The Marginal Rocks of the Cairnsmore of Carsphairn Complex

Abstract

The marginal rocks of this intrusion were described briefly in a paper dealing with the Cairnsmore complex. The intrusion is composite, consisting of a central granite, and successive zones of acid hybrid, tonalite, and basic hybrid. The complex began with the intrusion of gabbro, and when crystallized, but still ata high temperature, it was followed by the tonalite with the production of the basic hybrids. The original basic intrusion is nowhere found in an unaltered condition but is now represented by the “dioritic” lenses. It is seen then that the outermost zone of the intrusion uncontaminated by the incorporation of the sedimentary country rocks is itself a hybrid resulting from the intrusion of tonalite in the original gabbro. In the earlier paper it was suggested that the character of these marginal rocks was due to the combined effects of sedimentary contamination and igneous hybridization.