THE CRUSTAL STRUCTURE OF ELLESMERE ISLAND FROM RECEIVER FUNCTION MODELLING

The geological and topographic expression of Ellesmere Island and the surrounding area was mainly shaped in the last 500 Ma. During the Palaeozoic Ellesmerian orogeny several blocks assembled and accreted to the Franklinian margin of Laurentia as an equivalent to the Caledonian orogeny the North Atlantic region. The intraplate Eurekan orogeny in the Cenozoic caused additional crustal shortening in the area, related to the opening of Baffin Bay, the North Atlantic and the Arctic Ocean basins and the complex plate tectonic responses to these plate boundary reconfigurations. Geophysically Ellesmere Island is poorly investigated, which leads to large ambiguity and uncertainty of geological interpretations, especially on a crustal and lithospheric scale. To fill this information gap a seismological survey (ELLITE) was performed. A north-south oriented and ~520 km long array, consisting of 7 broadband stations was installed and maintained from 2010 to 2012 with the support of the Geological Survey of Canada and SEIS-UK. The two closest permanent stations (Eureka and Alert) in the area as well as two wide angle seismic profiles across the Canadian Arctic margin have been included to the interpretation. Preliminary results give estimates of Moho depths and crustal velocity structure and these are discussed with a focus on the relationship to topography, regional geological units and fault zones. The receiver functions reveal crustal roots underneath the Victoria and Albert Mountains (45km) and the Grantland Uplift (41 km), continuing to the Arctic Ocean coast line (37 km). The crustal thickness beneath the Hazen Trough seems rather uniform at 35 km. Crustal thinning occurs beneath the Sverdrup Basin (31 km) in the vicinity of Eureka, where a sedimentary cover of ~9 km is estimated. Crystalline basement appears to lie at least 20 km deep in the south, beneath the Central Ellesmere Fold and Thrust Belt; 15 km in the central part beneath the Hazen Trough; and at 10 km depth beneath Pearya.