Colloquium: Bradley L. Jolliff

Abstract: Bits and pieces of rocks found among Apollo samples provide evidence of compositionally and petrologically evolved rock types such as alkali anorthosite, monzogabbro, and granite or rhyolite. The geologic setting and mechanism of formation of these materials, however, remains obscure. Did they form as very late-stage fractionates of magmas associated with other rock types and in very small quantities, or did they form in some cases as large, segregated rock bodies? Recent remote sensing by the Lunar Reconnaissance Orbiter, combined with Lunar Prospector gamma-ray data, indicates relatively large (for the Moon) bodies of these rock types in the shallow crust and at the surface. Examples to be discussed include rocks exposed by Aristarchus Crater in Oceanus Procellarum and at the Compton-Belkovich site, in the northern far-side hemisphere.

Bradley L. Jolliff, Research Professor
Department of Earth and Planetary Sciences, Washington University in St. Louis