| Titre | Middle-Upper Devonian conodont faunas and biostratigraphy of the Horn River Group in the northern Mackenzie Mountains and Plain (NWT, Canada) |
| |
| Auteur | Gouwy, S A |
| Source | Geoconvention 2020, abstract archive; 2020 p. 1  Accès
ouvert |
| Liens | Online - En ligne
|
| Image |  |
| Année | 2020 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20200407 |
| Réunion | Geoconvention 2020; Septembre 13-15, 2020 |
| Document | site Web |
| Lang. | anglais |
| Media | en ligne; numérique |
| Formats | pdf |
| Province | Territoires du Nord-Ouest |
| SNRC | 96C; 96D; 96E; 96F |
| Région | Mackenzie Mountains; Norman Wells; Powell Creek |
| Lat/Long OENS | -128.0000 -125.0000 65.5000 64.5000 |
| Sujets | Dévonien supérieur; Dévonien moyen; biostratigraphie; micropaléontologie; microfossiles; conodontes; faunes; antecedents de sedimentation; paléoenvironnement; fossiles stratigraphiques; corrélations
stratigraphiques; bassins sédimentaires; zones fossilifères; Groupe d'Horn River ; Formation d'Hare Indian ; Membre de Bluefish ; Formation de Canol ; Formation de Ramparts ; Membre de Kee Scarp ; paléontologie; stratigraphie; Nature et
environnement; Sciences et technologie; Phanérozoïque; Paléozoïque; Dévonien |
| Programme | GEM2 : La géocartographie de l'énergie et des minéraux Corridor de Mackenzie |
| Diffusé | 2020 09 01 |
| Résumé | (Sommaire disponible en anglais seulement)
The Horn River Group (Middle and Upper Devonian) of the northern Mackenzie Mountains and Mackenzie Plain has been a topic of conodont biostratigraphic
research since the early 1970's. The drowning of the lower Middle Devonian shelf with deposition of organic-rich black shales (Bluefish Member of the Hare Indian Formation, Canol Formation) and the development of platform and reefal facies (Ramparts
Formation) produced diverse paleoenvironments for the study of conodont fauna. Conodonts are important index fossils for regional and interregional correlation in the Devonian and a detailed biostratigraphic framework is essential for understanding
facies relationships within the Group, for the regional study of the Horn River Group and for correlation with other sedimentary basins.
This study is based on new sampling during several field campaigns (2016-2019; within NRCan's GEM II and GNES
projects), combined with historical GSC conodont collections from the 1970's and 1980's. Conodonts from 16 sections, situated along the northern Mackenzie Mountain front and in the Mackenzie Plain near the town of Norman Wells, were studied for
biostratigraphy and faunal diversity. The best-studied section in the study area, Powell Creek, is chosen as conodont biostratigraphic reference section to which other sections are compared and correlated.
In this new framework, most of the
Givetian and several of the Frasnian conodont zones are now recognized. The base of the Horn River Group (base of the Hare Indian Formation) is situated within the ensensis Zone. The oldest Ramparts deposits are found in the Middle varcus Zone; its
Kee Scarp Member starts in the disparilis Zone and possibly reaches up into the Frasnian Zone 4. The base of the Canol Formation is of Givetian age (hermanni Zone), in the western part of the study area where the Ramparts Formation is not present,
but is of latest Givetian age (norrisi Zone) and early Frasnian age above the Ramparts Plateau and Key Scarp members respectively. Conodonts from the top of the Canol Formation suggest a late Frasnian age. Abundance of data depends largely on the
lithology, favoring calcareous deposits for sample processing (Ramparts Formation limestone versus Hare Indian and Canol shales with some calcareous beds). Conodont faunas are reasonably diverse in the Hare Indian Formation and increase slightly in
diversity and abundance in the Ramparts Formation. This decreases again in the Canol Formation. Using this biostratigraphic framework, multiple anoxic events within the Horn River Group can tentatively be correlated with black-shale events in other
sedimentary basins. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Les conodontes sont un groupe éteint de chordés marins sans mâchoire dont les éléments de l'appareil d'alimentation ou les dents sont des
microfossiles communs dans les sédiments marins (Cambrien à Trias, 541Ma-201Ma). L'évolution de ces éléments constitue la base d'un cadre temporel relatif (biostratigraphie) dans lequel se positionnent les sédiments marins d'un bassin. La
biostratigraphie des conodontes permet une comparaison / corrélation de différents affleurements du même temps dans un bassin sédimentaire et une corrélation avec d'autres bassins. Un cadre temporel relatif est créé à base de l'étude des éléments de
conodontes du Groupe de Horn River du Dévonien Moyen-Supérieur (393Ma - 359Ma) dans les Mackenzie Mountains et Mackenzie Plain. La plupart des zones clés du cadre peuvent être reconnues et permettent une corrélation régionale et mondiale. |
| GEOSCAN ID | 327220 |
|
|