Physical Properties and Internal Structure of the Central Region of the Moon

Abstract One of the pivoting problems geochemistry and geophysics Moon is structure its central region, i.e., core adjacent transition layer located at boundary between solid mantle liquid or partially molten core. The chemical composition internal region were simulated based on joint inversion seismic, selenophysical, geochemical parameters that are not directly interrelated. solution inverse problem Bayesian approach use Markov chain Monte Carlo algorithm in combination with method Gibbs free energy minimization. results show radius Moon’s about 500–550 km. thickness radii outer inner cores relatively weakly depend models bulk silicate different contents refractory oxides. portion enriched FeO (12–13 wt %, ~ 1.5 × BSE) depleted MgO (Mg# 79–81) relative to Earth (BSE), which conflict possibility formation from Earth’s primitive does find an adequate explanation current canonical non-canonical origin Moon. SiO 2 concentrations all zones lunar vary insignificantly amount 52–53 predominant mineral upper low-Ca orthopyroxene but olivine. With respect Al O 3 , stratified, a content higher lower than overlying shells. surrounding 200–250 km thick. within 50–250 km, most probable ~300–350 physical characteristics compared experimental measurements density speed sound Fe(Ni)–S–C–Si alloys. If seismic model V P = 4100 ± 200 m/s (Weber et al., 2011) reasonably reliable, then this uncertainty range best agreement values 3900–4100 Fe(Ni)–S alloys, sulfur up ~10 % 6200–7000 kg/m as well inverted velocity Fe–Ni–C Fe–N–Si alloys 5 GPa exceed estimates core, indicates carbon silicon can hardly be dominant light elements Fe(Ni) (possibly insignificant elements: carbon) presumably has 7500–7700 . difference ?? 500–1000 explained by their composition.