Mare Basalts on the Apennine Front and the Mare Stratigraphy of the Apollo 15 Landing Site

Abstract

Olivine-nonnative mare basalts are present on the Apennine Front as crystalline particles and shocked or shock-melted fragments. Picritic basalts, which may be related to the olivine-nonnative basalts by olivine accumulation, not only occur on the Front but such samples so far recognized are confined to it. Mare volcanic and impact glasses also occur on the Front; all are olivine-normative, though none are quite the equivalent of the typical olivine-nonnative mare group. The quartz-nonnative mare basalts are not present (or are extremely rare) on the Front either as crystalline basalts or shocked or glass equivalents. These observations are consistent with the olivine-nonnative mare basalts being both local and the youngest flows at the site, and the fragments being emplaced on the Front by impacts.