The Stratigraphy and sedimentology of siliciclastic rocks, west-central Yukon, and their tectonic implications
Abstract
Siliciclastic strata between Carmacks and Dawson in west-central Yukon were previously interpreted as Eocene or younger in age and fluvial/continental in origin. Detailed stratigraphic and sedimentologic investigations in the Indian River and Sixtyrnile River areas indicate that some of the strata are much older and were deposited in a paralic environment. The Indian River Formation (new) is at least 500 m thick and consists of interbedded sandstone, shale, conglomerate dinoflagellates and minor indicate coal. that the Spores, formation pollen and is Middle Albian in age and was deposited in a hitherto unrecognized marginal marine basin by a southward prograding fan-delta complex. The Sixtyrnile Formation (new) is approximately 200 m thick and consists of interbedded conglomerate, sandstone, shale and minor limestone and tuff, and intercalated basalt flows. the close association of Palynomorphs, fossil leaves and volcanic rocks indicate the formation is Late Cretaceous-Paleocene in age, possibly Maastrichtian, and is assigned to the lower part of the Carmacks Group. The formation was deposited in a restricted, nonmarine basin by a northward flowing braided-meandering river system and a southward prograding alluvial fan complex. Previous paleogeographic reconstructions indicate that Whitehorse Trough, a Late Triassic to Middle Jurassic backarc or forearc basin {Lewes River and Laberge groups, basalt flows, carbonate reefs and flysch), evolved into a series of restricted, nonmarine basins by Late Jurassic to Early Cretaceous time {Tantalus Formation, alluvial plain). This study proposes that the Trough evolved from a Late Triassic to Middle Jurassic backarc or forearc basin into a successor basin by Late Jurassic to Early Cretaceous time {Tantalus and Indian River formations), which subsequently evolved into a series of restricted, nonmarine basins by Late Cretaceous to Paleogene time {Sixtymile Formation and unnamed strata). Late Mesozoic-Paleogene siliciclastic strata in west-central Yukon reflect the collision, suturing and emplacement of allochthonous with autochthonous terranes and are interpreted as part of the "successor basin" molasse facies of the Canadian Cordillera.
Description
Bibliography: p. 311-329.
Keywords
Citation
Lowey, G. W. (1984). The Stratigraphy and sedimentology of siliciclastic rocks, west-central Yukon, and their tectonic implications (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/14715