Sedimentation and Paleoecology of the Devonian Escuminac Formation and Related Strata, Escuminac Bay, Quebec
D. L. Dineley, B. P. J. Williams, 1968. "Sedimentation and Paleoecology of the Devonian Escuminac Formation and Related Strata, Escuminac Bay, Quebec", Late Paleozoic and Mesozoic Continental Sedimentation, Northeastern North America, George deVries Klein
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In a revision of Devonian stratigraphy in the Escuminac Bay area, Quebec, Canada, the Escuminac and Fleurant Formations are retained within the Upper Devonian; the Pirate Cove Formation is regarded as Lower or Middle Devonian, which is based on its conformity with the underlying beds of known Lower or Middle Devonian age and because it is unconformably overlain by the Fleurant.
The Escuminac, Fleurant, and Pirate Cove sediments were deposited in a complex of alluvial fans, flood plains, river channels, and lakes. The Pirate Cove Formation contains angular limestone-clast “fanglomerates,” channeled and ripple-bedded sandstones and shales, and is transitional into the underlying “Gaspé Sandstones.” In contrast, the Fleurant Formation is exclusively a mixed roundstone conglomerate clearly indicative of fluvial origin and intimately associated with the overlying Escuminac fish-bearing beds.
The Escuminac Formation contains several shale members separated by a number of sandstone-shale units. Both “varved” and pyritiferous horizons are recognized. Environmental interpretation of this formation, based on fossils, lithologies, and primary sedimentary structures, suggests a fresh- to brackish-water lacustrine regime in which sand-laden density underflows periodically occurred. These turbid currents had a locally profound effect on the benthonic fish fauna of the lake. Throughout Escuminac time a unimodal current pattern from east to west was maintained. Some attempt is made to fit these local paleoenvironments into a regional picture of Devonian continental sedimentation.