An Appinitic Intrusion-Breccia at Kilkenny, Maas, Co. Donegal

Abstract

AbstractAn intrusion-breccia filling a pipe is made of two parts, one of facetted quartzite fragments in a granophyric matrix, the other of calc-silicate-rock fragments in an appinitic matrix. The quartzite fragments are derived from a horizon at least 1,000 ft. below the breccia level, the calc-silicate-rock fragments are local. The mechanism of emplacement of the breccia is considered to be similar to that proposed by H. Cloos for the Swabian tuff-pipes. Neither the granophyre nor the appinite of the Kilkenny pipe is regarded as of magmatic origin.