The High-Th Oval Region of the Moon

The formation of the lunar high-Th oval region (HTOR) is presently envisioned as requiring lateral as well as vertical migration of Th and other KREEPy elements. A giant Procellarum impact event could have affected the development of the HTOR through the removal of the overlying crust or the deep injection of heat; such an impact might trigger a major differentiation event, such as mantle turnover involving material from the deep interior of the moon.