| Titre | Reassessment of the Lower Devonian and lower Middle Devonian conodont biostratigraphy in the Northwest Territories, Canada: changes in the time-rock chart for the northern Mackenzie Mountains and adjacent
plains |
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| Auteur | Gouwy, S A ;
Kabanov, P |
| Source | Opening meeting IGCP 652 - program, 'Reading time in Paleozoic sedimentary rocks', Bremen, Germany; 2018 p. 34-35 |
| Image |  |
| Année | 2018 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20180324 |
| Réunion | Opening meeting IGCP 652: Reading time in Paleozoic sedimentary rocks; Bremen; DE; Septembre 18-19, 2018 |
| Document | livre |
| Lang. | anglais |
| Media | papier |
| Formats | pdf |
| Province | Territoires du Nord-Ouest |
| SNRC | 106A; 106B |
| Région | Mackenzie Mountains; Mackenzie Valley |
| Lat/Long OENS | -130.0000 -126.0000 65.0000 64.0000 |
| Sujets | Dévonien moyen; Dévonien inférieur; biostratigraphie; micropaléontologie; microfossiles; conodontes; géologie du substratum rocheux; lithologie; roches sédimentaires; dolomies; brèches; calcaires; grès;
carbonates; évaporites; arénites; mudstones; schistes; discordances; zones fossilifères; Groupe de Delorme ; Formation d'Hume ; Formation de Tsetso ; Formation de Camsell ; Formation de Bear Rock ; Formation d'Arnica ; Formation de Landry ; Formation
d'Hare Indian ; Membre de Bluefish ; stratigraphie; paléontologie; Phanérozoïque; Paléozoïque; Dévonien |
| Programme | GEM2 : La géocartographie de l'énergie et des minéraux Bouclier à Selwyn du corridor de Mackenzie |
| Diffusé | 2018 09 01 |
| Résumé | (disponible en anglais seulement)
The Lower Devonian and lower Middle Devonian in the study area is a succession of dolostone, limestone breccia and massive limestone with minor basal
sandstones. The basal Delorme Group onlaps underlying Lower Silurian dolostones with a locally angular unconformity. The entire Lower Devonian represents a peritidal carbonate platform and evaporate - carbonate alternation occurs in the platform
interior in the eastern part of the study area (Mackenzie Plain). The Lower Devonian peritidal carbonates grade upward into subtidal variously argillaceous and richly fossiliferous limestones of the Eifelian Hume Formation. Based on new field data
and a restudy of GSC-Calgary conodont collections, the time-rock chart for this succession is updated to the current conodont biozonation.
The oldest Devonian deposits, the Delorme Group (Tsetso and Camsell formations) span the interval between
the end of the Silurian and the end of the Lochkovian and overlie the sub-Devonian unconformity. The Tsetso Formation quarzarenite, 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. Conodont material from the Delorme Group is very rare, only one sample from the Camsell Formation provides enough material and indicates a
Lochkovian (eurekaensis to delta zones) age.
The Delorme Group is separated from the overlying Bear Rock Assemblage by an abrupt change from calcareous sandstone to clean limestone and dolostone. The Bear Rock Assemblage comprises the Bear Rock,
Arnica and Landry formations. The crystalline distinctly banded dolostone of the Arnica Formation and the overlying crystalline limestone of the Landry Formation pass laterally into the brecciated limestone and dolostone of the Bear Rock Formation.
Conodont data from Bear Rock Assemblage reconnaissance samples in the Colville Hills assign the strata to the dehiscens to costatus zones (lowermost Emsian to lower Eifelian). Arnica reconnaissance samples from the northern Mackenzie Mountains point
to the lower Emsian (nothoperbonus-inversus zones). Samples from the Landry Formation contain a conodont fauna with a range from the lower Emsian to the lower Eifelian (excavatus to costatus zones).
A new transgressive pulse formed of the lower
unit of the Hume Formation is marked by the deposition of argillaceous limestone and shale (Headless Member) indicating a slight deepening of the environment. The upper unit of the Hume Formation is a fossiliferous thin- to thick- bedded platform
limestone. Four sections were sampled through the Hume Formation in the mountain front of the northern Mackenzie Mountains, allowing a detailed conodont biostratigraphy that indicates a middle to upper Eifelian (australis to ensensis zones) position
for the Formation (Uyeno et al. 2017). 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.
Uyeno, T. T., Pedder, A. E. H. & Uyeno, T.A., 2017. Conodont
biostratigraphy and T-R cycles of the Middle Devonian Hume Formation at Hume River (type locality), northern Mackenzie Mountains, NWT, Canada. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Les présents travaux visent à réévaluer et à mettre à jour l'identification des microfossiles conodontes recueillis dans les années 1970 de
façon à ce que leur désignation soit conforme aux normes actuelles et aux données publiées depuis. Ces travaux permettent un positionnement plus détaillé dans la ligne du temps géologique des formations rocheuses du Dévonien inférieur et du Dévonien
inférieur et moyen que l'on retrouve dans le nord des monts Mackenzie (Territoires du Nord-Ouest), et ils facilitent l'amélioration des mises en corrélation régionales et internationales. |
| GEOSCAN ID | 313287 |
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