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49-606: The Phosphoria includes phosphorite beds that are an important source of phosphorus . Many of its shales are rich in organic matter and are petroleum source rocks , and some of its dolomites include petroleum reservoirs . The Phosphoria Formation was deposited under marine conditions in a foreland basin located between the Paleozoic continental margin and the North American cratonic shelf . The upwelling of cold, nutrient-rich marine water at that time stimulated

98-460: A fertilizer in certain soil types and countries, although it has many drawbacks. According to the report it may have higher sustainability compared to more concentrated fertilizers because of reduced manufacturing costs and the possibility of local procurement of the refined ore. Rare earth elements are being found within phosphorites. With increasing demand from modern technology a different method of finding rare earth elements, independent of China,

147-414: A hard, fissile, metamorphic rock known as slate . With continued increase in metamorphic grade the sequence is phyllite , then schist and finally gneiss . Shale is the most common source rock for hydrocarbons ( natural gas and petroleum ). The lack of coarse sediments in most shale beds reflects the absence of strong currents in the waters of the depositional basin. These might have oxygenated

196-1201: Is accompanied by telogenesis , the third and final stage of diagenesis. As erosion reduces the depth of burial, renewed exposure to meteoric water produces additional changes to the shale, such as dissolution of some of the cement to produce secondary porosity . Pyrite may be oxidized to produce gypsum . Black shales are dark, as a result of being especially rich in unoxidized carbon . Common in some Paleozoic and Mesozoic strata , black shales were deposited in anoxic , reducing environments, such as in stagnant water columns. Some black shales contain abundant heavy metals such as molybdenum , uranium , vanadium , and zinc . The enriched values are of controversial origin, having been alternatively attributed to input from hydrothermal fluids during or after sedimentation or to slow accumulation from sea water over long periods of sedimentation. Fossils , animal tracks or burrows and even raindrop impressions are sometimes preserved on shale bedding surfaces. Shales may also contain concretions consisting of pyrite, apatite , or various carbonate minerals. Shales that are subject to heat and pressure of metamorphism alter into

245-486: Is because of the constant stream of phosphate brought from the large, deep ocean reservoir (see below). This cycle allows continuous growth of organisms. Supratidal zones: Supratidal environments are part of the tidal flat system where the presence of strong wave activity is non-existent. Tidal flat systems are created along open coasts and relatively low wave energy environments. They can also develop on high energy coasts behind barrier islands where they are sheltered from

294-622: Is becoming increasingly important. With yields greater than those from deposits in China, phosphorites offer a new resource located within the U.S. that would likely lead to independence from influence of countries outside of the U.S. Shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g., kaolin , Al 2 Si 2 O 5 ( OH ) 4 ) and tiny fragments ( silt -sized particles) of other minerals, especially quartz and calcite . Shale

343-420: Is characterized by its tendency to split into thin layers ( laminae ) less than one centimeter in thickness. This property is called fissility . Shale is the most common sedimentary rock. The term shale is sometimes applied more broadly, as essentially a synonym for mudrock , rather than in the narrower sense of clay-rich fissile mudrock. Shale typically exhibits varying degrees of fissility. Because of

392-719: Is commonly subdivided, from the top downward, as follows: The Phosphoria is underlain by the Pennsylvanian -Permian Casper Formation or, depending on the location, by the Park City Formation or the Tensleep Sandstone , and it is overlain by the Triassic Dinwoody Formation . The upper boundary is placed at the top of the uppermost phosphorite bed and below the tan calcareous siltstone of Dinwoody formation. The lower boundary

441-638: Is composed of about 58% clay minerals, 28% quartz, 6% feldspar , 5% carbonate minerals, and 2% iron oxides . Most of the quartz is detrital (part of the original sediments that formed the shale) rather than authigenic (crystallized within the shale after deposition). Shales and other mudrocks contain roughly 95 percent of the organic matter in all sedimentary rocks. However, this amounts to less than one percent by mass in an average shale. Black shales, which form in anoxic conditions, contain reduced free carbon along with ferrous iron (Fe ) and sulfur (S ). Amorphous iron sulfide , along with carbon, produce

490-430: Is evidence that shale acts as a semipermeable medium, allowing water to pass through while retaining dissolved salts. The fine particles that compose shale can remain suspended in water long after the larger particles of sand have been deposited. As a result, shales are typically deposited in very slow moving water and are often found in lakes and lagoonal deposits, in river deltas , on floodplains and offshore below

539-719: Is intertongued with carbonate rocks of the Park City Formation and redbed sandstones of the Chugwater Formation of Permian to Triassic age. The Phosphoria units extend into the Wind River Mountains and pinch out in the Green Mountains to the east. Fossils recovered from the Phosphoria Formation include brachiopods , sponge spicules , crinoid stems , conodont elements , and fish scales and bones. Most "tooth whorls" of

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588-469: Is mainly on the ocean floor. Phosphorus accumulation occurs from atmospheric precipitation, dust, glacial runoff, cosmic activity, underground hydrothermal volcanic activity, and deposition of organic material. The primary inflow of dissolved phosphorus is from continental weathering, brought out by rivers to the ocean. It is then processed by both micro- and macro-organisms. Diatomaceous plankton, phytoplankton, and zooplankton process and dissolve phosphorus in

637-547: Is marked by a thin phosphorite that contains abundant fish scales and bones. The formation reaches its greatest thickness in the Sublett Range in the Paleozoic cordilleran structural basin of southern Idaho. Within the basin the formation consists of a basal phosphorite overlain by a thick sequence of chert and cherty sandstone . To the east in western Wyoming the Phosphoria gradually decreases in thickness and

686-528: Is mined and beneficiated into rock phosphate. Beneficiation of phosphate ore is a process which includes washing, flotation and calcining. Froth flotation is used to concentrate the mined ore to rock phosphate. The mined ore is crushed and washed, creating a slurry, this ore slurry is then treated with fatty acids to cause calcium phosphate to become hydrophobic . This rock phosphate is then either solubilized to produce wet-process phosphoric acid , or smelted to produce elemental phosphorus . Phosphoric acid

735-455: Is more likely to form nonfissile mudstone than shale. On the other hand, black shales often have very pronounced fissility ( paper shales ) due to binding of hydrocarbon molecules to the faces of the clay particles, which weakens the binding between particles. Lithification follows closely on compaction, as increased temperatures at depth hasten deposition of cement that binds the grains together. Pressure solution contributes to cementing, as

784-412: Is reacted with phosphate rock to produce the fertilizer triple superphosphate or with anhydrous ammonia to produce the ammonium phosphate fertilizers. Elemental phosphorus is the base for furnace-grade phosphoric acid, phosphorus pentasulfide, phosphorus pentoxide , and phosphorus trichloride . Approximately 90% of rock phosphate production is used for fertilizer and animal feed supplements and

833-452: Is reduced. In addition to this physical compaction, chemical compaction may take place via pressure solution . Points of contact between grains are under the greatest strain, and the strained mineral is more soluble than the rest of the grain. As a result, the contact points are dissolved away, allowing the grains to come into closer contact. It is during compaction that shale develops its fissility, likely through mechanical compaction of

882-812: Is related to strong marine upwelling of sediments. Upwelling is caused by deep water currents that are brought up to coastal surfaces where a large deposition of phosphorites may occur. This type of environment is the main reason why phosphorites are commonly associated with silica and chert. Estuaries are also known as a phosphorus “trap”. This is because coastal estuaries contain a high productivity of phosphorus from marsh grass and benthic algae which allow an equilibrium exchange between living and dead organisms. Deposits which contain phosphate in quantity and concentration which are economic to mine as ore for their phosphate content are not particularly common. The two main sources for phosphate are guano , formed from bird or bat droppings, and rocks containing concentrations of

931-558: The Earth's crust . Limestones and mudstones are common phosphate-bearing rocks. Phosphate-rich sedimentary rocks can occur in dark brown to black beds, ranging from centimeter-sized laminae to beds that are several meters thick. Although these thick beds can exist, they are rarely only composed of phosphatic sedimentary rocks. Phosphatic sedimentary rocks are commonly accompanied by or interbedded with shales , cherts , limestone, dolomites and sometimes sandstone . These layers contain

980-399: The U.S. Gulf Coast . As sediments continue to accumulate, the older, more deeply buried sediments begin to undergo diagenesis . This mostly consists of compaction and lithification of the clay and silt particles. Early stages of diagenesis, described as eogenesis , take place at shallow depths (a few tens of meters) and are characterized by bioturbation and mineralogical changes in

1029-669: The wave base . Thick deposits of shale are found near ancient continental margins and foreland basins . Some of the most widespread shale formations were deposited by epicontinental seas . Black shales are common in Cretaceous strata on the margins of the Atlantic Ocean , where they were deposited in fault -bounded silled basins associated with the opening of the Atlantic during the breakup of Pangaea . These basins were anoxic, in part because of restricted circulation in

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1078-454: The Phosphoria phosphorite beds but are not considered to be of economic interest. A vanadium -enriched zone that is present in western Wyoming and southeastern Idaho contains potentially economic concentrations of vanadium in some areas. Petroleum has been produced from some of the dolomites in the Phosphoria Formation, and many of the Phosphoria shales are rich in organic matter and are petroleum source rocks . Phosphate mining in

1127-622: The United States Phosphorite Phosphorite , phosphate rock or rock phosphate is a non- detrital sedimentary rock that contains high amounts of phosphate minerals . The phosphate content of phosphorite (or grade of phosphate rock) varies greatly, from 4% to 20% phosphorus pentoxide (P 2 O 5 ). Marketed phosphate rock is enriched ("beneficiated") to at least 28%, often more than 30% P 2 O 5 . This occurs through washing, screening, de-liming, magnetic separation or flotation. By comparison,

1176-733: The average phosphorus content of sedimentary rocks is less than 0.2%. The phosphate is present as fluorapatite Ca 5 (PO 4 ) 3 F typically in cryptocrystalline masses (grain sizes < 1 μm) referred to as collophane -sedimentary apatite deposits of uncertain origin. It is also present as hydroxyapatite Ca 5 (PO 4 ) 3 OH or Ca 10 (PO 4 ) 6 (OH) 2 , which is often dissolved from vertebrate bones and teeth, whereas fluorapatite can originate from hydrothermal veins . Other sources also include chemically dissolved phosphate minerals from igneous and metamorphic rocks . Phosphorite deposits often occur in extensive layers, which cumulatively cover tens of thousands of square kilometres of

1225-619: The balance for industrial chemicals. In addition, phosphorus from rock phosphate is also used in food preservatives, baking flour, pharmaceuticals, anticorrosion agents, cosmetics, fungicides, insecticides, detergents, ceramics, water treatment and metallurgy. For use in the chemical fertilizer industry, beneficiated rock phosphate must be concentrated to levels of at least 28% phosphorus pentoxide (P 2 O 5 ), although most marketed grades of phosphate rock are 30% or more. It must also have reasonable amounts of calcium carbonate (5%), and <4% combined iron and aluminium oxides. Worldwide,

1274-421: The black coloration. Because amorphous iron sulfide gradually converts to pyrite , which is not an important pigment, young shales may be quite dark from their iron sulfide content, in spite of a modest carbon content (less than 1%), while a black color in an ancient shale indicates a high carbon content. Most shales are marine in origin, and the groundwater in shale formations is often highly saline . There

1323-542: The calcium phosphate mineral, apatite . As of 2006 , the US is the world's leading producer and exporter of phosphate fertilizers, accounting for about 37% of world P 2 O 5 exports. As of December 2018 , the world's total economic demonstrated resource of rock phosphate is 70 gigatonnes , which occurs principally as sedimentary marine phosphorites. As of 2012 , China , the United States and Morocco are

1372-506: The clumps of clay particles produced by flocculation vary in size from a few tens of microns to over 700 microns in diameter. The floccules start out water-rich, but much of the water is expelled from the floccules as the clay minerals bind more tightly together over time (a process called syneresis ). Clay pelletization by organisms that filter feed is important where flocculation is inhibited. Filter feeders produce an estimated 12 metric tons of clay pellets per square kilometer per year along

1421-408: The color of the rock. Red, brown and green colors are indicative of ferric oxide ( hematite – reds), iron hydroxide ( goethite – browns and limonite – yellow), or micaceous minerals ( chlorite , biotite and illite – greens). The color shifts from reddish to greenish as iron in the oxidized ( ferric ) state is converted to iron in the reduced ( ferrous ) state. Black shale results from

1470-492: The enigmatic cartilaginous fish Helicoprion are known from the formation, including the only known specimen with preserved cranial remains. The Early Permian age of the formation is based primarily on conodont biostratigraphy . The Phosphoria phosphorite beds have been mined for phosphorus , which is used primarily for fertilizer production , in southeastern Idaho , northern Utah , western Wyoming , and southwestern Montana . Low concentrations of uranium are present in

1519-436: The growth of plankton and nekton , resulting in the accumulation of organic matter on the sea floor. That, coupled with low rates of clastic and carbonate sedimentation, led to the high phosphate and hydrocarbon content of the formation, as well as elevated levels of cadmium , chromium , copper , fluorine , molybdenum , nickel , rare earth elements , selenium , uranium , vanadium , and zinc . The formation

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1568-408: The high energy wave action. Within the tidal flat system, the supratidal zone lies in a very high tide level. However, it can be flooded by extreme tides and cut across by tidal channels. This is also subaerially exposed, but is flooded twice a month by spring tides. Littoral environments/intertidal zones: Intertidal zones are also part of the tidal flat system. The intertidal zone is located within

1617-418: The mean high and low tide levels. It is subject to tidal shifts, which means that it is subaerially exposed once or twice a day. It is not exposed long enough to support the growth of most vegetation. The zone contains both suspension sedimentation and bed load. Estuarine environments : Estuarine environments, or estuaries, are located at the lower parts of rivers that flow into the open sea. Since they are in

1666-592: The mineral dissolved from strained contact points is redeposited in the unstrained pore spaces. The clay minerals may be altered as well. For example, smectite is altered to illite at temperatures of about 55 to 200 °C (130 to 390 °F), releasing water in the process. Other alteration reactions include the alteration of smectite to chlorite and of kaolinite to illite at temperatures between 120 and 150 °C (250 and 300 °F). Because of these reactions, illite composes 80% of Precambrian shales, versus about 25% of young shales. Unroofing of buried shale

1715-433: The narrow Atlantic, and in part because the very warm Cretaceous seas lacked the circulation of cold bottom water that oxygenates the deep oceans today. Most clay must be deposited as aggregates and floccules, since the settling rate of individual clay particles is extremely slow. Flocculation is very rapid once the clay encounters highly saline sea water. Whereas individual clay particles are less than 4 microns in size,

1764-415: The original open framework of clay particles. The particles become strongly oriented into parallel layers that give the shale its distinctive fabric. Fissility likely develops early in the compaction process, at relatively shallow depth, since fissility does not seem to vary with depth in thick formations. Kaolinite flakes have less tendency to align in parallel layers than other clays, so kaolinite-rich clay

1813-631: The parallel orientation of clay mineral flakes in shale, it breaks into thin layers, often splintery and usually parallel to the otherwise indistinguishable bedding planes . Non-fissile rocks of similar composition and particle size (less than 0.0625 mm) are described as mudstones (1/3 to 2/3 silt particles) or claystones (less than 1/3 silt). Rocks with similar particle sizes but with less clay (greater than 2/3 silt) and therefore grittier are siltstones . Shales are typically gray in color and are composed of clay minerals and quartz grains. The addition of variable amounts of minor constituents alters

1862-817: The presence of greater than one percent carbonaceous material and indicates a reducing environment. Pale blue to blue-green shales typically are rich in carbonate minerals . Clays are the major constituent of shales and other mudrocks. The clay minerals represented are largely kaolinite , montmorillonite and illite. Clay minerals of Late Tertiary mudstones are expandable smectites , whereas in older rocks (especially in mid-to early Paleozoic shales) illites predominate. The transformation of smectite to illite produces silica , sodium , calcium , magnesium , iron and water. These released elements form authigenic quartz , chert , calcite , dolomite , ankerite , hematite and albite , all trace to minor (except quartz) minerals found in shales and other mudrocks. A typical shale

1911-431: The release of phosphorus back into the ocean water. Phosphates are known to be deposited in a wide range of depositional environments . Normally phosphates are deposited in very shallow, near-shore marine or low energy environments. This includes environments such as supratidal zones, littoral or intertidal zones, and most importantly estuarine. Currently, areas of oceanic upwelling cause the formation of phosphates. This

1960-461: The resources of high-grade ore are declining, and use of lower grade ore may become more attractive. Beneficiated rock phosphate is also marketed and accepted as an "organic" alternative to "chemical" phosphate fertilizer which has been further concentrated from it, because it is perceived as being more "natural". According to a report for the FAO, it can be more sustainable to apply rock phosphate as

2009-444: The richest source rocks may contain as much as 40% organic matter. The organic matter in shale is converted over time from the original proteins, polysaccharides , lipids , and other organic molecules to kerogen , which at the higher temperatures found at greater depths of burial is further converted to graphite and petroleum. Before the mid-19th century, the terms slate , shale and schist were not sharply distinguished. In

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2058-887: The same textures and structures as fine-grained limestones and may represent diagenetic replacements of carbonate minerals by phosphates. They also can be composed of peloids, ooids, fossils, and clasts that are made up of apatite. There are some phosphorites that are very small and have no distinctive granular textures. This means that their textures are similar to that of collophane, or fine micrite -like texture. Phosphatic grains may be accompanied by organic matter , clay minerals , silt -sized detrital grains, and pyrite . Peloidal or pelletal phosphorites occur normally; whereas oolitic phosphorites are not common. Phosphorites are known from Proterozoic banded iron formations in Australia , but are more common from Paleozoic and Cenozoic sediments. The Permian Phosphoria Formation of

2107-577: The seaward section of the drowned valley system they receive sediment from both marine and fluvial sources. These contain facies that are affected by tide and wave fluvial processes. An estuary is considered to stretch from the landward limit of tidal facies to the seaward limit of coastal facies. Phosphorites are often deposited in fjords within estuarine environments. These are estuaries with shallow sill constrictions. During Holocene sea-level rise, fjord estuaries formed by drowning of glacially-eroded U-shaped valleys. The most common occurrence of phosphorites

2156-433: The sediments, with only slight compaction. Pyrite may be formed in anoxic mud at this stage of diagenesis. Deeper burial is accompanied by mesogenesis , during which most of the compaction and lithification takes place. As the sediments come under increasing pressure from overlying sediments, sediment grains move into more compact arrangements, ductile grains (such as clay mineral grains) are deformed, and pore space

2205-475: The water. The bones and teeth of certain fish (e.g. anchovies) absorb phosphorus and are later deposited and buried in the ocean sediment . Depending on the pH and salinity levels of the ocean water, organic matter will decay, releasing phosphorus from sediment in shallow basins. Bacteria and enzymes dissolve organic matter on the water–bottom interface, thus returning phosphorus to the beginning of its biogenic cycle. Mineralization of organic matter can also cause

2254-414: The waters and destroyed organic matter before it could accumulate. The absence of carbonate rock in shale beds reflects the absence of organisms that might have secreted carbonate skeletons, also likely due to an anoxic environment. As a result, about 95% of organic matter in sedimentary rocks is found in shales and other mudrocks. Individual shale beds typically have an organic matter content of about 1%, but

2303-680: The western United States represents some 15 million years of sedimentation. It reaches a thickness of 420 metres and covers an area of 350,000 km . Commercially mined phosphorites occur in France , Belgium , Spain , Morocco , Tunisia , Saudi Arabia and Algeria . In the United States phosphorites have been mined in Florida , Tennessee , Wyoming , Utah , Idaho and Kansas . (1) Pristine: Phosphates that are in pristine conditions have not undergone bioturbation . In other words,

2352-520: The word pristine is used when phosphatic sediment, phosphatized stromatolites and phosphate hardgrounds have not been disturbed. (2) Condensed: Phosphatic particles, laminae and beds are considered condensed when they have been concentrated. This is helped by the extracting and reworking processes of phosphatic particles or bioturbation. (3) Allochthonous: Phosphatic particles that were moved by turbulent or gravity-driven flows and deposited by these flows. The heaviest accumulation of phosphorus

2401-680: The world's largest miners of phosphate rock, with a production of 77 megatonnes , 29.4 Mt and 26.8 Mt (including 2.5 Mt in the Sahara of Morocco) respectively in 2012 while global production reached 195 Mt. It is thought that in India there are almost 260 million tons of rock phosphate. Other countries with significant production include Brazil , Russia , Jordan and Tunisia . Historically, large amounts of phosphates were obtained from deposits on small islands such as Christmas Island and Nauru , but these sources are now largely depleted. Phosphate ore

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