On lunar asymmetries 2. Origin and distribution of mare basalts and mascons

A novel mechanism is proposed for the emplacement of mare basalts and the formation of mascons that does not involve melting or remelting of the source region. The source magmas are the remnants of the primordial lunar magma ocean and are rich in incompatible elements, including radioactive isotopes; potassium, rare earth elements, and phosphorus (KREEP); and volatiles. Exsolution of volatiles as the magmas cooled and crystallized (a process …