| Titre | Burial and exhumation history of the Mackenzie Plain, NWT, Canada: integration of apatite (U-Th)/He and fission track thermochronometry |
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| Auteur | Powell, J ;
Schneider, D; Issler, D; Stockli, D |
| Source | Thermo 2016: 15th International Conference on Thermochronology, abstracts; 2016 p. 141-142  Accès ouvert |
| Liens | Online - En ligne (complete volume -
volume complet, PDF, 36.9 MB)
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| Année | 2016 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20190422 |
| Réunion | Thermo 2016: 15th International Conference on Thermochronology; Maresias; BR; Septembre 18-23, 2016 |
| Document | livre |
| Lang. | anglais |
| Media | en ligne; numérique |
| Formats | pdf |
| Province | Territoires du Nord-Ouest |
| Région | Mackenzie Plain |
| Sujets | géochronologie; sédimentologie; Sciences et technologie; Nature et environnement |
| Programme | GEM2 : La géocartographie de l'énergie et des minéraux Bouclier à Selwyn du corridor de Mackenzie |
| Diffusé | 2016 09 01 |
| Résumé | (disponible en anglais seulement)
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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