basin. Recently, [6] published a detailed geological map of the area surrounding Apollo basin (35.69°S, 151.48°W; D~524 km), using morphology, stratigraphy, crater size-frequency distribution measurements, and Clementine spectral data to define the unit. Our work explores data from the M3 imaging spectrometer onboard Chandrayaan-1 [7] for this region. These analyses are part of the PLANMAP project, and the integration of the spectroscopical information with the results from [6] will permit to produce highly informative geological maps of the Moon [8]. This work is funded by the European Union's Horizon 2020 research grant agreement No 776276- PLANMAP. References [1] Ohtake, M. et al., 2014, GRL. [2] Moriarty, D.P. et al., 2018, JGR. [3] Dhingra, D., 2018, Geosciences. [4] Melosh, H. J., et al., 2017, Geology. [5] Lawrence, D.J. et al., 2000, JGR. [6] Ivanov, M.A., 2018, JGR. [7] Pieters et al., 2009, Current Science [8] https://www.planmap.eu/

H05 Hokusai (22.5°N–65°N, 0°–90°E) is one of the northern quadrangles of Mercury [1, 2]. It is characterized by different features, and includes several morpho-stratigraphic units. Smooth plains is the most widespread, covering ~43% of the entire quadrangle, followed by fresh crater material (~17%) and intercrater plains (~10%). The remaining part of the quadrangle contains intermediate plains (7%), degraded crater material (9%) and heavily degraded material (8%) [1]. Other morpho-stratigraphic units, such as smooth and hummocky crater floor material, account for a few percent [1]. Furthermore, this quadrangle includes part of the Hokusai ray system, the largest example on Mercury, and several pyroclastic deposits, including Nathair Facula, one of the highest-reflectance features observed on the planet, located at 480 km NE of Rachmaninoff crater [3, 4]. Spectral analysis based on specific spectral parameters represents a suitable approach to investigate compositional variations. We observed different spectral behavior among large parts of the morpho-stratigraphic units and surface features mapped by [1]. In particular, the units that show the highest spectral variability are the intermediate plains, smooth plains and fresh crater material, together with pyroclastic deposits and crater rays. Such a result indicates spectral variation related to the different units with implications for the geological processes on Mercury's surface. This work is funded by the European Union's Horizon 2020 research grant agreement No 776276- PLANMAP and by the Italian Space Agency (ASI) within the SIMBIO-SYS project (ASI-INAF agreement 2017-47-H.0). References [1] Wright et al., 2018, LPSC 2018 [2] https://planetarynames.wr.usgs.gov/Page/mercuryQuadMap [3] Rothery, D. et al., 2018 Oxford Research Encyclopedia of Planetary Science. Ed. [4] Procter, L. et al., 2010, Science 329.