Explosive lunar fission above a large low-velocity province

Abstract The giant impact hypothesis for the Moon’s origin has had difficulty explaining the nearly identical isotopic compositions of Moon rocks and rocks from Earth’s silicate mantle and crust. These similarities are instead more compatible with the Darwin-Wise hypothesis that the Moon arose by fission of a rapidly spinning Earth. To overcome problems with the fission model concerning structural stability and angular momentum conservation, some authors suggested that lunar fission was feasible on a more slowly rotating Earth if assisted by a nuclear explosion near the core-mantle boundary. In this light we consider the possible roles of the large low-velocity provinces (LLVPs). These long-lived structures have been implicated in diverse geophysical processes ranging from deep mantle plumes to continental breakup and mass extinction events. While the LLVPs have been seen as possible remnants of the giant impactor, we propose that one of them was the site of lunar ejection. Internal heating of the liquid core is suggested to have given rise to an equatorial belt just under the core-mantle boundary analogous to the one recently detected by Ma and Tkalčić [Sci Adv 10(35):eadn5562, 2024]. Upwellings of heat and volatiles from this belt then generated two antipodal, equatorial bulges: the precursors of the Pacific and African LLVPs. Prior to the emergence of plate tectonics, core heat was mainly dissipated by networks of deep mantle plumes extending above the proto-LLVPs. These plume networks represent conduits of weakened mantle through which proto-lunar materials could later rise in a focused ejection. Continuing heat buildup in the core eventually triggered a cataclysmic explosion in the Pacific proto-LLVP, possibly analogous to a planetary-scale kimberlite eruption. This explosion launched LLVP and overlying mantle material into a low Earth orbit, where it coalesced to form the Moon. Some possible sources of additional energy to power the explosion are considered, including nuclear fission, bolide impacts and a hypothetical gravitational decay process culminating in a ‘Ʌ event’.