A basal magma ocean dynamo to explain the early lunar magnetic field

作者：Scheinberg Aaron L^*; Soderlund Krista M; Elkins Tanton Linda T

来源：Earth and Planetary Science Letters, 2018, 492: 144-151.

DOI：10.1016/j.epsl.2018.04.015

• lunar magnetism
• geodynamo
• magma ocean
• geodynamics

The source of the ancient lunar magnetic field is an unsolved problem in the Moon's evolution. Theoretical work invoking a core dynamo has been unable to explain the magnitude of the observed field, falling instead one to two orders of magnitude below it. Since surface magnetic field strength is highly sensitive to the depth and size of the dynamo region, we instead hypothesize that the early lunar dynamo was driven by convection in a basal magma ocean formed from the final stages of an early lunar magma ocean; this material is expected to be dense, radioactive, and metalliferous. Here we use numerical convection models to predict the longevity and heat flow of such a basal magma ocean and use scaling laws to estimate the resulting magnetic field strength. We show that, if sufficiently electrically conducting, a magma ocean could have produced an early dynamo with surface fields consistent with the paleomagnetic observations.

• 出版日期2018-6-15