Carboniferous metamorphism and partial melting of the Greenland Group in the Jackson River valley, south Westland
MetadataShow full item record
The peak conditions and timing of metamorphism have been determined for the early Paleozoic Greenland Group in south Westland, New Zealand. The Greenland Group, which is the most extensive pre-Cenozoic unit west of the Alpine Fault in Westland, is dominated by greenschist facies greywacke and argillite. However, in the Jackson River valley this unit comprises amphibolite facies pelitic and psammitic gneisses. Psammitic horizons are dominated by biotite, plagioclase and quartz. Pelitic horizons have similar mineralogy but also contain sillimanite and K-feldspar, as well as boudinaged K-feldspar-bearing leucosomes. Conventional geothermometry and thermodynamic modelling indicate that peak metamorphism occurred between 660 and 700 °C and 3.5 and 6.0 kbar. The timing of this moderately high-T/low-P event is constrained to be mid-Paleozoic by U-Th-Pb dating of overgrowths on detrital zircon (334 ± 18 Ma) and confirmed to be Carboniferous by a single population of monazite grains (343 ± 3 Ma). Greenland Group metamorphism in the Jackson River valley may represent Carboniferous high crustal heat flow in the Gondwana margin hinterland while crustal thickening was occurring closer to the subduction zone.
Showing items related by title, author, creator and subject.
Cretaceous metamorphism, magmatism and shearing in the Waipuna Valley, directly south of the Reefton GoldfieldRitchie, T.; Scott, J.; Muhling, J.; Kennedy, Allen (2015)Rocks in the Waipuna Valley in Westland show that the area immediately south of the Reefton Goldfield has been dramatically affected by Cretaceous tectonism. The main lithology in the Waipuna Valley is metasedimentary ...
Provenance record from Mesoproterozoic-Cambrian sediments of Peary Land, North Greenland: Implications for the ice-covered Greenland Shield and Laurentian palaeogeographyKirkland, Chris; Pease, V.; Whitehouse, M.; Ineson, J. (2009)In North Greenland, Precambrian crystalline basement forms restricted outcrops bordering the Inland Ice. The coverage and nature of this basement is of key importance in understanding the evolution of the Greenland Shield ...
Burton, Graeme; Rosman, Kevin; Candelone, Jean; Burn, Laurie; Boutron, C.; Hong, S. (2007)We present here a time series of Pb and Sr isotopes in Greenland ice over the last glacial cycle. The data were obtained by analysing the dust contained in small (less than 10 g) aliquots of sections of the GRIP (European ...