A Pyroxene – Hornfels from the Basic Plutonic Complex, Co. Tyrone, Ireland

Abstract

SummaryA basic augite-hypersthene-hornfels, which escaped a subsequent regional amphibolite facies metamorphism, is preserved adjacent to a gabbroic intrusion of the Basic Plutonic Complex. The hornfels and two dolerites have been analysed and their compositions compared with similar rocks from Duluth and Skye. It appears that Si, Na and K have been removed from the dolerites, and the resultant hornfels relatively enriched in Fe, Mg, Ti and Ca.