Long-Lasting Volcanism of the Moon Aided by the Switch in Dominant Mechanisms of Magma Ascent: Role of Localized Radioactive Enrichment in a Numerical Model of Magmatism and Mantle Convection

Abstract

Significant volcanic activity continued for billions of years since 3.5–4 Gyr ago in the Procellarum KREEP Terrane (PKT) of the Moon, but not so significant outside the PKT. To understand this volcanic history, we developed a 2-D numerical model of magmatism and mantle convection; the effects of the PKT on lunar evolution are considered by initially imposing a region of localized radioactive enrichment. The calculated volcanism is driven by two different mechanisms. Early volcanism occurs when magma generated in the deep mantle by internal heating ascends to the surface as partially molten plumes. The basaltic blobs in the uppermost mantle formed by this magmatism then sink into the deep mantle, triggering further plumes that cause a resurgence of volcanism in its later history. Our model suggests that later plumes caused by sinking basaltic blobs are the cause of the long-lasting volcanism in the PKT.