Terminology of postcumulus processes and products in the Rhum layered intrusion

The terminology of cumulates is discussed with particular reference to postcumulus processes as exemplified by the Rhum layered intrusion. The history of the terms orthocumulate, adcumulate, heteradcumulate and harrisitic cumulate is reviewed, and some modifications to the classification scheme proposed by Irvine (1982) are suggested. Possible mechanisms of adcumulus growth are considered and, on balance, the Rhum evidence confirms the view that postcumulus cementation occurred at a relatively early stage, while the intercumulus melt was in effective contact with the main body of magma.