The Ardara granitic diapir of County Donegal, Ireland

Abstract

The composite diapir of Ardara, County Donegal, foreibly displaced contact-altered Dalradian rocks of its envelope by folding, thrusting and shearing. The intrusion consists of a granodiorite core surrounded by a mantle of course tonalite. The outer part of the core is made up, in the north, of contaminated quartz-diorite and, in the south, of less contaminated granodiorite. These rocks, and the tonalite, are well foliated. The central part of the core is composed of uncontaminated and unfoliated biotite-granodiorite