Sedimentation and Erosion on an Arctic Continental Shelf: Harrison Bay and Colville River Delta, Alaska

• Main Author: Heath, Adrian D. J.
• Other Authors: Eidam, Emily F., Walczak, Maureen H., Kleber, Markus, Stoner, Joseph S., College of Earth, Ocean, and Atmospheric Sciences
• Format: Master Thesis
• Language: English; unknown
• Published: Oregon State University
• Subjects: Sea ice; Alaska
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/4m90f4834

Arctic continental shelves, such as the Alaskan Beaufort Shelf, serve as repositories and active transition zones for terrigenous sediments in the Arctic. A balance of wave energy, sea ice coverage, and sediment delivery primarily from coastline erosion influences arctic continental shelf morphology. Recent reductions in arctic sea ice extent have led to increases in wave energy and shoreline erosion, changing the sedimentation conditions and shelf morphology. Current knowledge of sediment depositional centers and shelf morphology is sparse yet essential for predicting the evolution of continental shelves and shorelines in the Arctic. To investigate this, an observational study in Harrison Bay, AK, was conducted using Pb-210 dating in sediment cores and bathymetric survey comparisons to discern locations of sediment deposition and shelf morphology. Meter-scale bathymetric deepening displays seabed erosion across the inner shelf, including the subaqueous Colville River Delta. Despite seabed erosion dissipating in the middle shelf, a general lack of excess Pb-210 activities in sediment cores indicates modern sediment accumulation is not occurring. Therefore, sediment may be bypassing the middle shelf as the inner shelf profile translates landward with the retreating shoreline. These findings help provide insight into climate-driven changes to sediment deposition and morphological processes on an arctic continental shelf.