New Zealand Journal of Geology and Geophysics abstracts

---

Thermobarometry of the Charleston Metamorphic Group and implications for the evolution of the Paparoa Metamorphic Core Complex, New Zealand

P. J. WHITE

Institute of Geological and Nuclear Sciences Ltd
P.O. Box 2225
Auckland, New Zealand*

*Present address: Kingston Morrison Limited, P.O. Box 9806, Newmarket, Auckland, New Zealand.

Abstract  The Charleston Metamorphic Group in the central Paparoa Range, southwest Nelson, New Zealand, comprises metasedimentary and granitoid lithologies that have been metamorphosed to sillimanite-almandine conditions. Mineral assemblages and thermobarometric calculations indicate metamorphic temperatures and pressures of c. 600 (+/-50)deg.C and 4 (+/-1) kbar, respectively. A K-feldspar-sillimanite isograd mapped in pelitic gneisses indicates that metamorphic grade increases to the southwest, though this is not verified by thermobarometry results, which vary little throughout the entire range. A strong foliation is present in all lithologies. This foliation is folded but typically strikes between north and northeast.

The gneisses are intruded by several postmetamorphic granitoids, which in places retain their primary magmatic foliation (commonly striking between north and west), are unfolded and unmetamorphosed. These granitoids are distinct from the orthogneisses within Charleston Metamorphic Group. Together, the granitoids and gneisses comprise the Paparoa Metamorphic Core Complex, which was uplifted and unroofed in the mid Cretaceous, when estimated geothermal gradients were 50-90deg.C/km and uplift rates were 0.6-1.0 mm/a.

Keywords  Paparoa Range; Paparoa Metamorphic Core Complex; Charleston Metamorphic Group; Karamea Suite; Rahu Suite; thermobarometry; metamorphism; deformation

PDF file of entire paper: medium quality (1488K); (scanned from paper original: notes about this process)

---

This year's abstracts | Journal home page | All abstracts | Publishing home page