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Abstract

There is a profound change in sedimentary environment and in fauna going from
the Middle-Upper Ordovician of Ida Bay to Surprise Bay over a present distance
of only 25 km. The transition is from peritidal carbonates at Ida Bay, to subtidal
carbonates at Precipitous Bluff to deep subtidal calcareous shales at Pt. Cecil to
deep water micrites, graptolitic shales and carbonate turbidites at Surprise Bay.
The blind (Nanshanaspis, Bulbaspis) or large eyed (Telephina) trilobites at Surprise
Bay suggest sub-photic or twilight depositional conditions and a phosphatic,
ironstone hardground enriched in metals and with imploded nautiloids suggests
a zone of nutrient-rich upwelling currents at about 300 ± 50 m water
depth. Macrofauna from Ida Bay is mainly endemic and is associated with Midcontinent
province type or endemic conodonts. The shelf edge sections at Precipitous
Bluff and Pt. Cecil contain more widespread macrofossils and Midcontinent
conodonts whereas the macrofauna from the deep-water deposits is
widespread or cosmopolitan and is associated with North Atlantic province
conodonts.

Item Type:	Book Section
Authors/Creators:	Burrett, CF and Stait, B and Sharples, C and Laurie, J
Publisher:	Oslo : Universitetsforlaget [University of Oslo]
Additional Information:	Copyright © 1984 Oslo : Universitetsforlaget [University of Oslo]
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