New Zealand Journal of Geology and Geophysics abstracts
An integrated biostratigraphy and seismic stratigraphy for the late
Neogene continental margin succession in northern Taranaki Basin, New
Zealand
Rochelle J. Hansen
Peter J. J. Kamp
Department of Earth Sciences
The University of Waikato
Private Bag 3105
Hamilton 2001, New Zealand
Abstract Our aim has been to develop an integrated
biostratigraphy and seismic stratigraphy for the Pliocene and
Pleistocene formations (Ariki, Mangaa, Giant Foresets) in northern
Taranaki Basin to better understand the evolution of the modern
continental margin offshore central-western North Island, New Zealand.
Detailed mapping of seismic reflectors in part of the basin, when
compared with correlations of late Neogene stage boundaries between 11
well sections, has highlighted crossover between the datasets. To help
resolve this issue, the biostratigraphy of the Pliocene-Pleistocene
parts of each of four well sections (Arawa-1, Ariki-1, Kora-1, and
Wainui-1) has been re-examined using a dense suite of samples. In
addition, the biostratigraphy of seven other well sections (Awatea-1,
Kahawai-1, Mangaa-1, Taimana-1, Tangaroa-1, Te Kumi-1, and Turi-1) has
been re-evaluated. The crossover is partly attributed to a combination
of sampling resolution inherent in exploration well sections, the mixed
nature of cuttings samples, and the general scarcity of age-diagnostic
planktic foraminifera in the late Neogene formations. The achievement
of seismic closure suggests that error in the mapping of the seismic
reflectors is not a significant source of the uncertainty (crossover).
We have developed a workable time-stratigraphic framework by
qualitatively weighting the biostratigraphic data in each of the well
sections, thereby identifying the parts of particular well sections
with the highest resolution microfossil data and the optimal
stratigraphic position of stage boundaries with respect to the mapped
seismic horizons/seismic units. Hence, it is possible to assign the
known numerical ages for these stage boundaries to reflection
horizons/seismic units mapped within the basin. We have applied this
information to produce a series of isopach maps for successive stage
boundaries that help show the sedimentary evolution of the continental
margin succession west of central North Island.
Keywords Ariki Formation; Mangaa Formation; Giant
Foresets Formation; biostratigraphy; chronostratigraphy; seismic
correlation; Taranaki Basin
G04043; Received 9 November 2004; accepted 16 September 2005; Online
publication date 28 February 2006
New Zealand Journal of Geology & Geophysics, 2006, Vol. 49:
39–56
0028–8306/06/4901–0039 © The Royal Society of New Zealand 2006
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