Aspects of the thermal history of the eastern margin of Canada based on apatite fission track and (uranium-thorium)/helium thermochronology.

• Main Author: Grist, Alexander Michael.
• Other Authors: Ph.D.
• Format: Text
• Language: English
• Published: Dalhousie University 2014
• Subjects: Geology; Arctic; Baffin Bay; Canada; Canadian Arctic Archipelago; Ellesmere Island; Greenland; Kane; Nares; Smith Sound; Arctic Archipelago; Baffin; Kane Basin; Labrador Sea; Nares strait; Smith sound; sverdrup basin
• Online Access: http://hdl.handle.net/10222/54638

Apatite fission track (FT) and (U-Th)/He thermochronology and vitrinite reflectance (Ro) are used to study cooling and inferred denudation in 3 areas; (1) the Triassic-Early Jurassic Fundy Basin, a failed rift subsequently exhumed as part of the onshore southern Canadian Atlantic margin; (2) the Late Paleozoic-Mesozoic Sverdrup Basin, an inverted intracratonic failed rift that developed following the Ellesmerian Orogeny in the Canadian Arctic Archipelago; and (3) the Sverdrup Basin sediment source region around Nares Strait-Kane Basin-Smith Sound, an area affected by the Paleogene Eurekan Orogeny. A limitation of the Laslett et al. (1987) FT annealing model is elucidated, and I demonstrate that low-temperature estimates from that model are inconsistent with measured (U-Th)/He ages. An initial model track length of 15 mum eliminates unrealistic late-stage FT model cooling and produces temperature histories compatible with (U-Th)/He data. The importance of measuring 147Sm in (U-Th)/He-dated samples is also demonstrated. Up to 20% of the radiogenic 4He in my samples was 147Sm-derived. Failure to consider this 4He source would cause considerable overestimation of (U-Th)/He ages. (U-Th)/He data and FT models for the southern Canadian Atlantic margin demonstrate that following the onset of Atlantic rifting, the region experienced rapid Jurassic exhumational cooling. FT and Ro data from the Sverdrup Basin demonstrate substantial cooling from inversion during the Eurekan Orogeny. Many thrust faults drilled during hydrocarbon exploration in the basin in the 1970's were active during the Eurekan Orogeny, which post-dates primary hydrocarbon maturation and migration, and are therefore poor targets. (U-Th)/He data and FT models for the Kane Basin-Smith Sound region suggest the complex thermal history results from at least 3 tectonic influences; (1) Late Paleozoic-Early Mesozoic regional exhumation related to Sverdrup Basin development; (2) Late Cretaceous cooling of rift flanks following the onset of Labrador Sea-Baffin Bay rifting; and (3) Paleocene inversion related to Eurekan convergence between Ellesmere Island and Greenland. FT ages related to the orogeny from fault-bounded basins near Nares Strait are older than ages from thrust fault hanging walls in central Ellesmere Island, suggesting cooling progressed east-west. Thesis (Ph.D.)--Dalhousie University (Canada), 2004.