An Experimental Study of the Influence of Oxygen Fugacity on Fe-Ti Oxide Stability, Phase Relations, and Mineral--Melt Equilibria in Ferro-Basaltic Systems

Toplis, Michael J.; Carroll, M.

doi:10.1093/petrology/36.5.1137

Cited by 533 publications

(332 citation statements)

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“…Since the work of Buddington and Lindsley (1964) experimental studies have confirmed the strong influence of oxygen fugacity on the stability fields of Fe-Ti oxides (Hill and Roeder, 1973;Grove and Baker, 1984;Juster et al, 1989;Snyder et al, 1993;Toplis and Carroll, 1995). These one-atmosphere experiments on ferrobasalts show that the stability field of magnetite expands with increasing fO 2 .…”

Section: Fo 2 and Parental Magma Compositionmentioning

confidence: 85%

“…Consequently, at high fO 2 , the appearance of magnetite would precede that of ilmenite. However, Toplis and Carroll (1995) have shown that fO 2 only affects the stability field of magnetite whereas the saturation point of ilmenite is controlled by the TiO 2 content of the melt. Consequently, the larger stability field of ilmenite alone under reduced conditions is a consequence of magnetite destabilization, and thus iron-enrichment in the melt.…”

Section: Fo 2 and Parental Magma Compositionmentioning

confidence: 99%

“…Since Buddington and lindsley (1964), many experimental studies have clearly shown that the primary compositions of coexisting Fe-Ti oxides depend on temperature and oxygen fugacity. Another factor, the TiO 2 content of parental melts, may control the stability of (hemo-)ilmenite and (Ti-)magnetite (Toplis and Carroll, 1995). This is critical for mining considerations, since Ti in magnetite has a low value and a limited market.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Fe–Ti–V–P ore deposits associated with Proterozoic massif-type anorthosites and related rocks

Charlier

Namur

Bolle

et al. 2015

Earth-Science Reviews

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a b s t r a c t a r t i c l e i n f oMagmatic rocks containing economic concentrations of iron, titanium, vanadium and phosphorous are commonly associated with massif-type anorthosites and related rocks. This rock association is part of the anorthositemangerite-charnockite-(rapakivi-)granite suites that are restricted to the Proterozoic. Understanding the geochemistry and emplacement mechanisms of ilmenite, magnetite and apatite ore deposits is crucial for exploration, efficient mining operations and ore processing. This review discusses the controlling factors on the grade of an ore, its mineralogy, and its major and trace element distribution. We present petrogenetic models of currently mined deposits (Lac Tio, Tellnes, Damiao) and discuss the characteristics of minor ore bodies from anorthosite provinces worldwide (Grenville, North China Craton, East European Craton, Rogaland, Laramie). Models of formation of anorthosite and related rocks are presented, as well as the nature of the possible parental magmas of the suite. A mineralogical classification of Fe-Ti ores is proposed: (1) Gabbro-noritic ilmenite ore ± apatite ± magnetite; (2) Ti-magnetite-dominated ore; (3) Nelsonite (Fe-Ti oxides + apatite); and (4) Rutile-ilmenite ore. The stability of ilmenite and magnetite is then critically reviewed and the influence of various factors, particularly oxygen fugacity and crystallization pressure, is examined. We discuss liquidus compositions of Fe-Ti oxides and the behavior of important trace elements such as Cr and V, both of which are sensitive to fO 2 variations. Postcumulus evolution of both oxides can occur due to re-equilibration with trapped liquid, re-equilibration with ferromagnesian silicates, exsolution, oxidation, reaction between ilmenite and magnetite, and metamorphic overprinting. These various processes are described and their effects on the oxide geochemistry are emphasized. Several potential ore-forming processes have been invoked and can explain the formation of huge concentration of ilmenite, ±magnetite, ±apatite. Fractional crystallization can be combined with crystal sorting and plagioclase buoyancy to produce relative enrichment of dense ore minerals. Silicate liquid immiscibility can segregate conjugate Si-rich and Fe-rich melts, the latter being enriched in Fe-Ti-P. Magma mixing can produce hybrid magmas located in a single-phase field of the phase diagram and precipitate a pure ilmenite cumulate. Alternative processes are also described, such as ejection of Fe-Ti-enriched residual melts by filter-pressing and compaction, solidstate remobilization of ilmenite in veins, and hydrothermal transport of Fe and Ti from the host anorthosite followed by concentration in veins and lenticular ore bodies. The magnetic properties of Fe-Ti ore deposits present contrasting signatures, depending on whether the natural remanent magnetization is dominated by hemo-ilmenite or multi-domain magnetite. Micro-and macro-scale deformation features of ore rocks are intimately correlated with magma emplacement, and...

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Section: Fo 2 and Parental Magma Compositionmentioning

confidence: 85%

Section: Fo 2 and Parental Magma Compositionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fe–Ti–V–P ore deposits associated with Proterozoic massif-type anorthosites and related rocks

Charlier

Namur

Bolle

et al. 2015

Earth-Science Reviews

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“…Liquidus temperatures were calculated using the relation between the melt MgO content and the temperature experimentally observed by Toplis and Carroll (1995), and the liquid FeO/Fe 2 O 3 ratios were estimated by assuming fO 2 conditions along the FMQ buffer (Namur et al 2010). Liquid density increased from 2.70 to 2.75 during crystallization of po-C rocks and then decreased continuously down to 2.63 g/cm 3 due to fractionation of Fe-Ti oxide-bearing cumulates ( Fig.…”

Section: Residual Liquid Versus Stratigraphic Height and Physical Promentioning

confidence: 99%

Efficiency of compaction and compositional convection during mafic crystal mush solidification: the Sept Iles layered intrusion, Canada

Namur

Charlier

2012

Contrib Mineral Petrol

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Adcumulate formation in mafic layered intrusions is attributed either to gravity-driven compaction, which expels the intercumulus melt out of the crystal matrix, or to compositional convection, which maintains the intercumulus liquid at a constant composition through liquid exchange with the main magma body. These processes are length-scale and time-scale dependent, and application of experimentally derived theoretical formulations to magma chambers is not straightforward. New data from the Sept Iles layered intrusion are presented and constrain the relative efficiency of these processes during solidification of the mafic crystal mush. Troctolites with meso-to ortho-cumulate texture are stratigraphically followed by Fe-Ti oxide-bearing gabbros with adcumulate texture. Calculations of intercumulus liquid fractions based on whole-rock P, Zr, V and Cr contents and detailed plagioclase compositional profiles show that both compaction and compositional convection operate, but their efficiency changes with liquid differentiation. Before saturation of Fe-Ti oxides in the intercumulus liquid, convection is not active due to the stable liquid density distribution within the crystal mush. At this stage, compaction and minor intercumulus liquid crystallization reduce the porosity to 30%. The velocity of liquid expulsion is then too slow compared with the rate of crystal accumulation. Compositional convection starts at Fe-Ti oxide-saturation in the pore melt due to its decreasing density. This process occurs together with crystallization of the intercumulus melt until the residual porosity is less than 10%. Compositional convection is evidenced by external plagioclase rims buffered at An 61 owing to continuous exchange between the intercumulus melt and the main liquid body. The change from a channel flow regime that dominates in troctolites to a porous flow regime in gabbros results from the increasing efficiency of compaction with differentiation due to higher density contrast between the cumulus crystal matrix and the equilibrium melts and to the bottom-up decreasing rate of crystal accumulation in the magma chamber.

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“…Accordingly, another necessary prerequisite for the evolution to high Fe-Ti contents is that a low oxygen fugacity (fO 2 ) throughout magmatic evolution delays the saturation of Ti-magnetite in the melt and allows Fe-Ti enrichment in the residual magma, as pointed out by many researchers (Brooks and Nielsen, 1978;Wilson et al, 1985;James et al, 1987;Brooks et al, 1991;Wiebe, 1997;Williams, 1998;Jang et al, 2001;Rutherford et al, 2006). Experimental studies have established that ilmenite saturation will result in an enrichment in Fe in the residual liquid with low silica at low fO 2 , and may even reach a maximum of ∼18 wt% FeOt (Toplis and Carroll, 1995). In fact, a pronounced negative correlation between FeOt and TiO 2 and Mg number (Fig.…”

Section: Mechanism Of Fe-ti Enrichmentmentioning

confidence: 99%

Mesoproterozoic high Fe–Ti mafic magmatism in western Shandong, North China Craton: Petrogenesis and implications for the final breakup of the Columbia supercontinent

Peng

Wilde

et al. 2013

Precambrian Research

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An Experimental Study of the Influence of Oxygen Fugacity on Fe-Ti Oxide Stability, Phase Relations, and Mineral--Melt Equilibria in Ferro-Basaltic Systems

Cited by 533 publications

References 0 publications

Fe–Ti–V–P ore deposits associated with Proterozoic massif-type anorthosites and related rocks

Fe–Ti–V–P ore deposits associated with Proterozoic massif-type anorthosites and related rocks

Efficiency of compaction and compositional convection during mafic crystal mush solidification: the Sept Iles layered intrusion, Canada

Mesoproterozoic high Fe–Ti mafic magmatism in western Shandong, North China Craton: Petrogenesis and implications for the final breakup of the Columbia supercontinent

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