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TitleIntegrated thermal history analysis of the Beaufort-Mackenzie basin using multi-kinetic apatite fission track thermochronology
AuthorIssler, D M; Grist, A M
SourceGoldschmidt Conference Abstracts; Geochimica et Cosmochimica Acta vol. 72, no. 12S, 2008 p. A413
Alt SeriesEarth Sciences Sector, Contribution Series 20080251
MeetingGoldschmidt Conference 2008; Vancouver; CA; July 13-18, 2008
ProvinceNorthwest Territories
AreaMackenzie Valley; Beaufort-Mackenzie Basin
Subjectsgeochronology; fossil fuels; fission tracks; fission-track dates; thermal history; thermal maturation
AbstractSixty apatite fission track (FT) samples (mainly cores from Cenozoic, Cretaceous and Devonian rocks) were collected from twenty-five petroleum exploration wells distributed across the Beafort-Mackenzie Basin (BMB), northern Canada, as part of an integrated study of petroleum systems. In addition, vitrinite reflectance and shale compaction data were obtained to help constrain maximum paleotemperatures and erosion magnitudes. Sample apatite grains are heterogeneous in composition and yield mixed FT age populations. Older age grains have elevated concentrations of elements (e.g. Fe, Mg, Mn, Cl) that make them more FT retentive (higher annealing temperature) than typical fluorapatite. Elemental data were used to calculate rmr0 values [1] corresponding to apatite populations with different FT annealing kinetics. FT age populations determined using the rmr0 parameter show good agreement with those derived using the binomial peak-fitting program, BINOMFIT [2]. In general, the rmr0 parameter produced more consistent and better defined kinetic populations than other commonly used parameters (e.g. Cl content, FT etch figure size).
Thermal histories were obtained for the FT samples using an inverse Monte Carlo model [3] incorporating the multi-kinetic FT annealing scheme of Ketcham et al. [1] that treats each kinetic population in a sample as a separate thermochronometer, thus enhancing thermal history resolution. Model solutions are consistent with observed FT age and length parameters and conform to other geological constraints (present temperature, thermal maturity, rate bounds from preserved stratigraphy). The multi-kinetic FT samples constrain both the post-depositional heating and cooling histories of the Cretaceous-Cenozoic sedimentary successions comprising the BMB as well as the cooling histories of the exhumed source areas from which these sediments were derived.

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