gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1992.056.384.04 Petrology and Geochemistry Significance of the Cumulate Mineralogy of the Belhelvie Mafic-Ultramafic Intrusion—Comments on: Silicate Mineralogy of the Belhelvie Cumulates, NE Scotland, by W. J. Wadsworth Boyd R. Geological Survey of Norway, P.O. Box 3006, N-7002 Trondheim, Norway Ashcroft W. A. Department of Geology and Petroleum Geology, University of Aberdeen, Aberdeen AB9 2UE, Scotland 9 1992 56 384 329 333 17 5 1991 9 1 1992 Copyright © 1992, The Mineralogical Society 1992 Abstract

New data on the composition of cumulus phases in the Belhelvie intrusion presented by Wadsworth (1991) are discussed in the light of existing data and of knowledge on the form and internal structure of the intrusion. The relevance of the Rustenburg Layered suite of the Bushveld Complex as a model for the ‘single intrusion’ hypothesis for the layered basic intrusions in NE Scotland is examined: current knowledge of the Rustenburg Layered Suite and related intrusions suggests that similar crystallisation sequences of cumulus phases and ranges of cryptic variation do not give any case for a single intrusion hypothesis.

 Keywords cryptic variation cumulates Belhelvie Scotland