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Journal of the Royal Society of New Zealand abstracts
Integrated outcrop, drill core, borehole and seismic stratigraphic architecture of a cyclothemic, shallow-marine depositional system, Wanganui Basin, New Zealand
T. R. Naish1, B. D. Field1, H. Zhu1, A. Melhuish1, R. M. Carter2, S. T. Abbott3, S. Edwards2, B. V. Alloway1, G. S. Wilson4, F. Niessen5, A. Barker6, G. H Browne1, and G. Maslen1
1Institute of Geological and
Nuclear Sciences, P.O. Box 30 368, Lower Hutt, New Zealand.
Email: t.naish@gns.cri.nz
2Marine Geophysical Laboratory,
James Cook University, Townsville, Queensland 4811, Australia.
3School of
Environmental Science and Management, Southern Cross University, P.O.
Box 157, East Lismore, NSW, 2480, Australia.
4Department
of Geology, University of Otago, P.O. Box 56, Dunedin, New Zealand.
5Alfred-Wegener-Institute
for Polar and Marine Research, P.O. Box 120161, D-27515
Bremerhaven, Germany.
6Department
of Earth Sciences, Parks Road, Oxford OX1 3PR, United Kingdom.
Abstract Late Pliocene to mid-Pleistocene (c. 2.1–0.4 Ma) strata exposed in the, now classical, Nukumaru and Castlecliff coastal cliff sections north-west of Wanganui comprise 25, 6th (41 ka) order and 5th (100 ka) order, shallow-marine to marginal marine stratigraphic sequences, deposited during global glacio-eustatic sea-level cycles corresponding to Marine Isotope Stages (MIS) 78–10. Here, we characterise the sequences using: (1) a series of drill cores sited above and behind the coastal outcrops, which recovered a composite record of c. 450 m, (2) a new high resolution multichannel seismic reflection profile acquired along the beach adjacent to the coastal cliffs, and (3) downhole digital logs from the boreholes. This paper integrates the outcrop and subsurface datasets to produce a high resolution model of the stratigraphic signatures and 2D architecture of a cyclical, shallow-marine deposition system. Such models have significant applications to petroleum exploration, and enable the distribution of reservoir facies and intervening seal rocks within sequences, together with the nature of the connectivity of sandstone facies between sequences, to be evaluated. Similar hydrocarbon-producing systems within the Eocene Kapuni Group (e.g., Mangahewa and Kaimiro formations) have been, and are still, the focus of intense exploration in Taranaki Basin.
Keywords sequence statigraphy; Wanganui Basin; Pliocene-Pleistocene; shallow-marine; cyclothem; seismic reflection; borehole; drillcore
R05007 Received 17 April 2005; accepted 31 May 2005; Online
publication date 27 July 2005
Journal of the Royal Society of New Zealand
Volume 35, Numbers 1 & 2, March/June, 2005, pp 91–122
PDF file of entire paper: Print-quality (28743K) | screen-quality (2472K)
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