Fault slickensides (Biwabik Iron-Formation, Paleoproterozoic, ~1.878 Ga; Thunderbird Mine, Mesabi Iron Range, Minnesota, USA) 1 : 無料・フリー素材/写真
Fault slickensides (Biwabik Iron-Formation, Paleoproterozoic, ~1.878 Ga; Thunderbird Mine, Mesabi Iron Range, Minnesota, USA) 1 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Fault slickensides on slate from the Precambrian of Minnesota, USA.This rock is from a Minnesota iron mine that is targeting banded iron formations, or BIFs, which are unusual, dense, marine sedimentary rocks consisting of alternating layers of iron-rich oxides and iron-rich silicates. Most BIFs are Proterozoic in age, although some are Late Archean. They do not form in today's oceans - they're an example of an “extinct” rock type. Many specific varieties of iron formation are known. The most attractive type is jaspilite, which is a reddish & silvery gray banded rock consisting of hematite, red chert (“jasper”), and specular hematite or magnetite. Most BIFs have been subjected to one or more orogenic (mountain-building) events, resulting in folding and/or metamorphism. BIFs are known from around the world, but some of the most famous & extensive deposits are found in the vicinity of North America’s Lake Superior Basin. Many BIFs have economic concentrations of iron and are mined as iron ores.The lineations that extend from the top to the lower left are "slickensides", which were formed by fault movement.Stratigraphy: lower slaty member, Biwabik Iron-Formation, middle Animikie Group, upper Paleoproterozoic, ~1.878 GaLocality: Thunderbird Mine/Auburn Mine - open-pit mine complex on the western side of Rt. 53, south of the town of Virginia & north of the town of Eveleth, Mesabi Iron Range, central St. Louis County, northeastern Minnesota, USA |
| 撮影日 | 2016-12-10 19:30:27 |
| 撮影者 | James St. John |
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