The igneous rocks of the Boganclogh area, N.E. Scotland

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Abstract
Synopsis: The Boganclogh intrusion, which appears to be a westerly extension of the Insch mass, is chemically and petrologically subdivided into three principal units which occupy roughly east-west belts. Ultrabasic Group. This consists of serpentinites and peridotites and is probably related to the Lower Zone cumulates of the Insch mass. Ferrodiorite Group. This is believed to be equivalent to the Insch Upper Zone. The high value of the Sr 87 /Sr 86 isotopic ratio in the ferrodiorites at the time of crystallization (0.711) is ascribed to isotopic exchange with Sr in the country rocks, as has been proposed for the Insch Upper Zone. Quartz–Biotite Norite Group. These rocks form a central belt and are distinct from any of the Insch material. However, a chemical and isotopic comparison with similar rocks from the Haddo House, Arnage and Morven-Cabrach intrusions indicates a common mode of origin, probably involving introduction of water from country rocks into the regional basic magma.