  The process of lunar magma ocean solidification provides constraints on the
properties of distinct chemical reservoirs in the lunar mantle that formed
during the early evolution of the Moon. We use a combination of phase
equilibria models consistent with experimental results on lunar magma ocean
crystallization to study the effect of bulk silicate Moon composition on the
properties of lunar mantle reservoirs. We find that the densities and relative
proportions of these mantle reservoirs, in particular of the late forming
ilmenite bearing cumulates (IBC), strongly depend on the FeO content of the
bulk silicate Moon. This relation has implications for post-magma ocean mantle
dynamics and the mass distribution in the lunar interior, because the dense IBC
form at shallow depths but tend to sink towards the core mantle boundary. We
quantify the relations between bulk silicate Moon FeO content, IBC thickness
and bulk Moon density as well as mantle stratigraphy and bulk silicate Moon
moment of inertia to constrain the bulk silicate Moon FeO content and the
efficiency of IBC sinking. In combination with seismic and selenodetic
constraints on mantle stratigraphy, core radius, extent of the low velocity
zone at the core mantle boundary, considerations about the present day
selenotherm and the effects of reservoir mixing by convection our model
indicates that the bulk silicate Moon is only moderately enriched in FeO
compared to the Earths mantle and contains about 9.4 - 10.9 weight percent FeO
(with a lowermost limit of 8.3 weight percent and an uppermost limit of 11.9
weight percent). We also conclude that the observed bulk silicate Moon moment
of inertia requires incomplete sinking of the IBC layer by mantle convection:
only 20 - 60 percent of the IBC material might have reached the core mantle
boundary, while the rest either remained at the depth of origin or was mixed
into the middle mantle.
