Banded iron formations are distinctive units of sedimentary rock that are almost always of Precambrian age.
A typical banded iron formation consists of repeated. Banded iron formations (or BIFs) are a distinctive type of rock often found in ( Precambrian) sedimentary rocks.
BANDED IRON FORMATION
They consist of repeated thin layers of iron oxides. Banded-iron formation (BIF), chemically precipitated sediment, typically thin bedded or laminated, consisting of 15 percent or more iron of sedimentary origin and layers of chert, chalcedony, jasper, or quartz. or banded iron formation (BIF)—regionally extensive, locally.
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Bandediron formations (BIFs) Evidence of Oxygen in Early Atmosphere Learning Geology
Considerable controversy exists over BIF origin, and a number of theories have been proposed. They primarily formed during the Paleoproterozoic era, occurring on continental shelves and can be found around the world. Due to the extreme age of these formations, almost all BIF formations have undergone some faulting, fracturing, folding, compaction, veining, intrusions and metamorphism.
Video: Banded iron formation sedimentary rock Banded Iron Formation
Cambridge University Press. It seems, then, as though in searching for a cause for BIFs we must be looking for an event which could only have happened at in the past.
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|While BIFs have a wide geographical distribution, they are localized in time. Every continent has a BIF formation.
It follows that when organisms arose that produced oxygen, iron dissolved in the oceans would combined with dissolved oxygen to form iron oxides which would then have precipitated out, producing the iron oxides that characterize BIFs.
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Banded iron formation consists of layers of iron oxides (typically either magnetite or hematite) separated by layers of chert (silica-rich sedimentary rock). Banded iron formation (BIF) is both the most easily identifiable of all sedimentary rocks and the one whose origin is most enigmatic. Its flamboyant mesoscale.
Views Read Edit View history. History at your fingertips. Distinctive layered units of iron-rich sedimentary rock that are almost always of Precambrian age.
Oxides Cassiterite tin Chromite chromium Coltan niobium and tantalum Columbite niobium Hematite iron Ilmenite titanium Magnetite iron Pyrolusite manganese Tantalite tantalum Uraninite uranium. What is Life?
Bandediron formation rock
This suggests that sizeable amounts of dissolved oxygen were available to form sediments rich in Fe III.
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|BIFs occur in two forms, Algoma and Superior-type.
The periodic process might have been due to seasonal fluctuations or storm surges or other hypothesis. This article was most recently revised and updated by Amy TikkanenCorrections Manager. This keeps the weight to usable levels and allows BIF to be used as a popular ornamental stone. The shield areas of continents contain the oldest precambrian rocks. For reasons largely unknown, this was a periodic process resulting in the alternating bands of iron oxide and shale.