Polyphase deformation in the Lake Hazen region, at 82o north on Ellesmere Island: implications for the tectonic evolution of the High Arctic

The Canadian Arctic Islands are a vast remote wilderness, much of which has only been mapped at a reconnaissance level by the Geological Survey of Canada. As a result, there is a paucity of detailed structural data for the region. Renewed interest in the potential geological resources of the Arctic has led to increasing scientific activity in the region in recent years. The data emerging from these studies are crucial to constraining models for the tectonic evolution of the region and will ultimately help us to understand the potential resources of the Arctic.

In summer 2009, geologists from CASP completed a 7 week expedition to Lake Hazen, situated at 82o north in northeast Ellesmere Island. The focus of the fieldwork was to document the structure, stratigraphy, provenance and sedimentology of the rocks in the region. This work represents the most detailed study of this area to date. Preliminary results from this field season provide fresh insights into the tectonic evolution of the area and provide important constraints for tectonostratigraphic models of the Canadian Arctic during the Phanerozoic.

The geology of the Lake Hazen region includes Neoproterozoic and lower Palaeozoic meta-sediments of the Franklinian succession, late Palaeozoic to Cretaceous deposits of the Sverdrup succession, and latest Cretaceous to Paleogene deposits of the Lake Hazen Basin. Cretaceous dykes and sills associated with opening of the Arctic Ocean are also widespread in the region. Structural transects produced during the 2009 field season highlight a long polyphase deformation history in northeast Ellesmere Island, including ductile contractional structures produced during the late Devonian Ellesmerian Orogeny, extensional structures related to late Palaeozoic rifting and basin evolution, and brittle contractional structures formed during the Cenozoic Eurekan Orogeny.

CASPs fieldwork programme in the Canadian Arctic is part of an ongoing project to understand the timing, extent and cause of the Ellesmerian Orogeny in the late Devonian and early Carboniferous, the tectonostratigraphic evolution of the Sverdrup Basin in the late Palaeozoic and throughout the Mesozoic, and to constrain models for the opening of the Arctic Ocean in the Cretaceous.