Lunar domes in Mare Undarum: Spectral and morphometric properties, eruption conditions, and mode of emplacement

Abstract

In this study we examine five lunar domes in Mare Undarum. Four domes termed Condorcet 1–4 are located between the craters Condorcet P and Dubiago, immediately east of Dubiago V and W. The fifth dome, termed Dubiago 3, is located about 35 km further south. The region under study is situated in a major trough concentric to the Crisium basin. The domes Condorcet 1–3 are aligned radially with respect to the Crisium basin. Similar dome configurations aligned radial to major impact basins are known from other lunar mare dome fields. The spectral signature of the domes derived from Clementine UV/VIS imagery reveals that they consist of basaltic lava with a low TiO 2 content below 2 wt% and with a FeO content around 10 wt%. Three examined domes exhibit highland components in their soils, which we attribute to lateral mixing between the material in the mare ponds and the surrounding highland material due to random impacts. All five domes have moderate diameters between 10 and 12 km. Condorcet 1–3 are similar to effusive domes of intermediate flank slope between 1 ∘ and 2 ∘ like those situated in the Hortensius/Milichius/T. Mayer region, while Condorcet 4 has an exceptionally steep flank slope of 2 . 8 ∘ and a large volume. With its low flank slope of 0 . 9 ∘ , the dome Dubiago 3 is morphometrically very similar to a known intrusive dome in the west of Mare Serenitatis. Hence, this structure is possibly of intrusive origin, but with the available data an effusive origin cannot be ruled out. Based on a rheologic model, we infer the physical conditions under which the domes were formed (lava viscosity, effusion rate, magma rise speed) as well as the geometries of the feeder dikes.