| Titre | Origin of the Sokoman iron formation, Labrador Trough, Canada |
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| Auteur | Zajac, I S; Peter, J M |
| Source | Canadian Mineralogist vol. 60, 2022 p. 417-431, https://doi.org/10.3749/canmin.2000112 |
| Image |  |
| Année | 2022 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20210149 |
| Éditeur | Association minéralogique du Canada |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.3749/canmin.2000112 |
| Media | papier; en ligne; numérique |
| Formats | pdf |
| Province | Québec; Terre-Neuve-et-Labrador |
| SNRC | 23; 24 |
| Lat/Long OENS | -72.0000 -64.0000 60.0000 52.0000 |
| Sujets | fer; formations ferrifères; historique; silice; Formation de fer de Sokoman; stratigraphie; minéralogie; Protérozoïque |
| Illustrations | cartes de localisation; diagrammes stratigraphiques; photographies; modèles schématiques |
| Programme | Initiative géoscientifique ciblée (IGC-5) Systèmes volcaniques et sédimentaires - systèmes minéralisés de sulfure massif volcanogénique |
| Diffusé | 2022 05 31 |
| Résumé | (disponible en anglais seulement)
The Lower Proterozoic, Lake Superior-type Sokoman Iron Formation of the Labrador Trough is one of the world's largest iron formations. It represents a unique,
major event in the history of the Trough. Originally a largely irregularly bedded, intraclastic, granular, locally oolitic, conglomeratic iron formation, it is highly variable in its stratigraphy, mineralogy, and textures, which are the consequence
of sedimentology, diagenesis, metamorphism, structural deformation, and magmatic overprint. Despite its complexity, the regional characteristics of the iron formation within the 1200 km length of the Labrador Trough indicate three main stratigraphic
units, defined by their dominant iron minerals: the lower and upper parts of the formation are characterized by the abundance of iron silicates and carbonates (silicate-carbonate facies), and the middle part is characterized by the dominance of iron
oxides (oxide facies). The origin of these lithostratigraphic units of the iron formation is attributed to three main sea-level changes which changed the chemistry (oxidation-reduction potential) and the physical energy (wave and current action) of
the sedimentary environment. The vast amount of iron and some of the silica required for deposition of the Sokoman Formation is inferred to be the consequence of intense hydrothermal activity within a major rift created by the eastward extension of
the Labrador Trough ca 1.88 Ga. The hydrothermal fluids venting within the rift saturated the deep and likely anoxic sea of the Trough with ferrous iron and some silica which then upwelled onto its oxygenated shallow waters to deposit the iron
formation. The end of the processes involved in creating the iron formation ca. 1.82 Ga is attributed to the westward contraction of the Trough induced by the Hudsonian (Trans-Hudson) orogeny, which closed the iron- and silica-generating rift and at
the same time ended all magmatic activities and related sedimentation coeval with the deposition of the iron formation. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Cet article de revue présente les caractéristiques géologiques de la formation ferrifère de Sokoman, principale source de production de minerai
de fer au Canada. |
| GEOSCAN ID | 328564 |
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