Fractional crystallization: separates ore and non-ore minerals according to their crystallization temperature. As early crystallizing minerals form, they incorporate certain elements, some of which are metals. ... Chromite and magnetite are ore minerals that form in this way. Liquid immiscibility: sulfide ores containing copper, nickel or ...
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Fractional crystallization during the evolution of mid-ocean ridge basalts can explain why they are so different in iron isotopic composition from abyssal peridotites, according to chemical ...
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The Qianshan pluton in the eastern North China Craton consists of A-type biotite granites and coeval MMEs, and previously-published field observations and whole-rock geochemical data show that it was formed by magma mixing and fractional crystallization during early Cretaceous (Yang et al., 2006).Here, we integrate in situ trace element and Sr isotopic …
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Compositional variability in lithophile and chalcophile elements records sulfide fractional crystallization across MSS and ISS magnetites and sulfide interaction with silicate minerals (reactional magnetite) and fluids (hydrothermal magnetite).
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Compositional differences between MSS and ISS magnetite record fractional crystallization of sulfide liquid. Particularly, the lower V content of ISS magnetite relative to that of MSS magnetite suggests an increase in fO 2 during fractionation of the sulfide liquid. Accordingly, this results in greater diffusion of oxygen between the sulfide ...
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Clinopyroxene, amphibole, biotite, apatite, and magnetite have low Zr contents that cannot reduce the melt Zr during fractional crystallization. Chevkinite and titanite have high Zr contents but low Zr/Hf ratios that cannot cause a decrease in Zr/Hf of the melt ( Fig. 5 ).
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Magnetite is common in various magmatic and hydrothermal ore deposit types, and its trace element geochemistry has become increasingly used in ore genesis studies and mineral exploration. While fractional crystallization has been shown to influence the chemistry of igneous magnetite, the extent to which this process regulates the trace element composition of …
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Fractional crystallization, the opposite of partial melting, ... In calc-alkaline magmas, the iron is oxidized, leading to crystallization of magnetite. Consequently, when mafic minerals crystallize, iron is removed from the magma as fast as magnesium and the melt's Fe:Mg ratio remains about constant during differentiation. In tholeiitic ...
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δ 49 Ti of mineral separates and bulk rocks from the Kos volcano-plutonic system. Analyzed mineral phases: magnetite, olivine, biotite, plagioclase, quartz • A first δ 49 Ti bulk rock trend is explained by fractional crystallization.. A second δ 49 Ti bulk rock trend is explained by a magma mixing processes.. Δ 49 Ti between different mineral phases agree to a first order with ...
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Request PDF | Magnetite Chemistry by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry Records Sulfide Fractional Crystallization in Massive Nickel-Copper-Platinum Group Element Ores ...
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This indicates that detectable Mg isotopic fractionation occurred in MgO-poor samples, probably through fractional crystallization of Mg-bearing Fe–Ti oxides. Further Mg isotopic analysis of Fe–Ti oxide phenocrysts (titanomagnetite) in the evolved samples reveals that titanomagnetite has remarkably higher δ 26 Mg value (+0.15‰ to +0.52 ...
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The evolution of oxygen fugacity during crystallization of the Layered Series is poorly constrained, but it was estimated to be close to the FMQ (Fayalite–Magnetite–Quartz) buffer at the appearance of Fe–Ti oxide minerals (Namur et al., 2010). Here, we assumed the system is open to oxygen and buffered at FMQ throughout the considered ...
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While magnetitites contain foliated plagioclase grains in non-cotectic proportions, the magnetite is characterized by a regular upwards-depletion of Cr which is best explained by …
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Here we address the origins of the Main Magnetite Layer, a globally important resource of Fe-Ti-V-rich magnetite. Previous models of in situ fractional magnetite …
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Such a transition cannot be explained by the fractional crystallization of Cr-magnetite, which would result in a continuous decrease rather than a sharp gap of Cr 2 O 3 of magnetite (e.g., Kruger and Latypov, 2020).
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The Mg isotopic variations in different types of rocks are closely related to fractional crystallization and accumulation of different proportions of oxides vs. silicates. Chromite crystallization and accumulation is the most important factor in controlling Mg isotope fractionation during the formation of the Xiadong intrusion.
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The results demonstrate that fractional crystallization of magnetite markedly reduces V/Sc values of the residual melt. Furthermore, magnesium number (Mg#) at the onset of magnetite fractionation is strongly positively correlated with fO of the equilibrium magma. Based on this, the oxidation of arc magmas from different crustal thicknesses can ...
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The in situ crystallization model reproduces the mineral trace element patterns of the phlogopite wehrlites when fractional crystallization is the dominant mechanism. The average clinopyroxene REE pattern of MO-10-392 is best fit when F = 63.5 % and L = 0.5 % (Fig. 9 a), MO-10-323 when F = 67.3 % and L = 0.6 %, and MO-11-8 when F = 72 % and L ...
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The Fe-oxides magnetite and ilmenite, and in particular chromite, are useful petrogenetic indicators in igneous rocks and provide valuable information on the composition of the parental magma, temperature, oxygen fugacity, melt-rock interaction, fractional crystallization trends of the silicate melt and post-cumulus processes (Buddington and ...
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Relatively large amounts of magnetite occur in Unit III of the Xinjie intrusion. The mechanism to accumulate so much magnetite is enigmatic. Normal fractional crystallization is used to explain the accumulation of abundant magnetite and the formation of Fe-Ti-rich ore layers in Panzhihua (Pang et al., 2009). But this model is not applicable for ...
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Previously published measured vertical profiles (1–4) of Cr contents in magnetite from the MML compared with results of our models conducted using parameters summarized in Table 1.Solid lines in a–c show trends resulting from various fractional crystallization models chosen to match the main parts of the profiles as well as possible; these fail to match the upper and basal parts …
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Columbite, apatite and magnetite in massive Fe-REE-Nb ore and dolomite-type Nb-REE-(Fe) ore occur at same mineral generation, both having magmatic origins. Pyrochlore from aegirine-type Fe-REE-Nb ore also showsclose genetic relationship with apatite, which is formed by fractional crystallization during the magmatic stage of carbonatite.
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The Baima layered intrusion is located in the central part of the Emeishan Large Igneous Province (ELIP). The N–S striking intrusion is ~ 24 km long and ~ 2 km thick and dips to the west.Based on variations in modal proportions and cumulus mineral assemblages, the intrusion from the base to the top is simply subdivided into a lower zone (LZ) with most of the …
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The Red Hill suite displays a decrease in δ 57 Fe after Fe–Ti oxide saturation, which was explained by the fractional crystallization of near-pure magnetite (X′usp ≈ 0.05) from the magmatic system (Sossi et al. 2012).
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Favorable conditions for the precipitation of large quantities of Ti magnetite were created by a lengthy period of fractional crystallization that resulted in the concentration of large amounts of Fe, Ti, and V in the residual magma.2. ... Crystallization of Ti magnetite is controlled by the Fe 2 O 3 /FeO ratio of the liquid and is a function ...
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Binary plots of Cr versus Ti and V of the type 2 Cr-spinel from the Zhdanov deposit. The fractional crystallization trend was defined by Dare et al. (2012) according to magnetite from sulfide ores from Ni-Cu-(PGE) deposits in Sudbury Complex. The "Primitive Fe-rich" indicates magnetite from sulfide ores with a (Pt + Pd)/IPGE ratio less than ...
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Injections of this melt form magnetite orebodies by crystallization of magnetite (mt; gray) and diopside (di; green). Fractional crystallization drives the melt toward sulfate (anhydrite [anhy]; pink)–dominated composition, leading to formation of sulfate-rich veins and alteration. asl—above sea level; Fm—Formation.
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The complex formed by fractional crystallization of clinopyroxene, amphibole, magnetite, and apatite from a hydrous parent magma. Early removal of clinopyroxene caused H 2 O enrichment in evolved residual magmas and crystallization of magnetite and amphibole, forming low-grade mineralization with Ti-V-poor magnetite in hornblendite.
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fractional crystallization of magnetite from a homogeneous body of melt containing 57 ppm 118. Cr 3,25, with f O 2 between zero and one log unit below the quartz-fayalite-magnetite oxygen 119.
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It also outlines a general multistage crystallization pathway involving a series of intermediates and explains how various strategies (e.g., pH and additives) modulate magnetite properties by influencing its intermediates …
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Previous studies have shown a rapid cooling and a high H2O content of the Jiaodong mafic magma. Combine with the garnet-spinel transition zone of mantle lithosphere and magnetite observed in petrography, we tend to propose that the variation in oxygen fugacity of mafic magma were caused by magnetite-spinel fractional crystallization at depth.
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Magnetite in Ni–Cu deposits is compositionally different from magnetite in layered intrusions (such as the Bushveld Complex) because sulfide and silicate liquids evolve differently during fractional crystallization (Dare et al., 2014).
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In our models, magnetite is collected as discrete crystals to form an orthocumulate-textured mush during fractional crystallization; reversals of Cr gradients in more complex profiles are …
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Magnetite chemistry by laser ablation-inductively coupled plasma-mass spectrometry records sulfide fractional crystallization in massive nickel-copper-platinum group element ores from the …
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