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| Aubinadong Formation | |
|---|---|
| Name | Aubinadong Formation |
| Period | Paleoproterozoic |
| Type | Geological formation |
| Unitof | Espanola Terrane |
| Underlies | Varies |
| Overlies | Varies |
| Thickness | Variable |
| Lithology | Metasedimentary rocks, iron formation, chert, quartzite |
| Namedfor | Aubinadong River |
| Region | Ontario, Canada |
Aubinadong Formation The Aubinadong Formation is a Paleoproterozoic metasedimentary unit within the Canadian Shield of Ontario associated with the Huronian Supergroup and exposed in the Sudbury Basin region and adjacent greenstone belts. It is notable for its banded iron formation, cherts, and quartzites and for its regional significance to studies of the Great Oxidation Event, Stratiform ironstone deposition, and the tectonometamorphic evolution of the Superior Province and Grenville Province margins. Researchers from institutions such as the Geological Survey of Canada, Ontario Geological Survey, and universities like the University of Toronto and Queen's University at Kingston have mapped and analyzed the unit in context with adjacent formations such as the Penokean orogeny-related sequences.
The Aubinadong Formation occurs within the Paleoproterozoic stratigraphy of the Huronian Supergroup and is spatially linked to the Esker Belt and intervening metavolcanic and metasedimentary successions studied in the context of the Trans-Hudson Orogen and the Kenoran orogeny. Regional mapping shows structural relationships with the Sudbury Igneous Complex, fault systems like the Matachewan Fault Zone, and metamorphic overprints correlated with episodes recorded in the Canadian Shield. The unit contributes to reconstructions of basin evolution contemporaneous with the Gunflint Iron Formation-age successions and provides markers used in regional cross-sections by teams from the Geological Society of America and the International Union of Geological Sciences.
Lithologically the formation comprises banded iron formation, chert, jasper, hematite-rich layers, and interbedded quartzite and metapelite, with local carbonate-rich horizons comparable to parts of the Animikie Group and the Huronian Supergroup subdivisions. Stratigraphic relationships show lateral facies changes documented in mapping by the Ontario Geological Survey and comparative sections constructed by researchers affiliated with the University of Ottawa and the Royal Ontario Museum. The succession displays primary sedimentary structures preserved in chert and silica-rich layers analogous to sequences described in the Belt Supergroup and correlated with iron-formation-bearing packages in the Lorrain Formation.
Fossil preservation in the Aubinadong Formation is limited due to regional metamorphism, but the unit is considered within the broader Paleoproterozoic record that includes microfossil and stromatolitic evidence reported from contemporaneous units such as the Gunflint Iron Formation, Transvaal Supergroup, and the Barberton Greenstone Belt. Studies drawing on paleobiological methods from the Field Museum and Smithsonian Institution have compared silica-rich horizons to microbial mat textures documented at localities like the Apex Chert and assessments by paleontologists at McMaster University and University of British Columbia.
Interpretations propose deposition in shallow marine to restricted basin settings influenced by hydrothermal input and periodic oxygenation events tied to the Great Oxidation Event and basin redox fluctuations evidenced in iron precipitation patterns similar to those in the Iron Ore Group and Banded iron formation occurrences worldwide. Sedimentological and geochemical analyses by teams from McGill University and the Geological Survey of Canada invoke models involving storm-affected shelves, submarine exhalative systems, and syn-depositional fault control analogous to depositional frameworks used for the Pilbara craton and Hamersley Basin.
Radiometric constraints and regional correlation place the Aubinadong Formation within the Paleoproterozoic, broadly coeval with the time interval of ca. 2.5–1.8 Ga emphasized in studies of the Huronian Supergroup, Gunflint Formation, and parts of the Trans-Hudson Orogeny. U–Pb zircon, Re–Os and Sm–Nd isotopic work by scientists at the Geological Survey of Canada, University of Western Ontario, and international collaborators have been used to correlate the unit with iron-rich successions in the South African Transvaal Supergroup and with glacial and post-glacial horizons tied to the Makganyene glaciation and other Paleoproterozoic events.
The formation hosts iron-rich horizons that have been evaluated for iron ore potential in regional resource assessments conducted by the Ontario Ministry of Northern Development and Mines and prospecting interests including companies formerly listed on the Toronto Stock Exchange and the TSX Venture Exchange. Silica and chert layers have been examined for industrial minerals and as potential sources for metallurgical silica analogous to commodities exploited in the Pilbara and Minnesota Iron Range. Exploration campaigns coordinated with regulatory frameworks from the Canadian Environmental Assessment Agency and provincial agencies have considered mineral tenure, heritage impacts involving Indigenous communities such as the Anishinaabe and Nipissing First Nation, and infrastructure implications tied to rail corridors serving the Greater Sudbury area.
Initial descriptions and mapping were undertaken by field geologists associated with the Geological Survey of Canada and early provincial surveys in the mid-20th century, with formal nomenclature refined in successive bulletins by the Ontario Geological Survey and academic monographs from researchers at Queen's University at Kingston and McMaster University. Conferences of the Canadian Geophysical Union and publications in journals such as the Canadian Journal of Earth Sciences and the Precambrian Research series have chronicled evolving interpretations, while collaborative projects with international partners from institutions like the University of Johannesburg and the Australian National University have placed the formation in global Paleoproterozoic context.
Category:Geologic formations of Ontario Category:Paleoproterozoic formations