The Distribution of Peak‐Ring Basins on Mercury and Their Correlation With the High‐Mg/Si Terrane

Abstract

AbstractA catalog of mercurian craters that retain their central peak or peak‐ring structure was created to aid target prioritization for the Mercury Imaging X‐ray Spectrometer (MIXS), now on its way to Mercury aboard BepiColombo. Preliminary analysis of the MIXS crater catalog suggested a potential spatial correlation between an abnormally high spatial density of peak‐ring basins and a region of Mercury with elevated Mg/Si values (High‐Magnesium Terrane [HMT]). Robust statistical analysis of previously published crater catalogs confirmed that the spatial correlation exists, with an overall confidence level of 97.7%, specifically between peak‐ring basins and the HMT, delineated by a contour of Mg/Si = mean + 2σ = 0.648. Applying empirical impact cratering scaling laws to the 15 basins intersecting the HMT suggested that all have excavated material from ~13 to 20 km depth. None of the basins excavated mantle material, predicting instead that deep crustal material contains elevated Mg/Si material. However, five of the basins are predicted to have melted underlying mantle material, which might be a contributing factor in the elevated Mg/Si signature. In the absence of resolvable volcanic features associated with the rise of basaltic melts from the mantle, we favor excavation of deep crustal, high Mg/Si material. MIXS‐T is capable of spatially resolving individual features associated with peak‐ring basins and it is proposed that the 15 basins within the HMT are prioritized targets for MIXS, to test the hypothesis of exposed deep‐crustal material.