The northern North American Cordilleran margin has been active for >200 million years, as recorded by punctuated phases of crustal growth and deformation. Accretion of the exotic Wrangellia Composite Terrane (Insular Belt) is considered the largest addition of juvenile crust to the Cordilleran margin, though margin-parallel translation during the Cenozoic has obscured much of the accretionary history. Three zones of inverted metamorphism spatially correspond to the Insular−North American suture zone from north to south: (1) Clearwater Mountains; (2) Kluane Lake; and (3) Coast Mountains, each preserving kinematics indicative of thrusting of North American−derived rocks over Insular-derived assemblages. We performed in situ monazite petrochronology on samples collected across strike in both the Clearwater and Coast Mountain regions. New and recently published data from these three metamorphic belts indicate that thrust-sense deformation accompanied the formation of inverted metamorphic isograds from 72 to 56 Ma. We leverage recent estimates of Denali fault offset to reconstruct a >1000-km-long zone of inverted metamorphism and interpret it as the Insular−North America terminal suture.
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Research Article|
October 11, 2024
Early Publication
Orogen-scale inverted metamorphism during Cretaceous−Paleogene terminal suturing along the North American Cordillera, Alaska, USA
Sean P. Regan;
Sean P. Regan
1
Geophysical Institute, University of Alaska Fairbanks, 1930 Yukon Drive, Fairbanks, Alaska 99775, USA2
Department of Geosciences, University of Alaska Fairbanks, 1930 Yukon Drive, Fairbanks, Alaska 99775, USA
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Mark E. Holland;
Mark E. Holland
3
Geology Department, St. Lawrence University, 23 Romoda Drive, Canton, New York 13617, USA
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Trevor S. Waldien;
Trevor S. Waldien
4
Department of Geology and Geologic Engineering, South Dakota School of Mines and Technology, 501 E. Saint Joseph Street, Rapid City, South Dakota 57701, USA
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McKenzie Miller;
McKenzie Miller
1
Geophysical Institute, University of Alaska Fairbanks, 1930 Yukon Drive, Fairbanks, Alaska 99775, USA2
Department of Geosciences, University of Alaska Fairbanks, 1930 Yukon Drive, Fairbanks, Alaska 99775, USA
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Peter Taylor;
Peter Taylor
5
P.O. Box 22290, Juneau, Alaska 99802, USA
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Andrew Kylander-Clark;
Andrew Kylander-Clark
6
Department of Earth Sciences, University of California−Santa Barbara, 1006 Webb Hall, Santa Barbara, California 93106, USA
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Sean Marble;
Sean Marble
1
Geophysical Institute, University of Alaska Fairbanks, 1930 Yukon Drive, Fairbanks, Alaska 99775, USA2
Department of Geosciences, University of Alaska Fairbanks, 1930 Yukon Drive, Fairbanks, Alaska 99775, USA
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Florian Hofmann
Florian Hofmann
1
Geophysical Institute, University of Alaska Fairbanks, 1930 Yukon Drive, Fairbanks, Alaska 99775, USA
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Sean P. Regan
1
Geophysical Institute, University of Alaska Fairbanks, 1930 Yukon Drive, Fairbanks, Alaska 99775, USA2
Department of Geosciences, University of Alaska Fairbanks, 1930 Yukon Drive, Fairbanks, Alaska 99775, USA
Mark E. Holland
3
Geology Department, St. Lawrence University, 23 Romoda Drive, Canton, New York 13617, USA
Trevor S. Waldien
4
Department of Geology and Geologic Engineering, South Dakota School of Mines and Technology, 501 E. Saint Joseph Street, Rapid City, South Dakota 57701, USA
McKenzie Miller
1
Geophysical Institute, University of Alaska Fairbanks, 1930 Yukon Drive, Fairbanks, Alaska 99775, USA2
Department of Geosciences, University of Alaska Fairbanks, 1930 Yukon Drive, Fairbanks, Alaska 99775, USA
Peter Taylor
5
P.O. Box 22290, Juneau, Alaska 99802, USA
Andrew Kylander-Clark
6
Department of Earth Sciences, University of California−Santa Barbara, 1006 Webb Hall, Santa Barbara, California 93106, USA
Sean Marble
1
Geophysical Institute, University of Alaska Fairbanks, 1930 Yukon Drive, Fairbanks, Alaska 99775, USA2
Department of Geosciences, University of Alaska Fairbanks, 1930 Yukon Drive, Fairbanks, Alaska 99775, USA
Florian Hofmann
1
Geophysical Institute, University of Alaska Fairbanks, 1930 Yukon Drive, Fairbanks, Alaska 99775, USA
Publisher: Geological Society of America
Received:
29 Jul 2024
Revision Received:
18 Sep 2024
Accepted:
25 Sep 2024
First Online:
11 Oct 2024
Online ISSN: 1943-2682
Print ISSN: 0091-7613
© 2024 Geological Society of America
Geology (2024)
Article history
Received:
29 Jul 2024
Revision Received:
18 Sep 2024
Accepted:
25 Sep 2024
First Online:
11 Oct 2024
Citation
Sean P. Regan, Mark E. Holland, Trevor S. Waldien, McKenzie Miller, Peter Taylor, Andrew Kylander-Clark, Sean Marble, Florian Hofmann; Orogen-scale inverted metamorphism during Cretaceous−Paleogene terminal suturing along the North American Cordillera, Alaska, USA. Geology 2024; doi: https://doi.org/10.1130/G52614.1
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