CRUSTAL STRUCTURE OF THE EUREKAN OROGEN, ARCTIC CANADA

Receiver function analysis of new seismological data provides images of crustal structure along a transect across Ellesmere Island. The gravity response of this crustal transect is consistent with regional gravity anomalies. The new data are, furthermore, integrated with existing crustal information to produce regional maps. Distinct crustal features are identified, such as crustal thickness variations, the presence of high velocity/density lower crust, thick metasedimentary layers as well as shallow younger sedimentary successions.

Moho depths can be interpreted in terms of Eurekan (Cenozoic) and Ellesmerian (Palaeozoic) deformation. A zone of thick metasedmentary layers in central Ellesmere Island correlates with areas of dominantly Ellesmerian accretion. A WSW-ENE orientated zone of shallow Moho (Hazen Stable Block) underlies crust strongly deformed in the Palaeozoic but essentially undeformed in the Cenozoic. A block of thick crystalline crust in the north of Ellesmere Island is clearly separated from the North American-Greenland Craton, possibly a hint for a northern microcontinent. High velocity lower crust may be related to igneous activity during several rift episodes and/or impact by High Arctic Large Igneous Province magmatism. A correlation appears to exist between topography, Moho depth and the location of dykes in Nansen Sound suggesting the same tectono-magmatic origin of these features. Lincoln Sea shows consistently thin crust likely related to rifting.