Stratigraphy, sedimentology and chronology of the Eagle River meltwater channel and braid delta, northern Yukon.

摘要

The Eagle River meltwater channel and braid delta record overflow from the Bonnet Plume Basin caused by the achievement of the maximum position of the northwest Laurentide Ice Sheet in the late Pleistocene. This thesis examines landforms and deposits associated with spillway drainage along the Eagle River and subsequent fine-grained deposition in the Bell Basin. A process-depositional model for flood channel evolution was applied successfully to predict and characterize erosional and depositional features related to sudden, short-lived, high-energy flooding along the Eagle River. Braid delta sedimentation within the meltwater channel is crudely-coarsening upward and contains no evidence for a significant hiatus in deposition. Radiocarbon ages obtained on macrofossils with 'steppe-tundra' ecological affinity indicate an age of ca. 15-16,000 14C BP for the landform. The high frequency of non-finite and mixed ages underscores the significant problem of reworked, well-preserved macrofossils in Arctic environments.