Abstract
Synopsis: Basic igneous rocks of the Haddo House and Arnage districts consist of olivine-norites, and quartz-norites which include uralitised and xenolithic types. No layered sequence is observed in the basic igneous rocks of Haddo House and Arnage and their petrochemistry suggests that some water must have entered the magma in that area producing hypersthene- and quartz-normative rock types. This would account for the differences observed between the igneous rocks of Haddo and Arnage and those in other parts of north-east Scotland which were intruded at the same time, and might be products of the same parental magma.