Multiple Mantle Sources of High‐Magnesium Terranes on Mercury

Abstract

The composition of the silicate portion of Mercury yields important constraints needed to resolve the possible building blocks and geodynamics (e.g., magma ocean differentiation and volcanism) of this single-plate planet. With an extraordinarily large iron-rich core and a thin silicate mantle (Hauck et al., 2013), Mercury has a secondary crust that was mainly formed by mantle-derived volcanic deposits (Denevi, Ernst, et al., 2018). The crust of Mercury contains much higher contents of Mg, S, and C, but lower contents of Al, Ca, and Fe than the other terrestrial planets and the Moon (McCoy et al., 2018;Nittler & Weider, 2019), suggesting that the oxygen fugacity of Mercury materials is much lower (McCubbin et al., 2012;Zolotov et al., 2013). Partial melting of the highly reduced mantle of Mercury produces iron-poor magma, which is relatively buoyant at most depths of the mantle (Vander Kaaden & McCubbin, 2015), driving widespread volcanism on the surface with high volume fluxes

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

“…The time between the two volcanic events would be the reason for the spectral and compositional differences between the interior and exterior plains and it is clear that an evolution of magmatism processes occurred during this time. Understanding this evolution will clarify our understanding of hermean magmatism in link with impact formation, including the nature and depth of volcanic sources and the degree of partial melting (Wang et al., 2022; Weider et al., 2013).…”

“…Decreasing the temperature through time implies that the magma formed under a lower melt fraction and/or at a lower depth. We focus this study on Caloris and its associated volcanic plains but for any comparison with other basins and their associated volcanic plains it is important to take into account that although the degree of partial melting decreases over time on Mercury, mantle disrupting events such as major impacts can reverse this trend locally (Wang et al., 2022).…”