NEW INSIGHTS INTO ARCTIC TECTONICS: U/PB, (U-TH)/HE, AND HF ISOTOPIC DATA FROM THE FRANKLINIAN BASIN, CANADIAN ARCTIC ISLANDS

Sedimentary successions of the Franklinian Basin represent >200 Myr of geological history­ along the northern margin of the North American Craton yet the tectonic and thermal evolution of this basin remains poorly constrained. An initial data set of more than 1800 detrital zircon U-Pb ages collected from the sedimentary strata of the Franklinian Basin of the Canadian Arctic Islands provide important insights into the provenance of sediments along the northern Laurentian margin from the late Neoproterozoic to the Late Devonian. The initial U-Pb detrital zircon data set suggests the Franklinian Basin succession is composed of strata with three distinctly different U-Pb age populations derived from the west Greenland/northeast Canadian Shield, the east Greenland Caledonides and the Pearya Terrane, and an unknown northern continental landmass.

Our initial U-Pb data set is augmented by an additional ~500 detrital zircon U-Pb ages, 64 detrital zircon (U-Th)/He ages, 21 detrital apatite (U-Th)/He ages, and 45 Hf isotopic ratios. The new data help constrain the tectonic histories of the source regions for the Franklinian Basin and help to provide a thermal history of the basin itself.

Our recent U-Pb analyses from the Middle-Late Devonian clastic deposits provide additional information on complexities associated with the onset and conclusion of Middle to Late Devonian clastic sedimentation. The (U-Th)/He zircon ages have not been reset since deposition and indicate that despite the fact that sediment was derived from multiple terranes, these source areas experienced exhumation at similar times. Apatite (U-Th)/He ages have been reset since deposition and provide information on the relatively slow exhumation history of the basin itself. The Hf isotopic analyses were used to determine the geological processes responsible for the growth of 360-450 Ma, 500-550 Ma, and 650-700 Ma zircon in the source regions for the basin.