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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 54 (1970)

Issue: 3. (March)

First Page: 558

Last Page: 558

Title: Benthic Foraminiferal Trends in Pacific-Antarctic Basin: ABSTRACT

Author(s): Fritz Theyer

Article Type: Meeting abstract


Trawl samples collected in depths from 3,000 to more than 5,000 m allow the following conclusions.

1. The fauna consists mainly of large, widely distributed bathyal and abyssal Foraminifera. Most assemblages are more than 85% arenaceous, but between 3,000 and 4,000 m some assemblages are predominantly calcareous.

2. Species diversity, although variable, reaches a maximum of 37 at nearly 4,300 m. This maximum coincides with a peak in a diversity factor based on information theory; species equitability is highest at a slightly shallower level. Areal diversity trends are absent.

3. Eleven species are dominant both in abundance and consistency of appearance. Of these, only Uvigerina peregrina disrupta Todd is calcareous. Hormosina robusta (Pearcy) is the most characteristic species in the area. Other important forms are Haplophragmoides umbilicatus Pearcy, Cyclammina pusilla Brady, and Recurvoides contortus Earland. Cyclammina orbicularis Brady dominates the shallowest station (3,043 m), and Reophax nodulosus Brady is dominant at the deepest station (5,124 m).

4. Latitudinal and longitudinal transects indicate that Cyclammina pusilla and Haplophragmoides umbilicatus increase in relative abundance toward the south, Reophax spp. and H. umbilicatus increase toward the east, and Psammosphaera fusca Schulze increases toward the west.

5. On the basis of quantitative data available from the western Southern Ocean, a generalized benthic Antarctic foraminiferal zonation seems possible. Bathymetric plots of cumulative percentages of selected index species help in achieving such a zonation.

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Copyright 1997 American Association of Petroleum Geologists