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The Devonian Carbonate-Clastic Sequence on Southwest Ellesmere Island, Arctic Canada
Measurements of numerous stratigraphic sections, coupled with published information, indicate that the Devonian Blue Fiord and Bird Fiord formations are a prograding carbonate sequence which grades upward into the silici-clastics of the Okse Bay Group.
The Blue Fiord Formation in the type area exhibits the following succession of lithofacies upwards in the stratigraphic column: (a) carbonate buildups, rich in Alveolites and other corals, isolated in the Hazen Trough, with associated brachiopod-rich (Gypidula-Atrypa-Schizophoria biofacies) limestones; (b) deep and/or quiet water, poorly fossiliferous, black shales, and lime-mudstone of the “back-reef” basin (connected with Hazen Trough), with associated calciturbidite beds; and (c) platform and platform margin coral wackestones and crinoidal grainstones.
Conformably overlying the Blue Fiord Formation is the Bird Fiord Formation, which is composed of limestones with coral-rich beds, and calcareous shales, probably deposited on, or at the edge of, a carbonate platform. At the top of this formation are interbedded shales, limestones, and sandstones deposited in a deltaic environment.
The succession ended with Middle Devonian deltaic siltstone, sandstone, and shale of the lower Okse Bay Group overlain by alternating sandstones and shales of fluvial origin. This marked the end of deposition in the Franklinian Basin.
Progradation started in the Early Devonian, probably caused by a decrease in the rate of subsidence and/or an increased rate of carbonate sedimentation. By Middle Devonian time, relative uplift had taken place, and a land area was supplying the clastic sediments of the Bird Fiord Formation, and the Okse Bay Group.
The inferred distribution of the facies in Early and Middle Devonian time implies a direction of progradation towards the north and west from a land area situated in northern Devon Island and eastern Ellesmere Island. In the late Middle and Late Devonian, the composition of clastic strata and paleocurrent data from fluvial sediments suggest a source east of the basin (eastern part of Canadian Shield, or western Greenland Shield).
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