Analyses of chromian spinels from New Zealand peridotites

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Auer, A.; Mortimer, N. 2014 Analyses of chromian spinels from New Zealand peridotites. Lower Hutt, N.Z.: GNS Science. GNS Science report 2014/19 17 p.

Abstract: In this report we present 58 new major and minor element electron microprobe analyses of chromian spinels from three New Zealand peridotite units: Dun Mountain Ultramafics Group, Surville Serpentinite and North Auckland Serpentinites. We compare these with published and unpublished major and minor element analyses of other New Zealand chromian spinels (excluding those from mantle xenoliths). The analyses were done to try and establish whether the North Auckland Serpentinites originated from the Dun Mountain Ultramafics Group or from the Surville Serpentinite of the Cretaceous-Oligocene Northland Allochthon. Although the Dun Mountain and Surville spinels have generally separate and distinctive compositions, the analysed spinels from the North Auckland Serpentinites do not clearly match one or other reference group. Different analytical techniques and/or more samples will be needed to unambiguously establish the origin of the North Auckland Serpentinites. (auth)