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The AAPG/Datapages Combined Publications Database

CSPG Bulletin


Bulletin of Canadian Petroleum Geology
Vol. 18 (1970), No. 4. (December), Pages 474-492

Allochthonous Reef-Debris Limestone Turbidites Powell Creek, Northwest Territories

W. S. MacKenzie


Carbonate strata of the Middle Devonian Ramparts Formation outcrop in the vicinity of Powell Creek, about 50 mi west-northwest of Norman Wells in the Northwest Territories. These sediments, about 100 ft thick and composed mainly of lime muds at Powell Creek, increase to about 800 ft in thickness a short distance to the west and are present in a "reefal"3 facies with corals and stromatoporoids. At Powell Creek about 53 ft of allochthonous beds consisting of argillaceous limestones and calcareous shales, the "unnamed beds" of Braun (1966), overlie reefmargin carbonates of the Ramparts Formation. Large blocks of coral- and stromatoporoid-bearing limestone occur within thin-bedded argillaceous carbonates in the lower part of the unit, and graded echinoderm beds occur among the overlying calcareous shales. The limestone blocks are allochthonous debris derived from the nearby carbonate bank. The graded echinoderm beds were deposited by turbidity currents which, from time to time, swept skeletal remains from relatively shallow water near the carbonate bank into deeper water where shales were accumulating.

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