High-pressure phase transitions of natural chromitite from …
ResultIt has been shown that in the natural chromite + SiO 2 system, chromite decomposes into an mLd-phase (modified ludwigite phase, with an idealized composition of Mg 2 Cr 2 O 5 ) + eskolaite at 15 GPa (Wu etal., 2016). In another report on the FeCr 2 O 4 system, mLd + eskolaite was observed for pressures of …
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Genesis of "silicate exsolution lamellae" in
Result1. Introduction. Chromite has high resistance to alteration and weathering and, together with its inclusions, is widely used as a crucial petrogenetic indicator for the origin of mafic-ultramafic rocks (e.g., Kamenetsky et al., 2001; Pagé and Barnes, 2009).The only known sources of chrome are chromitites from …
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Extremely large fractionation of Li isotopes in a chromitite …
ResultLithium isotopic compositions of olivine. All of the olivine grains analyzed in this study, regardless of their host lithology, have low Li contents (~0.1 to 0.9 ppm).
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High-pressure phase transitions of natural chromitite from …
ResultThe stability of anhydrous phase B, Mg14Si5O24, has been determined in the pressure range of 14–21 GPa and the temperature range of 1100–1700 °C with both normal and reversal experiments ...
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SiO2 solubility in rutile at high temperature and high pressure
ResultSilicon-bearing rutile has been found in chromitite from the Luobusa () ophiolite, Tibet. However, the extent of SiO2 solubility in rutile and the nature of its origin are still unclear. At high pressure, SiO2 takes a rutile structure with Si in 6-fold coordination. Thus, high pressures may enhance its solubility in rutile …
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(PDF) Peritectic crystal entrainment during partial melting in …
ResultPDF | On Jan 1, 2023, Tahnee Otto and others published Peritectic crystal entrainment during partial melting in the mantle: Importance for the formation of layered ultramafic complexes ...
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Massive chromitite layers of the Bushveld Complex, South …
ResultThis model is complicated by melt convection and pressure-dependent phase transition temperature. Approximate analytical solutions to this nonlinear moving-boundary problem are constructed. Namely,...
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Chromitites in ophiolites: How, where, when, why? Part II.
ResultThis implies that each chromitite body integrates melts formed by partial melting of very large volumes of mantle peridotite (up to ~ 30 × 10 3 m 3 for the 5 × 0.3 m high-Cr chromitite of the Ojén massif; González-Jiménez et al., 2013a). These calculations suggest that the formation of a chromitite body …
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Conversion of low-pressure chromitites to ultrahigh-pressure
ResultThe recycled UHP chromitites can coexist with young low-P chromitites at a spreading center because the upper mantle beneath the spreading center can be the very place in that the low-P chromitite forms via peridotite/melt interaction (e.g., Arai and Yurimoto, 1994) and the deep recycled (UHP) chromitites appears via …
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Ultra-high pressure inclusion in Archean ophiolitic podiform chromitite …
ResultUltra-high pressure TiO 2 II identified in Archean ophiolitic podiform chromite mélange.. Crustal minerals subducted to > 270 km at 2.55 Ga, then recycled to surface. • UHP mélange is part of paired metamorphic Central (Taihang) Orogenic Belt of North China. Data shows operation of subduction-related deep …
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Melting Point Definition and List
ResultThe element with the lowest melting point is helium, with a melting point of 0.95 K (−272.20 °C, −457.96 °F) at 2.5 MPa pressure. This is very near absolute zero. The metal with the lowest melting point is mercury, with a melting point of 234.3210 K (−38.8290 °C, −37.8922 °F). Mercury is a liquid at room …
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How Does Pressure Affect Melting Point?
ResultConsequently, higher pressure increases the melting point of these substances. In accordance to Le Chatelier's principle, an increase in pressure counteracts the volume expansion caused by melting, thus, raising the melting point. On the other hand, some substances, like ice, bismuth, and antimony, contract when melted.
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Platinum-bearing chromite layers are caused by pressure …
ResultHere we address the problem by examining the pressure-related changes in the topology of a Mg2SiO4-CaAl2Si2O8-SiO2-MgCr2O4 quaternary …
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Osmium and zinc isotope constraints on the origin of
ResultThe discoveries of ultra-high pressure and super-reducing minerals in the Luobusa ophiolite since the 1980s implied a deep mantle origin of ophiolite and related ... the mineral chemistry of chromites in the YZSZ chromitite generally implies a parental melt of boninitic affinity. The connection of chromite chemistry …
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12.5: Melting, Freezing, and Sublimation
Result(Carbon dioxide can exist as liquid but only under high pressure.) Dry ice has many practical uses, including the long-term preservation of medical samples. Even at temperatures below 0°C, solid H 2 O will slowly sublime. ... The melting point of a solid is the same as the freezing point of the liquid. At that temperature, the solid …
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Melting Point, Freezing Point, Boiling Point
ResultLiquids boil when their vapor pressure is equal to the pressure exerted on the liquid by its surroundings. The normal boiling point of water is 100 o C because this is the temperature at which the …
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2.1: Melting Point Analysis
ResultMelting point (Mp) is a quick and easy analysis that may be used to qualitatively identify relatively pure samples (approximately <10% impurities). It is also possible to use this analysis to quantitatively determine purity. Melting point analysis, as the name suggests, characterizes the melting point, a stable …
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Formation and modification of chromitites in the mantle
ResultA petrologic model for podiform chromitite formation in mantle harzburgite in a simplified system, olivine-quartz-chromite. Modified from Fig. 2 of Arai and Miura (2015). Mantle-derived olivine-chromite saturated melt (A) reacted with orthopyroxene of the harzburgite to form silica-rich melt (B) and dunite.
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Origin of the UG2 chromitite layer, Bushveld Complex
ResultWhere we have studied the sequence in the central sector of the eastern Bushveld, the UG2 chromitite is embedded in a massive, 25 m thick …
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Genesis and high-pressure evolution of the Köyceğiz …
ResultA genetic model or scenario of the formation and evolution of the Köyceğiz chromitites may include: (i) early crystallization of chromitite from boninitic melts derived from a hydrated mantle wedge above a subducting slab and during peridotite-melt reaction (e.g., Robertson, 2002, Uysal et al., 2007, Xiong et al., …
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Formation and modification of chromitites in the mantle
ResultWe present a comprehensive review on podiform chromitite genesis in the mantle. • We confirm the importance of peridotite-magma reaction and …
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Origin of podiform chromitite, a new model based on the …
ResultThe Luobusa ophiolite contains both massive and disseminated chromitite. • High-pressure mineral inclusions are only found in the massive chromitite. ... The low degree of melting, coupled with low degrees of melt extraction, therefore point to a spreading center at amid-ocean ridge (MOR) or in …
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Origin of the UG2 chromitite layer, Bushveld Complex
ResultTherefore, a change in pressure to account for the UG2 chromitite is not consistent with the observations. Addition of water. Nicholson & Mathez proposed that the thin chromitite seams of the Merensky Reef formed at fronts of hydrous interstitial melt migrating through the crystal pile. The notion was based on …
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Does melting point increase with pressure?
ResultThe melting point is that temperature at which a solid is converted into a liquid. The effect of pressure of the melting point of a solid depends on whether it is expanding or contracting on melting. In case of majority of solids, the melting point increases with increase in pressure as the solid itself is usually more dense than the liquid.
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High-pressure experiments provide insights into the
ResultThe compositional diagrams of Al 2 O 3 vs Cr 2 O 3 and FeO + MgO vs Cr 2 O 3 + Al 2 O 3 (Figs. 3 c, d) for the partial melting experiments show that garnet has incorporated the bulk of the Cr (or Cr + Al), while the Cr content in the corresponding melt is very low. For an experiment (R495) conducted at 15 GPa …
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Platinum-bearing chromite layers are caused by pressure
Result64 Altmetric. Metrics. Abstract. Platinum-bearing chromitites in mafic-ultramafic intrusions such as the Bushveld Complex are key repositories of strategically important metals for human society....
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Melting Point And Pressure:5 Facts You Should Know
ResultWe all know that the volume of ice is lower than the volume of ice. Hence the ice occupies less space than the water. There is an inverse relation between the pressure and the melting point of ice which is known to all. So when the pressure increases on the ice,its volume decreases more. Hence the melting …
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Peridotites, chromitites and diamonds in ophiolites
Resulthigh-pressure mineral inclusions, such as microdiamonds, metal alloys, Mn silicates and coesites, in podiform chromitites and other ophiolitic mantle rocks offer evidence of deep and reduced ...
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Knowledge Structure and Frontier Evolution of Research on Chromitite…
ResultFour articles in this interval discussed podiform chromitite containing ultrahigh-pressure minerals, whereas on other article considered the layer of chromitite. Some of the focal points and/or findings presented in these papers have been summarized as follows: diamonds recovered from ophiolite chromitite were …
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Chromitite
ResultUG2 chromitite is known for enrichment of PGEs, and extends for nearly the entire 400 km length of the Eastern and Western limbs (Mondal et al., 2006).The UG2 horizon represents typically fine-grained massive and stratiforn chromite mineralization having a sharp contact with anorthosite (Fig. 3.5).It is the world's …
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