Publications
° Hollis, J.A., Clarke,
G.L., Klepeis, K.A., Daczko, N.R. and Ireland, T.R., 2004.
The regional significance of Cretaceous magmatism and metamorphism in Fiordland,
New Zealand, from U Pb zircon geochronology. Journal of Metamorphic Geology,
22, 607-627.
Abstract
The western Fiordland Orthogneiss (WFO) is an extensive composite metagabbroic
to dioritic arc
batholith that was emplaced at c. 20–25 km crustal depth into Palaeozoic
and Mesozoic gneiss during collision and accretion of the arc with the Mesozoic
Pacific Gondwana margin. Sensitive high-resolution ion microprobe U–Pb zircon
data from central and northern Fiordland indicate that WFO plutons were emplaced
throughout the early Cretaceous (123.6 ± 3.0, 121.8 ± 1.7,
120.0 ± 2.6 and 115.6 ± 2.4 Ma). Emplacement of the WFO synchronous
with regional deformation and collisionalstyle orogenesis is illustrated
by (i) coeval ages of a post-D1 dyke (123.6 ± 3.0 Ma) and its host
pluton (121.8 ± 1.7 Ma) at Mt Daniel and (ii) coeval ages of pluton
emplacement and metamorphism/ deformation of proximal paragneiss in George
and Doubtful Sounds. The coincidence emplacement and metamorphic ages indicate
that the WFO was regionally significant as a heat source for amphibolite to
granulite facies metamorphism. The age spectra of detrital zircon populations
were characterized for four paragneiss samples. A paragneiss from Doubtful
Sound shows a similar age spectrum to other central Fiordland and Westland
paragneiss and SE Australian Ordovician sedimentary rocks, with age peaks
at 600–500 and 1100–900 Ma, a smaller peak at c. 1400 Ma, and a minor Archean
component. Similarly, one sample of the George Sound paragneiss has a significant
Palaeozoic to Archean age spectrum, however zircon populations from the George
Sound paragneiss are dominated by Permo-Triassic components and thus are
markedly different from any of those previously studied in Fiordland.
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ARC Centre of Excellence for Core to Crust Fluid Systems