Title: Inherited Tectonics and the Control on Late Devonian Deposition in the Intracratonic Williston Basin, USA and Canada

Michael H. Hofmann

University of Montana, United States of America

Event: Abstract GeoUtrecht2020

Date: 2020

DOI: 10.48380/dggv-xqz1-7b83

The Williston Basin is an intracratonic basin in Canada and the USA, located atop the structurally complex suture zone between the Archean Superior province to the east and the Archean basement of the Wyoming structural provinces to the west. The basin in general has a very homogeneous subsidence history throughout most of the Paleozoic, that can be largely explained by simple thermal subsidence.

This simple subsidence model should result in a very predictive facies distribution with more proximal facies near the basin margin and the more distal deposition near the basin center. Although this type of regional facies distribution is present during large parts of the Devonian, including the Famennian Lower Bakken Shale deposition, the Pronghorn Member of the Bakken Formation does not adhere to this model.

Results from detailed (sub-centimeter scale) lithofacies descriptions and chemostratigraphy from 26 cores from North Dakota and Saskatchewan suggests that the Pronghorn Member changes in facies, composition, and thickness along known structural lineaments, such as the Weldon-Brockton-Froid Zone and the Goose Lake Trend. The data presented here suggests that these lineaments were active during the latest Devonian and dissected the Williston Basin into multiple sub-basins during Pronghorn deposition.

This detailed facies and chemostratigraphy study provides a new careful look on the controls of late Devonian deposition in the Williston Basin, and food for thought how tectonics might influence deposition in an intracratonic basin located hundreds of miles from an orogenic front.

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