New Zealand Journal of Geology and Geophysics abstracts

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Bryozoan fauna of the Kaipuke Siltstone, northwest Nelson: a Miocene homologue of the modern Tasman Bay coralline bryozoan grounds

DENNIS P. GORDON

New Zealand Oceanographic Institute
National Institute of Water & Atmospheric Research (NIWA)
P.O. Box 14 901, Kilbirnie
Wellington, New Zealand

IAN G. STUART
JOHN D. COLLEN

Department of Geology
Research School of Earth Sciences
Victoria University of Wellington
P.O. Box 600
Wellington, New Zealand

Abstract  The Kaipuke Siltstone Formation (Westhaven Group) near the Anatori River mouth, northwest Nelson, contains a reasonably well preserved bryozoan fauna of Otaian age. Analysis of this fauna has yielded six species of Cheilostomatida, mostly with an erect-rigid colony form. One new species, Hippoporina miocenica, is described. Four of the species appear conspecific with modern bryozoans, including the two species (Celleporaria agglutinans (Hutton) and Hippomenella vellicata (Hutton)) that dominate the modern Tasman Bay bryozoan grounds. From foraminiferal evidence and from what is known of the ecological requirements of the modern bryozoan species it is possible to infer the paleoenvironment of the Kaipuke Siltstone fauna, viz, an area of near-oceanic salinity, water movements able to exceed 0.3 m/s, a seasonal temperature range probably c. 12.5-17deg.C, and with the possibility of terrigenous sediment accumulation. We conclude that this fauna is an early Miocene homologue of the present-day, ecologically important "Tasman Bay coral" and that this biotope has persisted for at least 20-22 Ma.

Keywords  Kaipuke Siltstone; northwest Nelson; Otaian; Altonian; Miocene; Bryozoa; "Tasman Bay coral"; paleoenvironment; Celleporaria; Hippomenella; Hippoporina n. sp.

New Zealand Journal of Geology and Geophysics, 1994, Vol. 37: 239-247

0028-8306/94/3703-0239 $2.50/0 (c) The Royal Society of New Zealand 1994

PDF file of entire paper: medium quality (3945K); (scanned from paper original: notes about this process)

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