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Sedimentary and Crustal Structure from the Ellesmere Island and Greenland Continental Shelf onto the Lomonosov Ridge, Arctic Ocean

Trine Dahl-Jensen1, H. Ruth Jackson2, Working Group: Deping Chian3, John Shimeld3, Thomas Funck3, Christian Marcussen3, Isa Asudeh3, and Dave Snyder3
1Geological Survey of Denmark and Greenland, Copenhagen K, Denmark.
2Geological Survey of Canada, Dartmouth, NS, Canada.
3The Geological Surveys of Canada & Denmark and Greenland, Copenhagen, Dartmouth and Ottawa, Denmark.

Two wide-angle reflection/refraction (WAR) lines were acquired on the passive continental margin north of Ellesmere Island and Greenland. The sound source was explosives and the receivers were vertical geophones placed on the sea ice. A 440-km-long north-south profile that crossed the shelf, a bathymetric trough and onto the Lomonosov Ridge was completed. In addition, data along a 110-km-long profile along the trough were acquired. P wave velocity models were created by forward and inverse modeling. On the shelf, modeling indicates a 12-km-deep sedimentary basin consisting of three layers with velocities of 2.1-2.2 km/s, 3.1-3.2 km/s and 4.3-5.2 km/s. Between the 3.1-3.2 km/s and 4.3-5.2 km/s layers there is a velocity discontinuity that dips seaward consistent with a regional unconformity. The 4.3-5.2 km/s layer is interpreted to be of Paleozoic to Mesozoic age based on local and regional geological constraints. Beneath these layers, velocities of 5.4-5.9 km/s are correlated with metasedimentary rocks that outcrop along the coast. These four layers continue from the shelf onto the Lomonosov Ridge. On the ridge, the bathymetric contours define a plateau with a width of 220 km. The plateau is a basement high with velocities of 5.9-6.5 km/s. A short reflection seismic profile on the plateau indicates sediment thicknesses of only a few hundred meters. Radial magnetic anomalies emanate from the plateau indicating the volcanic nature of this feature. A lower crustal velocity of 6.2-6.7 km/s, typical of rifted continental crust, is observed along the entire line. The Moho based on the WAR data has significant relief from 17 to 27 km that is confirmed by gravity modeling and consistent with the regional tectonics. In the trough, Moho shallows eastwards from a maximum of 19 km to 16 km. No indication of oceanic crust was found in the bathymetric trough.


AAPG Search and Discover Article #90096©2009 AAPG 3-P Arctic Conference and Exhibition, Moscow, Russia