| Title | Burial and exhumation history of the Mackenzie Plain, NWT, Canada: integration of apatite (U-Th)/He and fission track thermochronometry |
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| Author | Powell, J ;
Schneider, D; Issler, D; Stockli, D |
| Source | Thermo 2016: 15th International Conference on Thermochronology, abstracts; 2016 p. 141-142  Open Access |
| Links | Online - En ligne (complete volume -
volume complet, PDF, 36.9 MB)
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| Year | 2016 |
| Alt Series | Natural Resources Canada, Contribution Series 20190422 |
| Meeting | Thermo 2016: 15th International Conference on Thermochronology; Maresias; BR; September 18-23, 2016 |
| Document | book |
| Lang. | English |
| Media | on-line; digital |
| File format | pdf |
| Province | Northwest Territories |
| Area | Mackenzie Plain |
| Subjects | geochronology; sedimentology; Science and Technology; Nature and Environment |
| Program | GEM2: Geo-mapping for Energy and Minerals Mackenzie Corridor, Shield to Selwyn |
| Released | 2016 09 01 |
| Abstract | Sedimentary strata from the Mackenzie Plain, currently in the foreland of the Mackenzie Mountains of the northern Canadian Cordillera, record a dynamic geologic history from the Paleozoic through to the
Paleogene. Whereas Late Cretaceous to Paleogene foreland basin strata presently cover the Plain, uncomformities throughout the sedimentary succession indicate that episodic burial and exhumation are a common theme through deep time. Knowledge of the
timing and magnitude of these events is especially critical for understanding potential hydrocarbon systems, as the timing of maturation for the Devonian source rock is a major uncertainty for oil and gas exploration. Howeer, quantitative
thermochronology studies for the region are sparse, and limited to Neoproterozoic strata from the mackenzie Mountains and a single well in the Mackenzie Plain. To better understand the tectonic and thermal evolution of the study area, samples were
collected for apatite (U-Th)/He (AHe) and fission track (AFT) thermochronometry. Strategic sampling followed a transect along the deformation front and across the Plain. We targeted outcrops of the Devonian Imperial Formation and the Late Cretaceous
Slater River Formation. These formations straddle a significant regional unconformity, and ultimately help to quantify the magnitude of the late Paleozoic to early Mesozoic thermal history in comparison with the Late Cretaceous to Paleocene thermal
event related to foreland basin development. We report 61 single-grain AHe dates from seven samples. AHe dates vary from 225 ± 14 Ma to 3 ± 0.2 Ma, with the majority of dates recording cooling between the Late Cretaceous to Miocene. Whereas several
samples exhibit correlations between AHe date and parameters such as radiation damage (eU) and grain size, all samples demonstrate varying degrees of intra-sample date dispersion. All five samples chosen for AFT thermochronology display an even
greater degree of variation, with AFT dates scattered between the Cambrian and Miocene throughout out dataset. Although no correlations exist between DPAR and AFT age or track length distribution, we note a strong relationship between grain chemistry
and ages. We use the parameter rmr03 to distinguish up to four discrete kinetic populations per sample, with consistent Triassic, Cretaceous and Miocene pooled ages. Inverse thermal history modeling of AFT and AHe samples reveals that the Devonian
strata likely reached maximum burial temperatures (130ºC-180ºC) prior to Triassic unroofing. Strata were reheated to lower temperatures in the Cretaceous to Paleogene (90ºC-120ºC), and have a dog-legged Cenozoic cooling history, with an initial
Paleocene phase related to Cordilleran deformation and a final Miocene phase. This t-T information is used to assess 1D burial histories of local wells and the hydrocarbon potential of regional Devonian and Cretaceous source rocks. Ultimately, these
data reflect the complications, and possibilities, of low-temperature thermochronology in sedimentary rocks where detrital variance results in a broad chemistry range in the apatite population. We used chemistry-dependent fission track annealing
kinetics to explain dispersion in both our AFT and AHe datasets and detail the thermal history of strata that have experienced a protracted cooling history through the uppermost crust. |
| GEOSCAN ID | 321697 |
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