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An Aerogeophysical Study of the Eurasia Basin John M Brozena 1 (202-404-4346; john.brozena@nrl.navy.mil) Vicki A Childers 1 (202-404-1110; vicki@qur.nrl.navy.mil) Jan Inge Faleide 2 Annik Myrhe 2 Lawrence A Lawver 3 (512-471-0433; lawver@utig.ig.utexas.edu) 1Naval Research Laboratory, Code 7421 4555 Overlook Ave. SW, Washington, DC 20375-5350, United States 2University of Oslo, Dept. of Geology P.O. Box 1047 - Blindern, Oslo N-0316, Norway 3University of Texas Institute for Geophysics, 4412 Spicewood Springs Rd. #600, Austin, TX 78759-8500, United States In spite of the well established first-order view of the Eurasia Basin, much of the detail of the structure and evolution of this ocean and its margins remains enigmatic due to the permanent ice cover of most of the region. With the exception of a few ice-breaker based seismic cruises and the new submarine bathymetry, side-scan and gravity traverses of the basin provided by the SCICEX program, little additional geophysical data have been obtained over the region in the last two decades. However, because of the importance of this area for research in paleoclimate, environmental pollution issues, Arctic margin evolution and the potential economic geologic resources of the Barents Sea, Kara Sea and Siberian margins, several new programs of study have been proposed or have begun. Airborne gravity and magnetics data collected by a new aerogeophysical field program, conducted by the Naval Research Laboratory, provide a detailed structural and evolutionary framework for the basin and its margins that will aid in the interpretation of the more detailed in-situ measurement programs ongoing and proposed for the region. The new data cover a 1,200,000 km**2 region between the Eurasia margin and the Canada Basin/Fletcher Abyssal Plain with a typical line spacing of 18 km. Most of the region is within the polar gap in the ERS-1/2 and the gravity thus provides a regional view of the structural elements of the basin including Nansen-Gakkel Ridge, Lomonsov Ridge, Yermak Plateau, Morris-Jessup Rise, and the Eurasian margin between Svalbard and Franz Josef Land. The new data also allow the production of a much improved magnetic anomaly map for the basin. An initial look at the data reveals a complex rifted structure for Lomonosov Ridge with significant misfit when restored to the Eurasia margin. There is a space problem in the southern part of the basin that is only partially resolved by the known continental extension within Yermak Plateau and likely requires an early opening connection through Nares Strait or eastern Canada Basin. Nansen-Gakkel Ridge is segmented along its length by changes in strike obliqueness rather than by offsets. We speculate that the initial rifting of the Lomonosov Ridge may have occurred in a back-arc basin environment or alternatively, an older ocean basin may have existed between some portion of the Lomonosov Ridge and the Eurasia margin prior to rifting and connection with the North Atlantic. |
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