Sediment transport processes in the Gulf of Alaska: a morphological analysis of channel and fan sedimentary features

The Alaskan Abyssal Plain is home to three active channel/fan systems: the Surveyor, Chirikov, and Baranof systems. Individual studies of the Surveyor and Baranof fans indicate that these systems derive their sediments from the glacially dominated Northeast Pacific North American coast. The Pleistocene aged sediments found in the Surveyor Fan record some of the highest sediment accumulation rates (up to 130 cm/kyr) ever documented and show that this system is one of the youngest recognized large submarine fans. Further, the Surveyor and Baranof systems are two of the largest submarine fans in the world and their development has been significantly influenced by climatic and tectonic forcing. Specifically, these fans either developed or expanded with increased glacial activity in the Pleistocene that resulted in increased sediment flux to the Gulf of Alaska. While this influence is widely accepted, the depositional processes within the modern and past systems are poorly understood. A thorough investigation of these deep ocean sediment transport processes can further inform our understanding of this high-latitude source-to-sink system. Although the existence of multiple fans on a margin isn't exclusive to Alaska, the slope of the Gulf's basin floor indicates a relatively unique condition. As channels in the Gulf of Alaska carry sediment away from the continental slope margin—parallel to the Aleutian Trench—the basin floor between the adjacent channels generally slopes towards the Aleutian Trench. The presence of large scale bedforms on this sloped surface indicate the potential for significant sediment remobilization on the basin floor between active channels. Additionally, these systems are characterized by higher relief western channel banks and varying states of equilibrium, as well as differing degrees of sinuosity and channel width/depth. We intend to quantify these and other morphological features in the Gulf of Alaska with the goal of investigating active and ancient sediment transport mechanisms and the probable interaction of multiple channel/fan systems on an actively subducting plate.