The lithosphere of Ellesmere Island and adjacent northwestern Greenland (CALE “A” transect onshore)
Ellesmere Island, in Canada’s Arctic, comprises a series of ~SW-NE trending tectonic provinces, the crustal structure and geological expression of which represent a combination of interplate, accretionary orogenesis in the Palaeozoic (Caledonian equivalent and Ellesmerian orogenies) and intraplate o...
| Summary: | Ellesmere Island, in Canada’s Arctic, comprises a series of ~SW-NE trending tectonic provinces, the crustal structure and geological expression of which represent a combination of interplate, accretionary orogenesis in the Palaeozoic (Caledonian equivalent and Ellesmerian orogenies) and intraplate orogenesis in the Cenozoic (Eurekan Orogeny). The present-day topography of Ellesmere Island is closely related to the crustal architecture of these tectonic provinces, which includes the adjacent polar continental margin. A two-dimensional lithosphere-scale model is presented that crosses Ellesmere Island from northern Baffin Bay to the Arctic Ocean, part of Transect “A” of the Circum-Arctic Lithosphere Evolution (CALE) project. The model is based on gravity and magnetic data constrained by mapped geological structure as well as a not yet unpublished Receiver Function study, based on teleseismic data acquired between 2010 and 2012 by a passive seismological array on Ellesmere Island called “ELLITE”. In northern Baffin Bay and on parts of the polar margin of Ellesmere Island (and adjacent northwestern Greenland), published crustal scale seismic refraction velocity models also provide some constraint to the lithosphere model. The most recent tectonic event governing the geological and physiographic character of Ellesmere Island is the Eurekan Orogeny, an intraplate orogeny that developed as a consequence of North Atlantic-Arctic plate reorganisations and the resulting convergence of Greenland against Ellesmere Island in the Palaeogene. The basement of the Eurekan orogen comprises Precambrian-aged lithosphere in its northernmost (Pearya terrane) and southeasternmost (Greenland-Canada craton) parts as well as possibly younger lithosphere accreted during Palaeozoic orogenesis in central Ellesmere Island. Its southern margin, marking the southern terminus of the constructed lithosphere model, comprises the late Precambrian-Early Palaeozoic passive continental margin of Laurentia. The preliminary Receiver Functions show signatures of strong intracrustal velocity discontinuities, possibly indicating major vertical structural differences in in the central part of Ellesmere Island, which are absent in the north and south. The lithosphere model is interpreted in the context of plate convergence processes in the Palaeozoic and large-scale intraplate shortening in the Cenozoic with extensional tectonics dominating throughout the Mesozoic. |
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