Explosive Moon Origin above a Large Low-Velocity Province

Two outstanding problems in the early evolution of the Earth concern the origins of the Moon and of the two large low-velocity provinces sitting on the core-mantle boundary. Evidence from moon rocks indicates that the geochemical compositions of the Moon and the Earth’s silicate mantle are nearly identical. This is difficult to explain with the giant impact hypothesis, but compatible with the older theory that the Moon arose by fission from a rapidly spinning Earth. To overcome problems with angular momentum in the fission model, it was recently proposed that the Moon separation was assisted by a large nuclear explosion occurring near the core-mantle boundary. It is unclear, however, whether such a ‘deep georeactor’ ever existed. Here we draw attention to an alternative energy source and mechanism for the Moon ejection. Theoretical and observational evidence suggests that all bodies generate internal heat at the rate –UH0, where U is the internal gravitational potential energy and H0 is the Hubble constant. With this process, the hottest region in the proto-Earth would have been the outer core. In our model, solar tides acting on the liquid outer core focused this energy in two equatorial bulges on the core-mantle boundary, which were the precursors of the two large low-velocity provinces. Prior to the existence of convective plate tectonics and deep mantle plumes, this heat would have been trapped in these structures by the overlying mantle. Over a period of 107–108 years, temperatures and pressures steadily rose inside of them until one exploded, launching the overlying proto-lunar materials into a low orbit. The Moon expulsion is suggested to have then catalyzed a series of volcanic events shaping the Earth’s geology and life, including the origin of plate tectonics and the formation of the large igneous provinces.