An Effusive Lunar Dome Near Fracastorius Crater: Spectral and Morphometric Properties

We examine a dome within the boundary between Fracastorius crater and Mare Nectaris. The dome has a noticeable vent structure and appears to be perpendicular to wrinkle ridges in the southern Mare Nectaris basin. The spectral signature of this dome, derived from Clementine UVVIS and Chandrayaan-1 M3 reflectance data, revealed that Fracastorius has low TiO2 content and primarily basaltic material. Using altimeter data, we measured the dome diameter to be 28.6 km, with a dome height of 241.5 m, and a flank slope of 1°. Based on rheological modeling of the dome and a viscoelastic model of the presumed feeder dike, we obtained a magma viscosity of 3.1 × 105 Pa s, an effusion rate of 5.9 m3 s−1, a duration of multiple effusion processes of 4.15 years, and a magma rise speed of 2.1 × 10−4 m s−1. From these measurements, we estimate the feeder dike geometry to have a horizontal dike length of 234 km and a width of 11.8 m. A comparison of the Fracastorius dome with other noted lunar domes with similar morphometric properties reveal similar magma viscosities to domes found near craters Mee, Milichius and Petavius.