Tectonic deformation and paleostress field evolution of the western Pearya terrane, Arctic Canada
Final Report Abstract
The aim of this project was to analyse the deformation style of the western Pearya terrane in the Canadian High Arctic and to delineate the different deformation phases based on a paleostress field analysis. The outcrop conditions were best along the Eurekan strike-slip faults and they were therefore in the focus of this investiogation. The Eurekan deformation is a Cenozoic tectonic phase that affected large parts of the Arctic region. In the study area on northern Ellesmere Island, major NE-SW trending strike-slip faults occur. The outcrop data show that left-lateral strike-slip faults slightly dominate, but also faults with right-lateral kinematics were documented. Cross-cutting relationships of the individual faults give evidence for multiple fault reactivations within major strikeslip zones. The reconstructed paleostress fields show two phases. The first phase started with a N-S compression/E-W extension and shifted over a NNE-SSW compression/WNW-ESE extension into a NNW-SSE compression/WSW-ENE extension. The second phase was a WNW-ESE compression/NNE-SSW extension. The paleostress field evolution reflects the movements of Greenland. During the Eurekan stage 1 deformation, Greenland moved northward and during Eurekan stage 2 deformation it moved to the WNW. These motions likely controlled the stress field on northern Ellesmere Island. From the paleostress field analyses and the orientation of the strikeslip faults in the study area, it can be derived that the Eurekan stage 1 deformation is characterized by left-lateral faults, whereas most-likely during the Eurekan stage 2 deformation, the majority of right-lateral faults formed. The paleostress field analysis implies that many Eurekan faults are reactivated Ellesmerian faults. Recent seismic events indicate ongoing tectonic activity at some of the major strike-slip faults. This sheds new light on the geodynamics of the north Canadian Arctic margin, which was mechanically coupled to the Greenland plate, and implies that under the recent stress field, earthquakes at strike-slip faults are still possible and some of these faults were active in three phases over the last 350 Myr.
