Plate Boundaries Around the Chukchi Borderland; An Integrated Geophysics Cruise to Test Models for the Formation of the Canada Basin

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Coakley 0909568University of Alaska FairbanksThe Chukchi Borderland is a block of extended continental crust embedded in the oceanic crust of the Canada Basin. As the piece that does not fit the simple ?windshield wiper? model for the Mesozoic opening of this basin, it figures prominently in all tectonic models proposed for the opening of the Amerasian Basin. Funds are provided to use multi-channel seismic (MCS) reflection techniques to test these hypotheses. By imaging the sedimentary section and tracing the continuity of structure, crustal thickness and stratigraphy across the edges of this high-standing continental block, it should be possible to distinguish between strike-slip, extensional and compressional boundaries. By tying the basinal stratigraphy to well-dated sediments on the Chukchi Shelf, it will be possible to propagate seismic stratigraphic age control into the Arctic Ocean basin to date the extensional dissection of the Borderland and lay the groundwork for scientific drilling.The four edges of the Chukchi Borderland present distinct scientific opportunities as well as possibilities for broader impact. Two particular edges have been selected as offering the best pay-off, although only one may be surveyed given the limited ship days available to this project: The transition from the Chukchi Shelf to the Chukchi Borderland ? Potential fields data (eg. gravity and magnetic anomaly data) suggest a discontinuity between the North American continental crust of the Chukchi Shelf and the adjacent Chukchi Borderland crust of uncertain affinity. In addition to directly observing any structures that define the transition, collecting the proposed data would also make it possible to link the substantial historical 2-D MCS grid on the shelf and the age control there to the stratigraphy of the Arctic Ocean. This is the least challenging area for sea ice. This region should be open water during the August-September period.The northern edge of the Chukchi Borderland ? Bathymetry data appear to show extensional structures from the interior basins within the Borderland plunging below the sediment cover off the continental high. This is in conflict with some models, which require a transform fault at the northern limit of the bathymetric high.