NSF CONTINENTAL DYNAMICS FIELD LABORATORIES, 20 YEARS ON: THE BERING SHELF AND SURROUNDING LANDMASSES- A TRIBUTE TO MULTIDISCIPLINARY INTERNATIONAL COLLABORATIVE EFFORTS

The 1994 deep crustal seismic reflection profile across the Bering Shelf from North America's Pacific to Arctic margin represented an exploratory scientific venture across a frontier region, driven by the controversy presented by the geology of Alaska. A prime example of Cordilleran-style Mesozoic crustal growth by the accretion of allochthonous terranes, why was Alaska so topographically subdued that a ship could cross the orogen at this latitude? Geologic relations suggested crustal extension, but this was controversial at the time.

The CD project, which involved geologic field work and crustal seismic reflection and refraction, helped us understand the basic crustal architecture of the region, where extension was focused, and what was its end result. Given the inaccessibility of Alaska's geology, this was an arguably cost-effective and an appropriate way of answering these questions.

Our data and interpretations were published in GSA Special Paper 360 (2002) together with solicited papers. Since this synthesis, the Bering Shelf project has continued to serve as a foundation for new studies. Crustal extension can be examined at all crustal levels in the Bering Strait region: P-T paths of rocks in gneiss domes, the history of magmatism, and the formation and equilibration of the deep crust as revealed by xenoliths are linked together in time by an extensive and growing data base of U-Pb geochronology and in 3D by the deep crustal seismic data. This enables these disparate data sets to be integrated in insightful fashion and demonstrate the extent to which crustal remobilization and addition of juvenile material takes place in the deep crust during extension and magmatism. Ten years after, the project is still continuing to pave the way for new ventures into the plate tectonic history of the Arctic Oceans and the writing of a new CD proposal to examine the intriguing question as to where exactly the North American- Eurasia plate boundary is located in NE Russia.

NSF's CD program has fostered the exploratory nature of our science while focusing on addressing outstanding geodynamic questions about the earth in a multidisciplinary fashion, bringing us much new data, discoveries and insight. It has strengthened our science by training us to work and think together in multidisciplinary ways and as international teams.