Continental marine transition in the Devonian of Prince of Wales Island, Northwest Territories

Abstract

In eastern Prince of Wales Island the Peel Sound Formation is subdivided into upper and lower members on the basis of lithology. The upper member comprises five laterally equivalent north–south facies belts which are in westward order:1) Conglomerate Facies: cobble and boulder conglomerates deposited on alluvial fans mainly by the action of debris floods.2) Conglomerate–Sandstone Facies: interbedded conglomerate, fine to coarse red sandstone and red siltstone in a repeated fining-upward succession, deposited by low sinuosity braided streams. Cyclic sedimentation is attributed to channel migration and infill.3) Sandstone Facies: the presence of laterally extensive planar cross sets suggests point bar deposition in high sinuosity streams. Tabular bedded sandstone was deposited by stream floods in upper regime flow.4) Sandstone–Carbonate Facies: streams flowing westward formed small deltas, accumulating red, pink, and buff sandstones as topset deposits, interbedded with dolomites containing marine fossils, and clean washed gray sandstones, shales and dolomites with ostracods, pelecypods, gastropods, and Lingula, indicating an estuarine environment.5) Carbonate Facies: dolomites with abundant marine fauna and limited clastic content. Sedimentary structures indicate quiet, shallow water conditions.Paleocurrent evidence indicates an easterly source, confirmed by conglomerate clasts derived from the Boothia Uplift, an area of Lower Paleozoic and Proterozoic rocks extending northwards from the Boothia Peninsula to Somerset Island.