Alpine-type serpentinites from the Auckland Province—III. Petrography, mineralogy, petrochemistry, and petrogenesis

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Abstract
Serpentinisation of harzburgite at Wairere, and of both dunite and harzburgite in North Auckland, produced a chrysotile-lizardite assemblage plus minor brucite and magnetite. Associated mafic rocks include eucrite and bojite at Wairere and feIdspathic peridotites, olivine gabbros, olivine-free gabbros, and troctolites in North Auckland. Metasomatic changes have affected the chemistry and mineralogy of all rocks and have obscured an original, possibly calc-alkaline, igneous trend. The high crustal emplacement of serpentinite in the Auckland Province is believed to be the result of a persistent, moderate, tectonic compression originating before the Rangitata Orogeny (Jurassic-Cretaceous) and continuing into the Miocene.