Lermontov crater on Mercury: Geology, morphology and spectral properties of the coexisting hollows and pyroclastic deposits
Journal
Date Issued
2021
Author(s)
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Semenzato, A.
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Marzo, G. A.
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Massironi, M.
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.
Volume
195
Start page
105136
Issn Identifier
0032-0633
Ads BibCode
2021P&SS..19505136P
Rights
open.access
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