Geophysical Characterization of the Central Yakutat Shelf and Cenozoic Basin Development, Offshore Southeastern Alaska

• Main Author: Price, Rachel
• Format: Text
• Language: English
• Published: UNM Digital Repository 2016
• Subjects: Geophysics; Alaska; Yakutat; basin development; Gulf of Alaska; glacier
• Online Access: https://digitalrepository.unm.edu/eps_etds/107; https://digitalrepository.unm.edu/cgi/viewcontent.cgi?article=1107&context=eps_etds

In southeastern Alaska, the collision of the Yakutat microplate with North America has led to uplift of the highest costal mountain range in the world, the Chugach and St. Elias Mountains. Once uplift of the ranges produced sufficient topography to intercept precipitation sourced from the Gulf of Alaska, glaciation on the margin was initiated. The margin now presents a unique area to study the interactions between tectonics and climate driven processes. The area of maximum uplift and exhumation is termed the southeastern Alaskan syntaxis, and is characterized by complicated patterns of deformation and sedimentation in an offshore basin. This study presents a two dimensional compressional velocity model that helps to constrain patterns of deformation offshore of the syntaxis. The velocity model is also interpreted in conjunction with a coincident seismic reflection line in order to characterize Cenozoic sediment packages at depth and better understand the evolution of a tectonically active glaciated margin. The study is able to constrain the front of lateral compaction due to porosity loss to a narrow band between the Malaspina Fault and Yakutat Bay, as well as the offshore location of the pinch out of the Poul Creek Formation. Interpretation of the seismic reflection line reveals transitions in sediment depositional processes, depocenters, and sources in the central Yakutat shelf over time, particularly the transition to the Malaspina Glacier as the major sediment source in the area.