The Origin of the Girvan-Ballantrae Beerbachites

Abstract

AbstractThe mode of occurrence and petrography of a group of pyroxene- hornblende-granulites (beerbachites), found only in association with serpentinized peridotite, are described. The beerbachites are regarded as contact altered lavas and basic intrusions which formed the lower levels of a thick series of Ordovician volcanics. Peridotite, intruded into the base of the volcanic pile, disrupted and thermally metamosphosed the lavas and intrusions which appear as inclusions in the serpentinized peridotite. The present contacts between serpentinite and adjacent unmetamorphosed rocks are secondary in origin.