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The Sedimentology and Petrology of the Okse Bay Group (Middle and Upper Devonian) on S.W. Ellesmere Island and North Kent Island in the Canadian Arctic Archipelago

Randolph James Rice

Abstract

The Strathcona Fiord Formation varies from a paralic environment at Stenkul Fiord to a small, highly sinuous, meandering fluvial environment at Muskox Fiord. The remaining formations in the Okse Bay Group are consistent with respect to their depositional setting. The Nordstrand Point Formation constitutes a small, sinuous, meandering fluvial environment. The Fram and Hell Gate Formations represent progressively larger, less sinuous, meandering fluvial systems. The Hecla Bay Formation is the only braided fluvial formation in the Okse Bay Group.

The Okse Bay Group is extremely compositionally homogeneous, both stratigraphically and areally. As a result of burial metamorphism, most of the originally sub-arkosic sandstones are now quartz arenites. Sandstone in the Okse Bay Group is well sorted and very fine grained. The sand size detritus in most of the Okse Bay Group was well lithified during early diagenesis. The sand of the Hecla Bay Formation was not lithified until late diagenetic conditions were attained. Late diagenetic textures suggest that maximum burial depth varied between 3 - 5.5 km depending on the geothermal gradient.

Cathodoluminescence microscopy revealed mainly rounded detrital textures, minor pressure solution of framework grains, confirmed the cement paragenesis and contributed to the source terrane interpretation.

Variations in the volume of sandstone, characteristic grain size, fluvial architecture, and paleochannel scale in the Okse Bay Group are complimentary in suggesting that continuous but variable rates of epeirogenesis of a source terrane occurred throughout Okse Bay Group time.

Regional paleocurrent trends, areal detrital composition trends and spore-based younging trends all indicate an eastern source terrane.

Source terrane constraints imposed by the interpretation of bedrock composition and tectonic behavior, and the directional constraints, are satisfied by the Ellesmere Island - Greenland craton with its Proterozoic intracratonic Thule Basin. Most of the detritus was recycled from the Thule Basin.