| Title | Thermal history of the Mackenzie Plain, Northwest Territories, Canada: insights from low-temperature thermochronology of the Devonian Imperial Formation |
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| Author | Powell, J W ;
Issler, D R; Schneider, D A; Fallas, K M; Stockli, D F |
| Source | Geological Society of America Bulletin vol. 132, issue 3-4, 2019 p. 767-783, https://doi.org/10.1130/B35089.1 |
| Image |  |
| Year | 2019 |
| Alt Series | Natural Resources Canada, Contribution Series 20180416 |
| Publisher | Geological Society of America |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Northwest Territories; Northwest Territories |
| NTS | 95M; 95N; 96C; 96D; 96E; 96F; 105P; 106A; 106H |
| Area | Mackenzie Mountains; Mackenzie River; Franklin Mountains; Norman Range |
| Lat/Long WENS | -130.0000 -124.5000 65.5000 63.5000 |
| Subjects | geochronology; Science and Technology; Nature and Environment; sedimentary basins; thermal history; tectonic history; burial history; fission-track dates; apatite; zircon; modelling; thermal maturation;
bedrock geology; lithology; sedimentary rocks; Mackenzie Plain; Imperial Anticline; Brackett Basin; Root Basin; Canadian Cordillera; Imperial Formation; Phanerozoic; Paleozoic; Devonian |
| Illustrations | location maps; geoscientific sketch maps; stratigraphic charts; tables; plots; time series; bar graphs; profiles |
| Program | GEM2: Geo-mapping for Energy and Minerals Mackenzie Corridor, Shield-to-Selwyn geo-transect, Mackenzie-Selwyn sub-activity |
| Released | 2019 07 17 |
| Abstract | Devonian strata from the Mackenzie Plain, Northern Canadian Cordillera, have undergone two major burial and unroofing events since deposition, providing an excellent natural laboratory to assess the
effects of protracted cooling history on low-temperature thermochronometers in sedimentary basins. Apatite and zircon (U-Th)/He (AHe, ZHe) and apatite fission track (AFT) thermochronology data were collected from seven samples across the Mackenzie
Plain. AFT single grain ages from six samples span the Cambrian to Miocene with few Neoproterozoic dates. Although there are no correlations between Dpar and AFT date or track length distribution, a relationship exists between grain chemistry and
age. We calculate the parameter r(mr0) from apatite chemistry and distinguish up to three discrete kinetic populations per sample, with consistent Cambrian-Carboniferous, Triassic-Jurassic, Cretaceous, and Cenozoic pooled ages. Fifteen ZHe dates
range from 415 ± 33 Ma to 40 ± 3 Ma, and AHe dates from 53 analyses vary from 225 ± 14 Ma to 3 ± 0.2 Ma. Whereas several samples exhibit correlations between date and radiation damage (eU), all samples demonstrate varying degrees of intra-sample date
dispersion. We use chemistry-dependent fission track annealing kinetics to explain dispersion in both our AFT and AHe data sets and detail the thermal history of strata that have experienced a protracted cooling history through the uppermost crust.
Thermal history modeling of AFT and AHe samples reveals that the Devonian strata across the Mackenzie Plain reached maximum burial temperatures (~90 °C-190 °C) prior to Paleozoic to Mesozoic unroofing. Strata were reheated to lower temperatures in
the Cretaceous to Paleogene (~65 °C-110 °C), and have a protracted Cenozoic cooling history, with Paleogene and Neogene cooling pulses. This thermal information is compared with borehole organic thermal maturity profiles to assess the regional burial
history. Ultimately, these data reflect the complications, and possibilities, of low-temperature thermochronology in sedimentary rocks where detrital variance results in a broad range of diffusion and annealing kinetics. |
| Summary | (Plain Language Summary, not published)
This work deals with reassessing and updating the identification of microfossils (conodonts) samples from the GSC collections, sampled and studied in the
nineteen seventies, to the current standards and literature. This allows a more detailed positioning of the Lower Devonian and lower Middle Devonian rock formations from the northern and southern Mackenzie Mountains (NW Territories) in the geological
timeframe and facilitates interregional and international correlations. |
| GEOSCAN ID | 313754 |
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