Date of Award

Summer 2025

Document Type

Open Access Thesis

Department

Geography

First Advisor

Andrew Leier

Abstract

Sediment, runoff, and nutrient input to the Arctic Ocean plays a critical role in both physical and biological processes that impact regional and global systems. The Beaufort-Mackenzie Basin, situated in the Arctic Ocean offshore northwestern Canada, contains more than 14 km of clastic strata and provides a record of erosion and sediment transport from the Cretaceous to present. Pliocene sedimentation rates within the basin jump nearly 2000% relative to underlying units, but the cause of this shift remains unknown. We used cuttings from the N. Issungnak L-86 well, focusing on the Oligocene-lower Miocene Kugmallit and Mackenzie Bay sequences and the Pliocene-Pleistocene Iperk sequence for U-Pb geochronology analysis. Overall, these units have consistent zircon populations with peaks at roughly 100, 400, 1200-1800, and 2700 Ma, indicating a relatively consistent sediment provenance between Oligocene and Pleistocene time. Based on the similarities between populations in our samples and those in the Northern Cordillera of Canada, we interpret that sediment in the Beaufort-Mackenzie Basin was derived from the adjacent mountains. Differences in populations of 0-300 Ma zircon grains between the Kugmallit-Mackenzie Bay and Iperk sequences suggest the drainage basins in this region evolved as the river system responsible for the Kugmallit-Mackenzie Bay sequences was redirected and an alternate river system delivered sediment to the Pliocene Iperk sequence. This change was likely caused by tectonic rock and surface uplift in the region associated with a Late Miocene-Early Pliocene episode of regional deformation.

Rights

© 2025, Joseph Martina

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