Sedimentology and Provenance of the Norton Basin, offshore Alaska: Insight into the Paleogene Evolution of the Paleo-Yukon Drainage System
Abstract/Contents
- Abstract
- The onset of flat-slab subduction across the southern Alaskan margin has been linked to documented variations in exhumation, magmatism, basin formation and structural styles. While previous outcrop-based studies have focused on understanding the latter stages of basinal responses to these tectonically induced forces, there remains limited knowledge of the response of large paleo-drainage systems. This study provides new insight into the drainage response of tectonic reorganization by investigating the Cenozoic stratigraphic record of the Norton Basin, a subsurface basin lying ~ 53 kilometers offshore from the modern Yukon delta. Stratigraphic analyses of subsurface core was coupled with new U-Pb grain ages to understand depositional and provenance changes across lower Eocene to upper Oligocene basinal stratigraphy. Eocene stratigraphy preserves a regional upper mid-Eocene unconformity that separates lower Eocene volcaniclastic strata from upper Eocene fluvial and deltaic strata deposited by the early paleo-Yukon drainage. Oligocene stratigraphy documents a progressive drainage expansion of the established paleo-Yukon in response to the onset and expansion of flat-slab subduction across the southern Alaskan margin. U-Pb detrital zircon provenance analysis along with new maximum depositional age constraints support a mid-Oligocene age (25-31 Ma) for the initial collision of the Yakutat microplate. Appearance of early Cretaceous, Jurassic, and Triassic grain ages within the Norton Basin support a southeastward expansion of the paleo- Yukon to the then exhuming, Chugach Mountains and Wrangellia Composite Terrane. As the Yakutat microplate subducted inboard as a coupled flat slab, uplift and denudation of the Alaska Range commenced. Within the Norton Basin, Cenozoic grain ages derived from the Alaska Range appear and increase in abundance between the mid- and late Oligocene, indicating the continual expansion of the paleo-Yukon drainage in response to the inboard progression of the flat slab and corresponding uplift. The stratigraphic record of the Norton Basin provides a rare record of the continual deformational effects of flat slab subduction from the initial collision linked to the subduction of thick oceanic plateau crust beneath the southeastern Alaskan margin to the development of flat slab subduction across the southern Alaska throughout the mid to late Oligocene. Results from this study demonstrate the utility of the offshore detrital record in unraveling the topographic and tectonic evolution of areas comprising extensively deformed and poorly exposed onshore terranes.
Description
| Type of resource | text |
|---|---|
| Date created | December 2020 |
Creators/Contributors
| Author | White, Colin James |
|---|---|
| Primary advisor | Graham, Stephan |
| Advisor | Malkowski, Matthew |
| Degree granting institution | Stanford University, Department of Geological Sciences |
Subjects
| Subject | Geological Sciences |
|---|---|
| Subject | School of Earth Energy & Environmental Sciences |
| Genre | Thesis |
Bibliographic information
Access conditions
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
Preferred citation
- Preferred Citation
- White, Colin James. (2020). Sedimentology and Provenance of the Norton Basin, offshore Alaska: Insight into the Paleogene Evolution of the Paleo-Yukon Drainage System. Stanford Digital Repository. Available at: https://purl.stanford.edu/wf655fw0220
Collection
Master's Theses, Doerr School of Sustainability
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- Contact
- cjw2934@stanford.edu
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