ABANDONED UNIT
Publication: 9 March 2020
DISCLAIMER: This English version is translated from the original French. In case of any discrepancy, the French version shall prevail.
| Author(s): | Bérard, 1957, 1965 |
| Age: | Paleoproterozoic |
| Stratotype: | The type locality is west of Abner Lake, now Laumont Lake (58°09′N, 70°08′W, NTS sheet 24L01), where the formation was described by Bérard (1965). |
| Type area: | SW of Ungava Bay, between the Mélèzes River and Feuilles Lake (NTS sheets 24E and 24L) |
| Geological province: | Churchill Province |
| Geological subdivision: | New Quebec Orogen (Labrador Trough) / Mélèzes and Howse lithotectonic zones |
| Lithology: | Dolomitic rocks |
| Category: | Lithostratigraphic |
| Rank: | Formation |
| Status: | Formal |
| Use: | Abandoned |
Background
Bérard (1957) reported the presence of a dolomite and dolomitic sandstone unit north of latitude 58°N, which he named the Abner dolomite. The name comes from Abner Lake, now Laumont Lake (58°09′N, 70°08′W, sheet 24L01). Bérard (1965) later provided a more complete description of the formation, reporting that it extends 81 km from the southern limit of his mapping area (58° N) to Feuilles Lake, where the formation appears to disappear. Clark (1977, 1979) followed this dolomite strip southwards to latitude 57°28′N. In the northern half of the Labrador Trough, other areas where the Abner Formation outcrops extensively were identified by Dressler (1979) and Clark (1977, 1978), for a total outcrop length of ~175 km. The unit is mainly part of the allochthonous Mélèzes Lithotectonic Zone, but is also present in the allochthonous Howse Lithotectonic Zone.
Initially, the Abner Formation was thought to conformably overlie the Chioak Formation, which unconformably overlaid the Wishart and Sokoman formations (Bérard, 1965). Since the latter two were attributed to the second volcano-sedimentary cycle of the Trough, the Abner Formation was thus part of a third volcano-sedimentary cycle, along with the « Upper Iron formation » and the « Larch River slate » (Dimroth, 1970; Dimroth et al., 1970). However, the discovery of a major thrust fault beneath the Abner Formation (Clark, 1979; Budkewitsch, 1986; Goulet, 1986) led to a reinterpretation of its position in the Trough stratigraphic column (Clark and Wares, 2004). Following this reworking of the stratigraphic column, the name Abner Formation was abandoned and the outcrop areas corresponding to this unit were assigned to the Denault Formation (Clark and Wares, 2004).
Reasons for Abandonment
As reported by Clark and Wares (2004, p. 11): « The discovery of a major thrust fault (Garigue Fault) beneath the Abner Formation (Clark, 1979; Budkewitsch, 1986; Goulet, 1986) as well as the results of some U-Pb and Pb-Pb dating have allowed reinterpreting the stratigraphy of the northern orogen (Fournier, 1985; Clark, 1988; Clark and Thorpe, 1990; Machado et al., 1997). The Abner Formation would thus be equivalent to the Denault Formation (Attikamagen Group) of the first cycle, observed in the south of the orogen, as suggested by Hoffman and Grotzinger (1989) and supported by similar carbon isotopic compositions (Melezhik et al., 1997). » As a result, the name Abner Formation has been abandoned in favour of its stratigraphic equivalent, the Denault Formation (Clark and Wares, 2004).
References
Publications Available Through SIGÉOM Examine
BERARD, J. 1957. RAPPORT PRELIMINAIRE SUR LA REGION DU LAC BONES, NOUVEAU-QUEBEC. MRN. RP 342, 10 pages and 1 plan.
BERARD, J. 1957. PRELIMINARY REPORT ON BONES LAKE AREA, NEW QUEBEC. MRN. RP 342(A), 8 pages and 1 plan.
BERARD, J. 1965. REGION DU LAC BERARD, NOUVEAU-QUEBEC. MRN. RG 111, 175 pages and 2 plans.
BERARD, J. 1965. BERARD LAKE AREA, NEW QUEBEC. MRN. RG 111(A), 148 pages and 2 plans.
CLARK, T. 1977. GEOLOGY OF THE FORBES LAKE AREA (NOUVEAU-QUEBEC). MRN. DPV 452, 19 pages and 1 plan.
CLARK, T. 1978. REGION DU LAC HERODIER (NOUVEAU-QUEBEC) – RAPPORT PRELIMINAIRE. MRN. DPV 568, 48 pages and 2 plans.
CLARK, T. 1979. REGION DU LAC NAPIER (NOUVEAU-QUEBEC) – RAPPORT PRELIMINAIRE. MRN. DPV 663, 28 pages and 1 plan.
CLARK, T. 1980. REGION DE LA RIVIERE KOKSOAK (NOUVEAU-QUEBEC) – RAPPORT PRELIMINAIRE. MRN. DPV 781, 24 pages and 1 plan.
CLARK, T. 1987. STRATIGRAPHIE, PETROGRAPHIE ET PETROCHIMIE DE LA FORMATION DE FER DE BABY DANS LA REGION DU LAC HERODIER (FOSSE DU LABRADOR). MRN. ET 87-13, 44 pages.
CLARK, T., WARES, R. 2004. SYNTHESE LITHOTECTONIQUE ET METALLOGENIQUE DE L’OROGENE DU NOUVEAU-QUEBEC (FOSSE DU LABRADOR). MRNFP. MM 2004-01, 182 pages and 1 plan.
DRESSLER, B., CIESIELSKI, A. 1979. REGION DE LA FOSSE DU LABRADOR. MRN. RG 195, 136 pages and 14 plans.
FOURNIER, D. 1985. MINERALISATION DE LA PARTIE ORIENTALE DU GEOSYNCLINAL DU LABRADOR (GROUPE DE LAPORTE). MRN. ET 83-23, 57 pages and 4 plans.
GOULET, N. 1986. ETUDE TECTONIQUE ET STRATIGRAPHIQUE DE LA PARTIE NORD DE LA FOSSE DU LABRADOR – REGION DE LA BAIE AUX FEUILLES ET DU LAC BERARD. MRN. MB 86-27, 22 pages and 6 plans.
Other Publications
BUDKEWITSCH, P. 1986. A structural study of the Chioak-Abner formation contact, northern part of the Labrador Trough, New Quebec. Unpublished M.Sc. thesis, Concordia University, Montréal; 61 pages.
CLARK, T., THORPE, R.I. 1990. Model lead ages from the Labrador Trough and their stratigraphic implications. In: The Early Proterozoic Trans-Hudson Orogen of North America: Lithotectonic Correlations and Evolution (J.F. Lewry, J.F. and M.R. Stauffer, editors). Geological Association of Canada; Special Paper 37, pages 413-432.
DIMROTH, E. 1970. Evolution of the Labrador Geosyncline. Geological Society of America Bulletin; volume 81, pages 2717-2742. doi.org/10.1130/0016-7606(1970)81[2717:EOTLG]2.0.CO;2.
DIMROTH, E., BARAGAR, W.R.A., BERGERON, R., JACKSON, GD. 1970. The filling of the Circum-Ungava geosyncline. In: Symposium on Basins and Geosynclines of the Canadian Shield (A.J. Baer, editor). Geological Survey of Canada; Paper 70-40, pages 45-142. doi.org/10.4095/124922.
HOFFMAN, P., GROTZINGER, J.P. 1989. Abner-Denault reef complex (2.1 Ga), Labrador Trough, N.E. Québec. In: Reefs, Canada and Adjacent Area (H.H.J. Geldsetzer, N.P. James, and GE. Tebbutt, editors). Canadian Society of Petroleum Geologists; Memoir 13, pages 49-54.
MACHADO, N., CLARK, T., DAVID, J., GOULET, N. 1997. U-Pb ages for magmatism and deformation in the New Quebec Orogen. Canadian Journal of Earth Sciences; volume 34, pages 716-723. doi.org/10.1139/e17-058.
MELEZHIK, V.A., FALLICK, A.E., CLARK, T. 1997. Two billion year old isotopically heavy carbon: evidence from the Labrador Trough, Canada. Canadian Journal of Earth Sciences; volume 34, pages 271-285. dx.doi.org/10.1139/e17-025.
Suggested Citation
Ministère de l’Énergie et des Ressources naturelles (MERN). Abner Formation (abandoned). Quebec Stratigraphic Lexicon. https://gq.mines.gouv.qc.ca/lexique-stratigraphique/province-de-churchill/formation-abner_en [accessed on Day Month Year].
Contributors
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First publication |
Thomas Clark, P. Geo., Ph.D. (redaction) Mehdi A. Guemache, P. Geo., Ph.D. (coordination); Charles St-Hilaire, GIT, M.Sc. (critical review); Simon Auclair, P. Geo., M.Sc. (editing); Céline Dupuis, P. Geo., Ph.D. (English version); Nathalie Bouchard (HTML editing). |