J. Michael W. Collins

1993 - The David Barlow Memorial Award

B. Sc. Honours Thesis

Apatite fission track study of tectonics and provenance of sediments in the Sawtooth Range, Sverdrup Basin, Canadian Arctic Archipelago

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The Sverdrup Basin in the Canadian Arctic is a large intracratonic rift basin initiated during the late Paleozoic. Its sediments were deposited in two sequences: Proterozoic to mid-Paleozoic deformation in the Ellesmerian Orogenies, and a late Paleozoic to early Cenozoic sequence, affected by the Eurekan Orogeny. The source of sediments is understood to be from the exhumed pre-Paleozoic basement along the cratonic margins, although a possible derivation from an Arctic Ocean rift margin in the northwest has been proposed, and there is some volcanic input. Detrital apatite samples have been obtained from two transects in the northern and southern Sawtooth Range. The first section traverses the Vesley Fiord Thrust, with Cretaceous-Tertiary rocks in the footwall and Permo-Triassic rocks in the hangingwall. The second transect combines two measured sections, with Triassic to Miocene rocks, in the footwall, and Permian to Triassic-Jurassic rocks in the hangingwall of the East Cape Thrust.

The apatite samples were analysed for fission track histories and for compositional variation. The analysis of fission tracks in apatite grains yields information on burial, cooling and exhumation events in sedimentary rocks. By contrasting fission track cooling histories of samples offset by the two thrusts it has been possible to constrain the timing of thrusting and exhumation in the central Sverdrup Basin. The study shows that oil generation from Cretaceous source rocks predated the formation of structural traps in the Sawtooth Range, thus explainingthe lack of success of 30 years of oil exporation in the area.

The major and trace element composition (e.g. F, Cl, OH, CO2 , Sr, La, Ce, Nd, Y) of detrital and igneous apatite used in the study was obtained with the microprobe. Fluoroapatite predominates in the strata from Permian to Miocene, and no major shifts in provenance can be discerned on the basis of trace elements. The use of radial plots allows for the identification of discrete populations of apatite based on their FT ages, and suggests there may be several distinct source areas for sediments in this locality during the Tertiary.

Keywords: Apatite fission track analysis, provenance, age of thrusting, Sverdrup Basin, Eurekan orogeny, apatite, rare earth elements.
Pages: 141
Supervisor: Marcos Zentilli