Thermal history and early magmatism in the Moon

Abstract

Lunar heat-flow calculations are carried out for a model Moon in which (a) near-surface initial temperatures are very high (as the occurence of a surface anorthositic layer seems to require), and (b) heat-generating radionuclides are transported upward when melting occurs. Near-surface regions are found to cool and then experience a resurgence of high temperature, as radionuclide-rich magmas from the lunar interior accumulate near the surface. This peaking of near-surface temperature can be brought into correspondence with the episode of vulcanism (∼ 3.5 × 10 9 years ago) that gave rise to the basalts represented in the Apollo samples, if we assume relatively high lunar temperatures in early times (due to high initial temperatures, or high content of radioactive elements, or both).