New Zealand Journal of Geology and Geophysics abstracts
Cretaceous-Tertiary tectonic history of the Fiordland margin,
New Zealand
RAY WOOD
RICK HERZER
RUPERT SUTHERLAND
ANNE MELHUISH
Institute of Geological & Nuclear Sciences
P.O Box 30 368
Lower Hutt, New Zealand
email: r.wood@gns.cri.nz
Abstract Integration of regional seismic reflection data with
swath bathymetry and imagery data and onshore geology has revealed the complex
sequence of tectonic events that have affected the development of the offshore
Fiordland margin. There are no core or dredge samples to constrain the timing
of these events, but comparison with recent work on the Tertiary evolution of
the Australia-Pacific plate margin provided a temporal framework for the
subsurface interpretation. The integrated dataset allows the prediction of the
age and likely lithology of the seismic sequences, the timing of tectonic
events, and details of how structures along the Fiordland plate margin
developed in response to changes in relative plate motion direction.
We conclude that Cretaceous rifting in the Tasman Sea formed half-grabens
along Caswell High and beneath the Fiordland Basin. Up to several kilometres of
Cretaceous to Early Eocene sediments, probably terrestrial and marginal marine
sediments derived from the Campbell Plateau, are preserved in these grabens.
A second phase of rifting in the Eocene, associated with the formation of the
Southeast Tasman Sea, resulted in the separation of the Caswell High and
Fiordland Basin block from the Campbell Plateau and the start of its journey
northwest, northeast, and finally east to its present position adjacent to
Fiordland. The rift sediments are overlain by a relatively uniform sequence,
probably Late Eocene to Mid Miocene deep-water carbonates. Strike-slip faults
developed along the continental shelf and slope in the Miocene, and increasing
margin-normal shortening in the Pliocene-Pleistocene, led to the development of
thrust faults along the margins of sediment lobes in the Fiordland and Milford
Basins. The youngest sediments are up to several kilometres thick, probably
Late Miocene-Quaternary clastics derived from Westland and Fiordland.
Keywords sedimentation; stratigraphy; structure; Fiordland;
New Zealand; plate tectonics
New Zealand Journal of Geology & Geophysics, 2000, Vol. 43:
289-302
0028-8306/00/4302-0289 $7.00/0 (c) The Royal Society of New Zealand
2000
PDF file of entire paper: medium quality (6172K); (scanned from paper original: notes about this process)
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