First published: 20 January 2020
Last modified:
DISCLAIMER: This English version is translated from the original French. In case of any discrepancy, the French version shall prevail.
| Author(s): | Dimroth, 1968 |
| Age: | Paleoproterozoic |
| Stratotype: | The type locality is downstream of the High Falls of the Swampy Bay River. Other representative outcrops occur SE of Uvé Pond and west of the southern bay of Otelnuk Lake (NTS sheet 24C01). |
| Type area: | Otelnuk Lake area (NTS sheet 24C01) |
| Geological province: | Churchill Province |
| Geological subdivision: | New Quebec Orogen (Labrador Trough) |
| Lithology: | Mudstone, chert |
| Category: | Lithostratigraphic |
| Rank: | Formation |
| Status: | Formal |
| Use: | Active |
Background
The name Hautes-Chutes Formation was introduced by Dimroth (1968) to refer to a graphitic slate layer located at the High Falls of the Swampy Bay River in the Otelnuk Lake area. Rocks of this unit were mainly mapped by Dimroth (1965, 1969, 1972, 1978). They were later studied by Kish and Tremblay-Clark (1978) and by Kish (1994) to assess their mineral potential.
Description
The Hautes-Chutes Formation consists mainly of black graphitic mudstone or black graphitic slate, and a 4 to 10 m thick layer of black graphitic chert at the base (Dimroth, 1978). The rocks are fine grained, have sharp cleavage and break up into thin chips. Bedding is not visible on outcrops or has not been preserved. Slates contain horizons that are very enriched in graphite and, locally, in pyrite. Some beds may contain up to 20% pyrite porphyroblasts (Dimroth, 1965, 1969, 1978). These pyrite-bearing layers can be recognized by their rusty patina (Kish, 1994). Gossans cap the formation east of Véronot Lake (sheet 24C01) and north of Pistolet Lake (sheet 24C02). The latter are probably overlying pyrite-rich slates. They are formed of slate chips cemented by iron oxides (Dimroth, 1969, 1978). In thin sections, thin tabular bedding a few tenths of a millimetre thick is locally visible when rocks are not too metamorphosed and deformed (Dimroth, 1978). Kish (1994) determined that organic matter in the formation is composed of relict kerogen grains surrounded by spongy, amorphous graphite. Hautes-Chutes sedimentary rocks are thought to have been deposited in shallow water, in an environment where organic matter production was high and coarse detrital material deposition was very low. Pyrite observed in black sediments is thought to be of diagenetic origin (Dimroth, 1978). Kish (1994) mentioned that the Hautes-Chutes Formation locally contains anomalous gold values.
Thickness and distribution
The Hautes-Chutes Formation belongs to the Cambrien and Schefferville lithotectonic zones, as defined by Clark and Wares (2004). It occurs west of Otelnuk Lake, downstream of the High Falls on the Swampy Bay River, and east and west of South Bay in eastern Chakonipau Lake (sheet 24C01). Additional outcrops of this formation have been observed at several locations south, west and north of Castignon Lake (sheets 24C02, 24C07 and 24C10) (Dimroth, 1969, 1978). The thickness ranges from 100 to 305 m (Dimroth, 1965, 1969).
Dating
None.
Stratigraphic Relationship(s)
The Hautes-Chutes Formation is Paleoproterozoic in age. Slate deposition occurred between 2169 ±4 and 2142 +4/-2 Ma, i.e. during the depositional period of first-cycle sedimentary rocks (T. Krogh and B. Dressler, unpublished data cited in Clark, 1984, page 4; Rohon et al., 1993; Clark and Wares, 2004).
The Hautes-Chutes Formation is the basal unit of the Swampy Bay Group sequence. It conformably overlies the Uvé Formation of the Pistolet Group (Dimroth, 1969, 1978). Contacts between these formations are visible east and west of the South Bay in the eastern part of Chakonipau Lake (Dimroth, 1978). The upper contact with the overlying Savigny Formation is not visible. The relationship between the two formations at the Swampy Bay River High Falls suggests a gradual contact (Dimroth, 1969, 1978). According to Dressler (1979), the Hautes-Chutes, Savigny and Otelnuc formations may be partly equivalent.
Paleontology
Does not apply.
References
Publications Available Through SIGÉOM Examine
CLARK, T. 1984. GÉOLOGIE DE LA RÉGION DU LAC CAMBRIEN – TERRITOIRE DU NOUVEAU-QUÉBEC; MINISTÈRE DE L’ÉNERGIE ET DES RESSOURCES; QUÉBEC. ET 83-02, 77 pages and 1 plan.
CLARK, T., WARES, R. 2004. SYNTHÈSE LITHOTECTONIQUE ET MÉTALLOGÉNIQUE DE L’OROGÈNE DU NOUVEAU-QUÉBEC (FOSSE DU LABRADOR); MINISTÈRE DE L’ÉNERGIE ET DES RESSOURCES; QUÉBEC. MM 2004-01, 182 pages and 1 plan.
DIMROTH, E. 1965. GÉOLOGIE DE LA RÉGION DU LAC OTELNUK, TERRITOIRE DU NOUVEAU-QUÉBEC. MINISTÈRE DES RICHESSES NATURELLES, QUÉBEC. RP 532, 30 pages, 1 plan.
DIMROTH, E. 1969. GÉOLOGIE DE LA RÉGION DU LAC CASTIGNON, TERRITOIRE DU NOUVEAU-QUÉBEC. MINISTÈRE DES RICHESSES NATURELLES, QUÉBEC. RP 571, 62 pages, 7 plans.
DIMROTH, E. 1972. STRATIGRAPHY OF PART OF THE CENTRAL LABRADOR TROUGH. MINISTÈRE DE L’ÉNERGIE ET DES RESSOURCES, QUÉBEC. DP 154, 304 pages and 6 plans.
DIMROTH, E. 1978. RÉGION DE LA FOSSE DU LABRADOR ENTRE LES LATITUDES 54°30′ ET 56°30′. MINISTÈRE DE RICHESSES NATURELLES, QUÉBEC. RG 193, 417 pages and 16 plans.
DRESSLER, B. 1979. RÉGION DE LA FOSSE DU LABRADOR (56°30′ – 57°15′). MINISTÈRE DES RICHESSES NATURELLES, QUÉBEC. RG 195, 136 pages, 14 plan.
KISH, L. 1994. SHALES NOIRS DANS LA FOSSE DU LABRADOR, QUÉBEC. MINISTÈRE DES RESSOURCES NATURELLES, QUÉBEC. MB 94-43, 16 pages.
KISH, L., TREMBLAY-CLARK, P. 1978. GÉOCHIMIE ET RADIOACTIVITÉ DANS LA FOSSE DU LABRADOR, 56°00′ – 58°30′. MINISTÈRE DES RICHESSES NATURELLES, QUÉBEC. DPV-567, 73 pages.
Other Publications
DIMROTH, E. 1968. Sedimentary textures, diagenesis, and sedimentary environment of certain Precambrian ironstones. Neues Jahrbuch fuer Geologie und Palitontologie, Abhandlungen; Volume 130, pages 247-274.
ROHON, M.-L., VIALETTE, Y., CLARK, T., ROGER, G., OHNENSTETTER, D., VIDAL, P. 1993. Aphebian mafic-ultramafic magmatism in the Labrador Trough (New Quebec): its age and the nature of its mantle source. Canadian Journal of Earth Sciences; volume 30, pages 1582-1593. http://doi.org/10.1139/e93-136
Suggested Citation
Ministère de l’Énergie et des Ressources naturelles (MERN). Hautes-Chutes Formation. Quebec Stratigraphic Lexicon. https://gq.mines.gouv.qc.ca/lexique-stratigraphique/province-de-churchill/formation-des-hautes-chutes_en [accessed on Day Month Year].
Contributors
|
First publication |
Charles St-Hilaire, GIT, M.Sc. charles.st-hilaire@mern.gouv.qc.ca (redaction) Mehdi A. Guemache, P. Geo., Ph.D. (redaction and coordination); Thomas Clark, P. Geo., Ph.D. (critical review); Simon Auclair, P. Geo., M.Sc. (editing); Céline Dupuis, P. Geo., Ph.D. (English version); Ricardo Escobar Moran (HTML editing). |