New Zealand Journal of Geology and Geophysics abstracts
Basement geology of Taranaki and Wanganui Basins, New Zealand
N. MORTIMER
A. J. TULLOCH
Institute of Geological & Nuclear Sciences
Private Bag 1930
Dunedin, New Zealand
T. R. IRELAND
Research School of Earth Sciences
Australian National University
Canberra ACT 0200, Australia
Abstract We present a revised interpretation of the basement
geology beneath Late Cretaceous to Cenozoic Taranaki and Wanganui Basins of
central New Zealand, based on new petrographic, geochemical, and
geochronological data from 30 oil exploration wells. Recently published
structural and magnetic interpretations of the area assist in the interpolation
and extrapolation of geological boundaries. Torlesse and Waipapa Terranes have
been identified in Wanganui Basin, and Murihiku Terrane in eastern Taranaki
Basin, but Maitai and Brook Street Terrane rocks have not been recognised.
Separation Point Suite, Karamea Suite, and Median Tectonic Zone igneous rocks
are all identified on the basis of characteristic petrography, geochemistry,
and/or age. SHRIMP U-Pb zircon measurements on igneous samples from western
Taranaki wells do not give precise ages but do provide useful constraints:
Motueka-1 granite is latest Devonian - earliest Carboniferous; Tangaroa-1 and
Toropuihi-1 are Carboniferous; and Surville-1 is Cretaceous (cf. Separation
Point Suite). Our interpretation of sub-basin geology is compatible with
previously observed onland relationships in the North and South Islands.
Keywords North Island; Taranaki; Wanganui; Eastern Province;
Western Province; Median Tectonic Zone; terranes; granitoids; petrology;
petrography; geochemistry; U-Pb dating; zircon
New Zealand Journal of Geology and Geophysics, 1997, Vol. 40: 223-236
0028-8306/97/4002-0223 $7.00/0 (c) The Royal Society of New Zealand
1997
PDF file of entire paper: medium quality (1470K); (scanned from paper original: notes about this process)
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