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Kinematic History and Tectonic Evolution of the Amerasian Basin: Investigating Palaeo-Plate Boundaries around the Chukchi Borderlands - Abstract
The Arctic Ocean has been influenced by both the Atlantic and Pacific Ocean plate systems during its tectonic history. The complex multi-stage opening of the basin is only partially understood, in part, due to the difficulty of utilizing traditional geologic and geophysical oceanographic techniques in ice-covered waters. While the kinematic development of the Eurasian Basin is well-understood to be the northernmost extension of the Mid-Atlantic Ridge, the history of the morphologically complex Amerasian Basin may be due to multiple events, significantly complicating interpretation of its history.
Any detailed model for the opening of the Amerasian Basin should look for structures that would accommodate spreading, as well as seek to explain the tectonic mechanisms that drove the basin’s development. Tholeiitic flood basalts of similar ages have been observed along the margins of the Arctic Ocean and are thought to represent a Large Igneous Province. Since LIPs are usually associated with continental rifting, a successful model for the basin might be based on reconstructing the geometry of the Cretaceous High Arctic Large Igneous Province and its associated radiating dike swarms. Detailed models should also consider pre-existing zones of weakness such as the suture zone and deformation front of the ancient Caledonides. These may underlie the shelf sediments and extend northward from the Eurasian Arctic Margin across the Barents Shelf coinciding with the bend in the Lomonosov Ridge. This would facilitate the development of transform faults on either side of the Mendeleev Ridge to accommodate spreading in the newly forming Amerasian Basin, as well as creating a rectangular pull-apart basin between the Mendeleev and Lomonosov Ridges.
We propose a revised plate model for the development of the Amerasian Basin. This model invokes a triple junction in the central Canada Basin. A magmatic source, localized under the Alpha Ridge generated the radiating dike swarms and tholeiitic flood basalts of similar Early Cretaceous age found on the DeLong Islands, Svalbard, Franz Joseph Land, Greenland, Sverdrup Basin and, possibly, the Alpha and Mendeleev Ridges that accompanied the onset of rifting in the Amerasia Basin. This resulted in a dilatational opening of the Canada Basin, the reactivation of previous structural trends, and the migration of the southern edges of the northeastern Siberian shelf along large right lateral transform faults that allowed crustal “escape” toward the Pacific subduction zone. Bathymetry, aeromagnetic and gravity data also support a complimentary zone of left lateral transform motion along the northern Alaska margin and southern edge of the Chukchi Borderlands which would also have accommodated spreading and southerly “escape”.
Acknowledgments and Associated Footnotes
1 Kelley Brumley: Department of Geology and Geophysics, University of Alaska Fairbanks
2 Bernard Coakley: Department of Geology and Geophysics, University of Alaska Fairbanks
3 Wesley Wallace: Department of Geology and Geophysics, University of Alaska Fairbanks
4 David Stone: Department of Geology and Geophysics, University of Alaska Fairbanks
Copyright © 2014 by the Alaska Geological Society