Phanerozoic surface history of the Slave craton
American Geophysical Union
New apatite (U-Th)/He (AHe) thermochronometry data and key geologic constraints from Slave craton kimberlites are used to develop a model for the Phanerozoic burial, unroofing, and hypsometric history of the northwestern Canadian shield. AHe dates range from 210 ± 13 to 382 ± 79 Ma, are older in the eastern Slave craton and decrease westward, and resolve the spatial extent, thickness, and history of now-denuded sedimentary units. Results indicate Paleozoic heating to temperatures ≥85–90°C, suggesting regional burial beneath ≥2.8 km of strata while the region was at sea level, followed by the westward migration of unroofing across the craton. This Paleozoic-Mesozoic history does not correlate with sea level change, instead requiring Paleozoic subsidence of the craton followed by surface uplift. The AHe data restrict Cretaceous burial to ≤1.6 km, followed by unroofing, Eocene terrestrial sediment deposition, and removal of Phanerozoic sedimentary cover across the region by present day. The craton underwent ≥300 m of post-100 Ma elevation gain, based on ~100 Ma marine sedimentary xenoliths entrained in ~75–45 Ma kimberlites at modern elevations of 550–600 m. The transition from Paleozoic-Mesozoic subsidence to surface uplift may signal a change from predominantly northern (Franklinian-Innuitian) to western (Canadian Cordillera) plate boundary controls on continental interior processes, with the latter driving the east-to-west wave of unroofing. Canadian Cordillera evolution also affected the Cretaceous-early Tertiary history. Dynamic topography due to changing mantle flow regimes and proximity to sediment sources influenced the Phanerozoic surface evolution of the northwestern Canadian shield.
Ault, A.K., Flowers, R.M., and Bowring, S.A., 2013, Phanerozoic surface history of the Slave craton: Tectonics, v. 32, p. 1066-1083, doi:10.1002/tect.20069.
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