|Title||Updating the Lower and lower Middle Devonian time-rock chart for the Mackenzie Mountains, NWT (Canada) based on conodont biostratigraphy|
|Author||Gouwy, S; Uyeno,
|Source||11th North American Paleontological Conference, program with abstracts; by Droser, M (ed.); Hughes, N (ed.); Bonuso, N (ed.); Bottjer, D (ed.); Eernisse, D (ed.); Gaines, R (ed.); Hendy, A (ed.); Jacobs,
D (ed.); Miller-Camp, J (ed.); Norris, R (ed.); Roy, K (ed.); Sadler, P (ed.); Springer, M (ed.); Wang, X (ed.); Vendrasco, M (ed.); PaleoBios vol. 36, Suppl. 1, 2019 p. 154 Open Access|
|Links||Online - En ligne|
|Alt Series||Natural Resources Canada, Contribution Series 20180415|
|Publisher||University of California|
|Meeting||NAPC19 - 11th North American Paleontological Convention; Riverside, CA; US; June 23-27, 2019|
|Media||paper; on-line; digital|
|Lat/Long WENS||-130.0000 -126.0000 65.0000 64.0000|
|Subjects||paleontology; sedimentology; stratigraphy; geochronology; Science and Technology; Nature and Environment; Middle Devonian; Lower Devonian; systematic stratigraphy; fossil assemblages; fossil zones;
bedrock geology; lithology; sedimentary rocks; limestones; dolostones; carbonates; biostratigraphy; micropaleontology; microfossils; conodonts; Phanerozoic; Paleozoic; Devonian|
|Program||GEM2: Geo-mapping for Energy and Minerals Mackenzie Corridor, Shield-to-Selwyn geo-transect, Mackenzie-Selwyn sub-activity|
|Released||2019 06 19|
|Abstract||The Lower Devonian and lower Middle Devonian in the Mackenzie Mountains (Northwest Territories, Canada) and adjacent areas is a succession of dolostone, limestone breccia and massive limestone with
minor basal sandstone. Based on new field data and a restudy of Geological Survey of Canada conodont collections, the time-rock chart for this succession is updated to the current conodont biozonation. |
The Lower Devonian is represented by a
peritidal carbonate platform. The basal Delorme Group onlaps underlying Lower Silurian dolostones with a locally angular unconformity. The Tsetso Formation quartzarenite, a transgressive peritidal sandstone, represent the onset of the Devonian
transgression in the study area and is locally followed by the brecciated dolomudstones and interbedded anhydrites of the Camsell Formation. In the southern Mackenzie Mountains, facies equivalence includes the calcareous Vera, Root River and Cadillac
Conodont material from the Delorme Group and lateral equivalents is rare, especially in the Northern Mackenzie Mountains, and gives a Lochkovian to Pragian (woschmidti to kindlei zones) age estimate. The Delorme Group is separated
from the overlying Bear Rock Assemblage by an abrupt change to clean limestone and dolostone.
In the Bear Rock Assemblage (Bear Rock, Arnica and Landry formations), the crystalline banded Arnica dolostone and the overlying crystalline Landry
limestone pass eastward into the brecciated limestone and dolostone of the Bear Rock Formation and westward in the shaly Road River Group, Funeral Formation or Mount Baird Formation. In the southern Mackenzie Mountains, the calcareous Sombre, Grizzly
Bear and Natla formations can be distinguished as lateral facies of the Arnica Formation. The Bear Rock Assemblage conodont data set allows the identification of the dehiscens to serotinus zones (Emsian) for the Arnica Formation and lateral
equivalents and the costatus to australis zones (Eifelian) for the Landry Formation and lateral equivalents. The subtidal variously argillaceous and richly fossiliferous limestone of the Eifelian Hume Formation has been sampled at four sections.
Graphic correlation on these data provides a high-resolution correlation between the sections, and a conodont range chart that can be subdivided into local faunal units linked to the australis to ensensis zones (Uyeno et al., 2017). This allows
correlation with sections in the Headless and Nahanni formations in the southern Mackenzie Mountains. The drowning of the Hume platform is marked by the onset of the black shales of the Bluefish Member (Hare Indian Formation) in the ensensis Zone.
|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.