banded iron formations
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Banded iron-formations (BIFs) occur in the Precambrian geologic record over a wide time span. Beginning at 3.8 Ga (Isua, West Greenland), they are part of Archean cratons and range in age from about 3.5 until 2.5 Ga. Their overall volume reaches a maximum at about 2.5 Ga (iron-formations in the Hamersley Basin of Western …
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Permissions. Banded iron formations (BIFs) have been at the center of many debates in geology, especially regarding the early (i.e., Archean and Paleoproterozoic) Earth and its surface environments. BIFs are chemical sedimentary rocks that have an …
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And there are banded iron formations in Australia and South America and Africa. And that middle phase is really the source of most of the world's iron. CATHY WURZER: So we talked about heat and ...
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The chemical evolution of Precambrian seawater: evidence from REEs in banded iron formations. Geochimica et Cosmochimica Acta 54, 2965–2977 (1990). Article ADS CAS Google Scholar
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Precambrian Banded Iron Formations (BIFs) (Fig. 1) are marine chemical sediments consisting of alternating iron oxide-rich and silica-rich bands (Trendall and Blockley 1970).BIFs can be found as massive iron ore deposits in Australia, South Africa, Canada, China, Brazil, Ukraine, and a number of other locations, with occurences noted …
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Banded iron formations are critical to track changes in Archaean to Palaeoproterozoic ocean chemistry, with deposition triggered by water column iron oxidation. Recently, however, it was suggested ...
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Banded iron formations (BIFs) comprise the largest iron resource on Earth. They formed throughout much of the Precambrian (∼3800–543 Ma), reaching their …
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Oxidation of iron-rich rock is known to generate H2 in oceanic as well as in continental domains. Here we tested the possibility of H2 generation as the result of weathering of banded iron formations (BIF). The BIF constitute more than 60% of global iron ore reserves with low Fe3+/Fetot and total Fe ranging from 20 to 40 wt% and are …
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In 1992 a new theory was proposed on the origin of banded iron formations. In the Snowball Earth hypothesis, a severe ice age from 750 million to 580 million years ago totally or nearly depleted the oxygen in the atmosphere. Dissolved iron then accumulated in the oxygen-starved oceans, possibly from undersea hydrothermal vents.
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Banded iron formations (BIFs) host the world's largest iron ore deposits, and they formed predominantly through the deposition of ferric iron [Fe(III)] from ferruginous oceans during the Archean Eon (1, 2).Most models for BIF deposition invoke photosynthesis in the oxidation of ferrous iron from seawater to induce its subsequent precipitation and …
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Banded iron formations (BIF) comprise the largest iron resource on Earth. They formed throughout much of the Precambrian (∼3,800–545 Ma), reaching their maximum abundance between 2,700 and 2,400 Ma years ago. Numerous examples can be found on almost every continent and their deposition has been linked to significant compositional changes in ...
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Banded iron formations (BIF) comprise the largest iron resource on Earth. They formed throughout much of the Precambrian (∼3,800–545 Ma), reaching their maximum …
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Among the latter is the wide variety of varve-like repetitive laminae, known as microbands. Banded Iron Formations. Figure 3. Thin sections of banded iron formation, Mamatwan Manganese Mine, Hotazel, northern Cape Province, South Africa. Samples were taken from a depth of 83.4 m ( a) and 87.5 m ( b ). Full size image.
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Sedimentary iron deposits, from which almost all iron is obtained, can therefore be viewed as one of the world's great mineral treasures. There are two major types of deposit. The first, and by far the most important, is banded iron formations (BIFs), so called because they are finely layered alternations of cherty silica and an iron mineral ...
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The Biology Behind Banded Iron Formations. A long-enduring puzzle in the evolution of the early Earth concerns when and to what extent surface oxidation occurred. One important piece of this puzzle is determining when oxygen production began, and how early oxygen was consumed by reduced species, such as iron (Fe (II)), in the …
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Banded iron formations (BIFs) are distinctive Precambrian chemical sedimentary deposits with alternating iron and silica-rich bands precipitated from ferruginous oceans 14.
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For example, iron can be carried in solution in a non-oxygenated environment. However, when iron combines with free oxygen, it creates a solid precipitate to make minerals like hematite (iron oxide). This is the reason large deposits of iron known as banded iron formations are common during this time, ending around 2 billion years ago [ 48 ].
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Iron formations are similar to ironstones but are mainly Precambrian (ironstones are Phanerozoic). Iron formations generally contain abundant chert and are often well banded with bands ranging from centimeters to meters thick. The bands consist of alternating iron- and chert-rich layers. Figure 8.57 photo shows an example of iron …
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The banded iron formations of the Hamersley Province in the Pilbara region of Western Australia, are the thickest and most extensive rocks of this type in the world. It is estimated that after they were originally deposited, about 2470 to 2450 million years ago, they covered some 150 000 km2 and contained about 300 trillion tonnes of iron. The ...
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Banded Iron Formation, or BIF, is the name given to these banded and kink-folded alternating layers of iron oxide (hematite and magnetite) and microcrystalline silica (red and brown chert and golden-brown tiger eye). They used to be iron-rich and silica-rich sediments on the ancient sea floor about 2.5 billion years ago.
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Banded Iron Formation, or BIF, is the name given to these banded and kink-folded alternating layers of iron oxide (hematite and magnetite) and microcrystalline silica (red and brown chert and golden …
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Banded iron-formations (BIFs) are marine chemical sedimentary rocks composed of siliceous and ferric materials, usually with typical thin layers or sheet structures. BIFs not only record a wealth of information about the state and evolution of the lithosphere, atmosphere, hydrosphere, and biosphere but also host the majority of the …
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Banded iron formations (also known as banded ironstone formations or BIFs) are distinctive units of sedimentary rock that are almost always of Precambrian age. A typical BIF consists of repeated, thin layers (a few millimeters to a few centimeters in thickness) of silver to black iron oxides, either.
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Banded iron formations are chemical sediments precipitated directly from ancient seawater rich in dissolved iron. Metabolic actions of microorganisms, including photosynthesis, are thought to have facilitated the precipitation of the minerals, which formed layer upon layer over time along with chert (microcrystalline silicon dioxide). ...
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Study with Quizlet and memorize flashcards containing terms like The following images depict some of the events leading to the formation of Earth. Drag and drop the correct descriptions for each of the events., Refer to the accompanying pictures, which include some of the important events leading to the formation of Earth. Rank the images …
به خواندن ادامه دهیدBanded iron formations are chemical sediments precipitated directly from ancient seawater rich in dissolved iron. Metabolic actions of microorganisms, including photosynthesis, are thought to have ...
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It is generally believed that banded iron formations (BIFs), the bulk of which was formed in the late Archaean/Palaeoproterozoic marine basins, occurred in stratified water columns deep in the ...
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Banded Iron Formations The Rise and Fall and Rise and Fall and Rise and Fall and Rise… of the Cyanobactia Empire. Banded Iron Formation. Beautiful striped rocks dating billions of years ago tell story of the dramatic risings and fallings of the cyanobacteria. Two billion years ago, the Earth had no plants and no animals.
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Banded iron formation (BIF) is dominant in Archean to earliest Paleoproterozoic successions, whereas granular iron formation (GIF) is much more common in Paleoproterozoic successions. Secular changes in the style of iron-formation deposition, identified more than 20 years ago, have been linked to diverse environmental …
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Banded iron formations are predominantly Precambrian in age; most are 1.8 to 2.2 billion years old; none are younger than Cambrian age. The most important iron-bearing minerals in iron formations are hematite, magnetite, and greenalite. These deposits constitute the world's major source of iron ore.
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Banded iron formations are worldwide layered sedimentary deposits rich in iron that range in age from 1.5 to 3.8 billion years old, the age of the earliest known rocks. …
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Banded iron formations were a prevalent feature of marine sedimentation ~3.8–1.8 billion years ago and they provide key evidence for ferruginous oceans. The disappearance of banded iron ...
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Precambrian banded iron formations are found in a few other places on the earth's surface, principally Labrador, Quebec, Manchuria, India, Brazil and the Krivoy Rog area of Russia, but until recently such deposits have been little utilized for iron ore production excepting the United States. The iron formation and associated rocks of Michigan were
به خواندن ادامه دهیدA nearly 3-billion-year-old banded iron formation from Canada shows that the atmosphere and ocean once had no oxygen. Photosynthetic organisms were making oxygen, but it reacted with the iron dissolved in seawater to …
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Iron formations are similar to ironstones but are mainly Precambrian (ironstones are Phanerozoic). Iron formations generally contain abundant chert and are …
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Banded iron formations are critical to our current economy as they are by far the biggest source of economic iron deposits. A BIF is hard and heavy sedimentary stone. The bands are composed of …
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For instance, banded iron formations appear in Carajas, Brazil; Lake Superior, Canada; Hamersley Basin, Western Australia; regions in northern China; and the Mesabi Iron Range in Minnesota.
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One way of tracing the Fe redox cycle through time has been studying banded iron formations (BIF s). These rock formations likely formed when Fe(II)-rich …
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banded-iron formation (BIF), chemically precipitated sediment, typically thin bedded or laminated, consisting of 15 percent or more iron of …
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Image copyright of WA Museum. Most of the major iron deposits worldwide occur in rocks called banded iron formations (or BIFs for short), which are finely layered sedimentary rocks composed of alternating chert (a form of …
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