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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 64 (1980)

Issue: 5. (May)

First Page: 793

Last Page: 793

Title: Early Paleozoic Conodont Biostratigraphy and Paleogeography of Northwestern Canada: ABSTRACT

Author(s): R. S. Tipnis, M. P. Cecile

Article Type: Meeting abstract

Abstract:

Early Paleozoic rocks in northwestern Canada were deposited on a broad Atlantic type shelf and include platform carbonate rocks and transitional and basinal facies that range in composition from calcilutites to cherts. The Paleozoic history of northwestern Canada began with widespread deposition of Lower Cambrian quartzite and carbonate. In the Middle and early Late Cambrian, shales were deposited in deep troughs and continental areas separated by tectonic arches. During the latest Cambrian and Early Ordovician, platform carbonates were deposited on a broad shelf adjacent to a belt of deep water limestone. Middle Ordovician time was characterized by uplift to the north; carbonate deposition changed abruptly basinward into graptolite shales to the south. Late Ordovician-Ea ly Silurian carbonate deposition on the platform graded basinward into shales and limestones.

The phosphatic microfossil Mellopegma occurs in Lower to Middle Cambrian basinal strata while conodonts of the Late Cambrian Proconodontus Zone are common to both the platform and the basinal strata. A nearly continuous sequence of Early to Middle Ordovician conodont faunas is found in the platform carbonate rocks. These Mid-Continent type faunas include the Early Ordovician faunas A to E of Ethington and Clark and the Middle Ordovician faunas 1 to 9 of Sweet, Ethington, and Barnes. Coeval basinal and transitional facies of Early and Middle Ordovician age are characterized by North Atlantic type conodonts and a few Mid-Continent forms that sharply decline numerically toward the basin. Late Ordovician conodonts are poorly represented in the platform facies; spot samples from transition l and basinal facies yield predominantly North Atlantic taxa.

Lateral and temporal distribution of conodont faunas from northwestern Canada closely resemble those of coeval faunas reported from the Ibex area of western Utah.

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