New Zealand Journal of Geology and Geophysics abstracts
Allostratigraphy of coastal south and east Otago: a stratigraphic framework for
interpretation of the Great South Basin, New Zealand
S. G. McMILLAN
Institute of Geological & Nuclear Sciences
Private Bag 1930
Dunedin, New Zealand
G. J. WILSON
Institute of Geological & Nuclear Sciences
P.O. Box 30368
Lower Hutt, New Zealand
Abstract Sixteen unconformities, some with correlative
conformities, are recognised within the Late Cretaceous-Tertiary
transgressive-regressive sediments of coastal Otago. These provide the basis
for stratigraphic division and correlation with seismic reflectors in the
offshore age-equivalent sediments of the Great South Basin. The ages of the
unconformities/conformities are constrained mainly by dinoflagellate
biostratigraphy, but foraminiferal biostratigraphy is important for the
Oligocene-Miocene. In terms of current biozone-stage correlation, the 16
unconformities comprise the following: two intra-Haumurian (Late Cretaceous)
unconformities, one at the K/T boundary, three intra-Teurian (Paleocene)
unconformities, two of early Waipawan age, two of late Mangaorapan - early
Heretaungan age, a late Heretaungan unconformity, a late Porangan - early
Bortonian unconformity, a late Bortonian unconformity (a total of seven Eocene
unconformities), a late Runangan - early Whaingaroan unconformity, a late
Whaingaroan unconformity (both Oligocene), and a mid-Waitakian (Miocene)
unconformity. Other, early-mid-Cretaceous unconformities are inferred from
offshore seismic profiles. Six unconformities/correlative conformities in
onland Otago provide the basis for recognising four informal alloformations.
Keywords allostratigraphy; Cretaceous-Cenozoic;
unconformities; Great South Basin (GSB); Otago
New Zealand Journal of Geology and Geophysics, 1997, Vol. 40: 91-107
0028-8306/97/4001--0091 $2.50/0 (c) The Royal Society of New Zealand
1997
PDF file of entire paper: medium quality (2663K); (scanned from paper original: notes about this process)
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