Constraints on the Temperature and Mineralogy of the Moon from a Joint Inversion of Apollo Seismic, Geodetic Data and Lp-Clementine Gravity Data

We show the results of a joint inversion of most of the geophysical data gathered for the Moon by the Apollo, Lunar Prospector and Clementine missions. These data constrain different parts of the Moon interior : the crust and moon upper mantle are mainly constrained by seismic and heat flux data, while the very deep Moon interior is constrained by geodetic data. Our results show that a joint analysis of seismic and heat-flux data, in the PKT terrannes, favors a crust in the range of 30-35 km, thinner than proposed in the studies published in the seventieth. More detailed analysis, taking into account lateral variations of the crust, confirm such value. Deeper, we generally find temperature of 1073K (elastic lithosphere limit) and 1473K (thermal lithosphere limit) for radius of about 1400 km and 1000 km, comparable to the depth found in thermal evolution models. Our temperature profiles suggest 70% depletion for the upper and lower mantle compared to the Earth reference of 25.7 ppb. Finally, taking a mean crustal thickness of 40 km with 1010 ppb in Th and our mantle value for the depletion, we find a bulk Th and U abundance comparable to the Earth values within the error bars, and even possibly smaller. Constraints on the core size and lower mantle are also provided, by a joint inversion of the seismic models, of the inertia factor, mean density and k2 Love number. Based on this study, our Moon model is a 40 km thick anorthositic crust with a pyroxenite cold mantle (of bulk composition 6.4% in Al2O3, 4.9% in CaO, and 13.3% in FeO ) with an magnesian model for the bulk composition of the Moon lower mantle.