Gamet compositions in metamorphic rocks and granites of Westland, New Zealand

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Abstract
Three distinctive garnet suites, derived respectively from Haast Schist, Fraser Formation gneiss, and granites, can be recognized in Westland rocks and alluvium. All have almandine as the major component but show the following characteristics: Haast Schist garnets have low Mg (MgO = 0.4–3.1%) and medium to low Ca (CaO = 4.8–12.0%) and Mn (MnO = 0.2–9.4%). Fraser Formation garnets have higher Mg (MgO = 4.9–11.3%) and generally low Ca (CaO = 1.4–2.8%; one with 6.4%) and Mn (MnO = 0.5–1.0%). Garnet from granites are often Mn-rich (MnO = 2.3–11.6%) and are low in Ca (CaO = 0.4–1.7%). Hornblendes in association with garnet in Haast Schist are mostly ferrotschermakites, with Al2O3 contents close to the maximum recorded in hornblende. The relationship of the Fraser Formation to the Haast Schist and the Greenland Formation is discussed; it does not appear to be related to these formations and may be allochthonous (transported masses of the Fiordland Complex?).