| Titre | Subsurface sedimentology, ichnology and sequence stratigraphy of Cambrian Mount Clark and Mount Cap formations beneath the Colville Hills, Northwest Territories |
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| Auteur | Sommers, M J; Gingras, M K; MacNaughton, R B ; Fallas, K M |
| Source | Core Conference 2019, proceedings; 2019 p. 1-6  Accès
ouvert |
| Liens | Online - En ligne
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| Image |  |
| Année | 2019 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20190098 |
| Éditeur | Canadian Society of Petroleum Geologists |
| Réunion | Core Conference 2019; Calgary, AB; CA; mai 16-17, 2019 |
| Document | site Web |
| Lang. | anglais |
| Media | en ligne; numérique |
| Formats | pdf |
| Province | Territoires du Nord-Ouest |
| SNRC | 95J; 95K; 95M; 95N; 95O; 96B; 96C; 96D; 96E; 96F; 96G; 96J; 96K; 96L; 96M; 96N; 96O; 97A; 97B; 106A; 106G; 106H; 106I; 106J; 106O; 106P; 107A |
| Région | Colville Hills |
| Lat/Long OENS | -132.0000 -122.0000 69.0000 62.0000 |
| Sujets | stratigraphie systématique; analyses stratigraphiques; ichnologie; empreintes fossiles; géologie du substratum rocheux; lithologie; roches sédimentaires; grès; schistes; carbonates; mudstones; dolomies;
puits; échantillons carrotés; analyses de faciès; structures sédimentaires; Formation de Mount Clark ; Formation de Mount Cap ; Puit Tweed Lake A-67 ; stratigraphie; sédimentologie; paléontologie; Sciences et technologie; Nature et environnement;
Phanérozoïque; Paléozoïque; Cambrien |
| Illustrations | cartes de localisation; tableaux |
| Programme | GEM2 : La géocartographie de l'énergie et des minéraux Géo-transect Shield à Selwyn, sous-projet Mackenzie-Selwyn du corridor de
Mackenzie |
| Diffusé | 2019 05 01 |
| Résumé | (disponible en anglais seulement)
The Series 2 and Miaolingian (Lower and Middle) Cambrian succession in the Colville Hills region, Northwest Territories consists (ascending order) of the Mount
Clark, Mount Cap and Saline River formations, all of which were deposited in an epicontinental basin, herein named the Colville Basin. Mount Clark Formation consists of a sandstone-dominated succession with a prominent shale package near the middle
of the unit. Mount Cap Formation is divided into an informal lower member (shale with prominent dolostone and sandy dolostone markers) and upper member (shale with carbonates). A high-resolution study of all ten available industry cores used process
sedimentology and ichnology to delineate fifteen lithofacies in the Mount Clark and Mount Cap Formations: six sandstone dominated; three mudstone dominated; four heterolithic sandstone and mudstone; and one each of dolostone and glaucony. The facies
can be grouped into four facies associations (FAs). FA1 consists of sandstone with well-preserved, wave-formed sedimentary structures, recording deposition in storm-influenced shoreface settings. Bioturbation is minimal to absent, suggesting that
wave energy exerted a major stress on burrowing organisms. FA2 consists of sandstone in which bioturbation is strongly developed and trace-fossil diversity is high, including local development of Skolithos 'pipe-rock', but with poor preservation of
physical sedimentary structures. Deposition thus is interpreted to have been in fairweather shoreface settings. FA3 contains varying volumes of mudstone, generally recording deposition in more offshore settings. Absence of bioturbation in some
successions of FA3 may reflection stresses due to seawater chemistry, possibly low oxygen levels. FA4 encompasses bioturbated, locally sandy carbonates deposited in relatively shallow water. Core and wireline log data permitted delineation of three
transgressive-regressive (T-R) sequences in the Mount Clark and lower Mount Cap formations, which can be traced over an area of approximately 300,000 km2. The base of the Cambrian is a regional-scale disconformity and sequence boundary (sub-Cambrian
unconformity). Based on archival trilobite collections, T-R Sequence 1 is of Bonnia-Olenellus Zone age or older, but unlikely to be older than early Cambrian. T-R Sequence 2 contains Bonnia-Olenellus Zone trilobites in its uppermost part, though its
base may be older. The base of T-R Sequence 3 is within the Bonnia-Olenellus Zone, and the lowest trilobites of the Glossopleura Zone are present just above its top, although fossil collections from much of the sequence are equivocal as to age. The
upper member of the Mount Cap Formation has not been subdivided into sequences, but contains a prominent maximum flooding surface near its base and is capped by an unconformity at the base of the Saline River Formation. The upper member is mainly of
Glossopleura Zone age. As noted by previous workers, syndepositional extension during deposition of the Mount Cap Formation was pronounced in the Mackenzie Trough but more subdued beneath the Colville Hills. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Au début et au milieu du Cambrien, la région située sous les plaines intérieures septentrionales du Canada était recouverte d'une mer ancienne.
Aujourd'hui, les roches que cette mer a déposées sont enfouies et contiennent des accumulations de gaz naturel et de pétrole. Le présent article tente de reconstituer, à partir de l'analyse de carottes de forage et de diagraphies géophysiques de
puits réalisés par l'industrie, les débuts de l'histoire du bassin dans lequel s'est formée cette mer ancienne. Les dépôts les plus anciens sont principalement constitués de grès (formation de Mount Clark), tandis que les plus récents contiennent
surtout des mudstones et quelques roches carbonatées (formation de Mount Cap). Nous présentons trois « successions » de roches qui ont enregistré les hausses et les baisses du niveau de la mer. En combinaison avec la détermination de l'âge par des
trilobites précédemment documentés, ces trois successions permettent également de corréler spatialement ces roches dans l'ensemble du Nord canadien, et ce, avec une plus grande précision qu'auparavant. Le bassin ancien dans lequel ces roches se sont
accumulées n'a pas encore été nommé. Il est suggéré de l'appeler Bassin Colville, d'après les collines Colville et la collectivité de Colville Lake qui aujourd'hui s'élèvent à peu près en son centre. |
| GEOSCAN ID | 314757 |
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