Yukon River: Evidence for Extensive Migration during the Holocene Transgression.

Area of Science:

• Geology
• Quaternary Science
• Oceanography

Background:

• The Yukon River's historical course is crucial for understanding Bering Sea paleogeography.
• Holocene sea-level changes significantly impacted coastal river systems and sediment deposition.

Purpose of the Study:

• To reconstruct the paleochannel of the Yukon River during the Holocene sea-level transgression.
• To identify the factors controlling the river's northward migration across the Bering Sea continental shelf.

Main Methods:

• Analysis of seismic reflection data to identify subbottom structures and remanent channels.
• Sediment core analysis to determine sediment composition and accumulation rates.
• Geological mapping of the east-central Bering Sea continental shelf.

Main Results:

• Evidence of a major river system south of Nunivak Island during the Wisconsin maximum.
• Identification of distinct subbottom structures and deltaic sediments indicating northward river migration.
• Anomalous sediment accumulation rates on the shelf, consistent with a large riverine input.

Conclusions:

• The Yukon River migrated over 300 km northward during the Holocene, establishing its present course.
• River migration was driven by Holocene sea-level transgression and influenced by shelf topography.
• These findings provide insights into Quaternary landscape evolution in the Bering Sea region.