File:Magnetite-rich banded iron-formation (BIF) (Michipicoten Iron-Formation, Neoarchean, 2696-2749 Ma; outcrop above Route 17 roadcut east of Bridget Lake, south of Wawa, Ontario, Canada) 30 (48070028687).jpg

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Banded iron-formation in the Precambrian of Ontario, Canada.

This is an exposure of glacially eroded, Archean-aged, folded, magnetite-rich banded iron formation (BIF). An adjacent roadcut shows these BIFs perched atop basement rocks. Occasional patches of shiny glacial polish are present.

I'm not absolutely sure about the formal stratigraphic name of this unit at this site, but it appears to be the Michipicoten Iron-Formation (Neoarchean, 2.696 to 2.749 billion years old).

The exposure is anthropogenic - the original vegetation and soil was stripped away after visible gold was discovered in a shear zone/fault zone nearby. The inactive Ranson Gold Mine occurs near here, which exploited the same gold occurrence that was found in the stripped area. The basement rocks below the BIFs are part of the Bridget Lake Stock, which consists of “quartz feldspar porphyry”. The Bridget Lake Stock is supposedly the source of the gold mineralization.

Locality: Antoine Lake West Outcrop - glacially eroded exposure on the southern side of Route 17, just west of Antoine Lake, southeast of Bridget Lake, south-southwest of the town of Wawa, Michipicoten Greenstone Belt, Ontario, southeastern Canada (47° 53’ 44.43” North latitude, 84° 50’ 46.62” West longitude)
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Source Magnetite-rich banded iron-formation (BIF) (Michipicoten Iron-Formation, Neoarchean, 2696-2749 Ma; outcrop above Route 17 roadcut east of Bridget Lake, south of Wawa, Ontario, Canada) 30
Author James St. John

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This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/48070028687 (archive). It was reviewed on 10 October 2019 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0.

10 October 2019

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current00:56, 10 October 2019Thumbnail for version as of 00:56, 10 October 20194,288 × 2,848 (8.66 MB)Ser Amantio di Nicolao (talk | contribs)Transferred from Flickr via #flickr2commons

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