We present a multidisciplinary analysis of Lermontov crater, located at 15.24°N, −48.94°E in the Kuiper quadrangle of Mercury. By means of MESSENGER multiband MDIS-WAC and monochrome MDIS-NAC images, we prepare a high-resolution geological map of the crater and its closest surroundings, highlighting the presence of coexisting hollows and pyroclastic deposits on its floor. On the photometrically corrected MDIS-WAC multiband dataset, we apply an unsupervised clustering technique that spectrally separates the different materials located both inside and outside Lermontov crater. We observe that the pyroclastic deposits located on the crater's floor have a steep, red spectral behaviour dominated by the presence of a mixture of various pyroxenes containing Ti and Ni. On the contrary, the vents’ rims are characterised by several hollows whose spectral slope is bluer than that of the pyroclastic deposits. By comparing the vent hollows to the hollows located farther out on the crater floor, we observe a steeper 0.62–0.82 ​μm spectral trend for those within the vents. The vent hollows’ spectrum is more similar to the pyroclastic one in the above mentioned wavelength range. In addition, the vent hollows 0.55 ​μm absorption band could be related to CaS, while the small differences in slope at 0.48 ​μm and 0.62 ​μm could be due to the presence of other volatiles compounds, such as MgS or chlorides. When compared to hollows located in other hermean geological settings, Lermontov hollows are characterised by steeper spectra. This supports the interpretation that when hollows form, their bright deposits do not completely overwrite the spectral signature of the surrounding terrain, and their spectroscopic appearance is mixed with the composition of the terrain where they form.

Lermontov crater on Mercury: Geology, morphology and spectral properties of the coexisting hollows and pyroclastic deposits

Semenzato A.;Munaretto G.;Massironi M.
2020

Abstract

We present a multidisciplinary analysis of Lermontov crater, located at 15.24°N, −48.94°E in the Kuiper quadrangle of Mercury. By means of MESSENGER multiband MDIS-WAC and monochrome MDIS-NAC images, we prepare a high-resolution geological map of the crater and its closest surroundings, highlighting the presence of coexisting hollows and pyroclastic deposits on its floor. On the photometrically corrected MDIS-WAC multiband dataset, we apply an unsupervised clustering technique that spectrally separates the different materials located both inside and outside Lermontov crater. We observe that the pyroclastic deposits located on the crater's floor have a steep, red spectral behaviour dominated by the presence of a mixture of various pyroxenes containing Ti and Ni. On the contrary, the vents’ rims are characterised by several hollows whose spectral slope is bluer than that of the pyroclastic deposits. By comparing the vent hollows to the hollows located farther out on the crater floor, we observe a steeper 0.62–0.82 ​μm spectral trend for those within the vents. The vent hollows’ spectrum is more similar to the pyroclastic one in the above mentioned wavelength range. In addition, the vent hollows 0.55 ​μm absorption band could be related to CaS, while the small differences in slope at 0.48 ​μm and 0.62 ​μm could be due to the presence of other volatiles compounds, such as MgS or chlorides. When compared to hollows located in other hermean geological settings, Lermontov hollows are characterised by steeper spectra. This supports the interpretation that when hollows form, their bright deposits do not completely overwrite the spectral signature of the surrounding terrain, and their spectroscopic appearance is mixed with the composition of the terrain where they form.
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/3361055
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 12
  • ???jsp.display-item.citation.isi??? 9
social impact