Dunite 72417 - A chemical study and interpretation

Abstract

The rock selected for the study is one of the rare ultrabasic rocks, which seems to have survived early lunar differentiation. The Rb-Sr internal isochron for this dunite gave an age of about 4.55 AE. The dunite was sampled at Apollo 17, Station 2 from a single 10x20-cm clast incorporated into a KREEP-rich blue-gray breccia 72435, Boulder 3. Nine dunite samples were analyzed with the aid of instrumental and radiochemical neutron activation analysis procedures. Data for 27 elements are shown in a table. Attention is given to trapped liquid (magma), a garnet hypothesis, models for the dunite genesis, and magma compositions from which 15415 and 72417 crystallized.