T33D-2958
Margin Architecture and Sediment Flux as Controls on Submarine Fan Development: Tectonic-Climate Interactions in the Gulf of Alaska
Wednesday, 16 December 2015
Poster Hall (Moscone South)
Sean P S Gulick1, Aleksandr Montelli1, John Marshall Swartz2, Susannah Morey1, John M Jaeger3, Alan C Mix4, Robert Reece5, Kittipong Somchat6, Patrick Ford Wagner6 and Lindsay Lowe Worthington7, (1)University of Texas at Austin, Austin, TX, United States, (2)Institute for Geophysics, Austin, TX, United States, (3)University of Florida, Ft Walton Beach, FL, United States, (4)Oregon State University, Corvallis, OR, United States, (5)Texas A&M University, College Station, TX, United States, (6)Texas A & M University College Station, College Station, TX, United States, (7)University of New Mexico Main Campus, Albuquerque, NM, United States
Abstract:
The oblique collision of the Yakutat microplate into southeast Alaska generates the St. Elias Mountains, a coastal orogen with significant moisture from the Gulf of Alaska resulting in large, temperate glacial systems that expand to and eventually cross the continental shelf during glacial maxima. We present an overview of the evolution of sediment routing on this margin from integration of seismic images, updated age models and core-log-seismic correlations from IODP Expedition 341 drilling sites, and mapping efforts from shelf, slope, and fan. We focus on the three dominant glacial systems during the climatically important intensification of Northern Hemisphere glaciation at the Plio-Pleistocene transition and the further intensification of glaciation since the mid-Pleistocene transition. Along strike, sediment delivery to deepwater from the three glacial systems varied according to Pleistocene shelf accommodation space. The Alsek crossed a narrower shelf with a bedrock high near the shelf edge; the Malaspina-Hubbard system crossed an undeformed, ~1 km deep shelf; the Bering-Bagley system crossed a several km deep shelf deforming as an active fold and thrust belt. The Malaspina and Bering catchments exhibit high exhumation rates onshore due to the Yakutat collision and upon reaching the shelf edge these glaciers generate trough mouth fans (TMFs) on the adjacent continental slope but only after first filling the available accommodation with glacigenic sediment and lowering the slope gradient through progradation. The Alsek crosses the shelf earliest but never with sufficient sediment flux to generate a TMF. An east-west transition in adjacent deepwater submarine channels that feed and generate the Surveyor Fan suggests that shelf accommodation and sediment flux are primary controls on sediment routing from orogen to submarine fan. Both of these parameters are in turn a function of initial tectonic architecture and ongoing orogen dynamics.
