Geochemistry, mineralogy, and metamorphic history of kyanite‐orthoamphibole‐bearing Alpine Fault mylonite, South Westland, New Zealand

Abstract Mylonite outcropping in the Alpine Fault Zone at Makawhio River, South Westland, shows mineralogy unlike rocks found elsewhere in the Haast Schist. The Makawhio mylonites comprise kyanite‐orthoamphibole hornblendite, garnet amphibolite, chlorite‐hornblende schist, kyanite‐plagioclase schist, and talc‐tremolite rocks, are characterised by ultrabasic to intermediate chemistry, show extreme enrichment in Cr and Ni, and collectively include kyanite, margarite, fuchsite, scapolite, and the first reported occurrence of gedrite and anthophyllite from the Eastern Province. These unusual mylonites form a pod‐like body enveloped by chlorite‐hornblende schist within Torlesse‐derived metasediments. The geochemistry and mineralogy of the Makawhio rocks suggests an origin as a veined ophiolitic rock metasomatised before or during upper amphibolite facies Alpine Schist metamorphism and mylonitisation, resulting in a localised occurrence of rocks atypical of the Haast Schist overall. These kyanite‐bearing, metas...