Spectral investigation of Mercury's pits' surroundings: Constraints on the planet's explosive activity

A Spectral Study of the Caloris Basin on Mercury and the Origin of Associated Volcanic Smooth Plains

“…A large number of spectral parameters can be used for the analysis of Mercury's surface and have already led to numerous results, notably concerning pyroclastic deposits and hollows (Barraud et al, 2020(Barraud et al, , 2021Besse et al, 2015Besse et al, , 2020Bott et al, 2019;Goudge et al, 2014;Zambon et al, 2022). In this study, we selected spectral parameters that, individually or in combination with each other, effectively distinguish the interior Caloris plains (HRP), the exterior Caloris plains (LBP) and the LRM (Table 1).…”

“…Results from the MESSENGER mission have identified different spectral color units (Denevi et al., 2009; Ernst et al., 2010; Murchie et al., 2015; Robinson et al., 2008) that are not systematically associated with geological units (Denevi et al., 2013; Murray et al., 1975; Spudis and Guest., 1988; Trask and Guest., 1975) or compositional units (Namur & Charlier, 2017; Nittler et al., 2020; Peplowski et al., 2015; Vander Kaaden et al., 2017; Weider et al., 2015). Among the numerous spectral color units (see Table 1 of Murchie et al., 2015 and D'Incecco et al., 2015) are: fresh crater materials characterized by brighter reflectance and slightly bluer spectral slopes than the average (Ernst et al., 2010), bright hollow materials showing in a significant way a higher reflectance and bluer slopes than surroundings (Barraud et al., 2020; Blewett et al., 2013), the red unit interpreted as pyroclastic vents with a relatively red spectra and high reflectance (Barraud et al., 2021; Ernst et al., 2010; Robinson et al., 2008), intermediate plains (Denevi et al., 2009), HRP, low‐reflectance blue plains (LBP) and low reflectance material (LRM). HRP have a steeper reflectance spectrum slope in the visible to near‐infrared domain than the planet's average and a high reflectance at 750 nm (20% higher than the global average).…”

“…In the originally published version of this article, the citations " Barraud et al, 2020Barraud et al, , 2021 were omitted from the first sentence of Section 3.1.3, "Parameters Highlighting Spectral Units." The sentence should read: "A large number of spectral parameters can be used for the analysis of Mercury's surface and have already led to numerous results, notably concerning pyroclastic deposits and hollows (Barraud et al, 2020(Barraud et al, , 2021Besse et al, 2015Besse et al, , 2020Bott et al, 2019;Goudge et al, 2014;Zambon et al, 2022)." Also, in Table 4, In the third column of the first row under the heading "Level 2 bis (L2 bis)," the units 0.034824 ≤ R750 ≤ 0.037080 should be 0.034910 ≤ R750 ≤ 0.037080.…”

A Geostratigraphic Map of the Rachmaninoff Basin Area: Integrating Morphostratigraphic and Spectral Units on Mercury

“…Low‐reflectance material is hypothesized to be graphite‐rich remnants of Mercury's primary crust (Klima et al., 2018; Vander Kaaden & McCubbin, 2015). Furthermore, many putative pyroclastic deposits on Mercury exhibit a downturn toward UV wavelengths (i.e., steeper UV slopes: Barraud et al., 2021; Goudge et al., 2014). Therefore, the overall shapes of the spectra vary on spatial scales such that characteristic spectra of certain geological features can be identified (Zambon et al., 2022).…”

“…Rachmaninoff is a 290 km‐diameter peak ring basin with a relatively undegraded appearance and an ejecta deposit that superposes nearby smooth plains (Marchi et al., 2011; Prockter et al., 2010; Wright et al., 2019; Wright, Byrne, & Rothery, 2021), indicating that the impact postdates the end of large‐volume effusive volcanism in the region (Byrne et al., 2016). Rachmaninoff contains low‐reflectance material (Denevi et al., 2009; Klima et al., 2018; Marchi et al., 2011; Prockter et al., 2010), which contrasts starkly with the high‐reflectance, redder spectral signature of Nathair Facula, the largest putative explosive volcanic deposit on Mercury (Barraud et al., 2021; Besse et al., 2020; Kerber et al., 2011; Leon‐Dasi et al., 2023; Rothery et al., 2021), nearby to the northeast. The interior of Rachmaninoff contains Mercury's lowest surface elevation (Becker et al., 2016) and the planet's thinnest crust (Beuthe et al., 2020).…”