The origin and evolution of V-rich, magnetite dominated Fe-Ti oxide mineralization; Northwest River Anorthosite, south-central Labrador, Canada

Valvasori, Anthony A.; Hanchar, John M.; Piercey, Stephen J.; Fonkwe, Merline L. D.

doi:10.1007/s00126-019-00892-6

Cited by 7 publications

(3 citation statements)

References 45 publications

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“…The same nanoscale associations may be present in the fine structures enriched in Mg, Ti, V, Cr, and Sc observed on LA-ICP-MS maps (Figure 3). Vanadium enrichment in fine lamellar hematite relative to ilmenite and magnetite was shown at the micron-scale in Fe-Ti mineralization from the Northwest River anorthosite, south-central Labrador, Canada [48]. While this could be the missing evidence in support of the oxidative model shown in [8], the identity of these lamellae as hematite would require crystal structure confirmation.…”

Section: Re-equilibration and Replacement Processes In Panzhihua Fe-tmentioning

confidence: 96%

Nanoscale Study of Titanomagnetite from the Panzhihua Layered Intrusion, Southwest China: Multistage Exsolutions Record Ore Formation

et al. 2019

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Titanomagnetite from Fe-Ti-V ores of the Lanjiahuoshan deposit, Panzhihua layered intrusion, Southwest China, was investigated at the nanoscale. The objectives were to establish the composition of exsolution phases and their mutual relationships in order to evaluate the sequence of exsolution among oxide phases, and assess mechanisms of ore formation during magma emplacement. At the micron-scale, titanomagnetite shows crosscutting sets of exsolutions with ilmenite and Al-Mg-Fe-spinel (pleonaste), as well as overprint, both in terms of phase re-equilibration and remobilization of trace elements. Most complex textures were found in titanomagnetite surrounded by ilmenite and this was selected for high-angle annular dark field scanning transmission electron microscopy (HAADF STEM) imaging and STEM energy-dispersive X-ray spectrometry (EDS) spot analysis and mapping on a thin foil prepared in situ on a focused ion beam scanning electron microscope platform. Titanomagnetite revealed two sequential sets of exsolutions, {111} crosscutting {100}, which are associated with changes in phase speciation and trace element distribution patterns. Qandilite is the dominant spinel phase inside titanomagnetite; magnesioferrite is also identified. In contrast, Fe-poor, Al-rich, Mg-bearing spinel is present within ilmenite outside the grain. Vanadium enrichment in newly-formed magnetite lamellae is clear evidence for trace element remobilization. This V-rich magnetite shows epitaxial relationships with ilmenite at the contact with titanomagnetite. Two-fold super-structuring in ilmenite is evidence for non-redox re-equilibration between titanomagnetite and ilmenite, supporting published experimental data. In contrast, the transformation of cubic Ti-rich spinel into rhombohedral ilmenite imaged at the nanoscale represents the “oxy-exsolution” model of titanomagnetite–ilmenite re-equilibration via formation of a transient ulvöspinel species. Nanoscale disorder is encountered as vacancy layers in Ti-rich spinel, and lower symmetry in the Fe-poor, Al-Mg phase, suggesting that slow cooling rates can preserve small-scale phase equilibration. The cooling history of titanomagnetite ore can be reconstructed as three distinct stages, concordant with published models for the magma plumbing system: equilibrium crystallization of Al-rich, Mg-bearing titanomagnetite from cumulus melts at ~55 km, with initial exsolutions occurring above 800 °C at moderate fO2 conditions (Stage 1); crosscutting {111} exsolutions resulting in formation of qandilite, attributable to temperature increase due to emplacement of another batch of melt affecting the interstitial cumulus during uplift. Formation of 2-fold superstructure ilmenite + V-rich magnetite exsolution pairs representing non-redox equilibration indicates resetting of the cooling path at this stage (Stage 2); and ilmenite formation from pre-existing Ti-rich spinel and ulvöspinel, illustrative of redox-driven cooling paths at <10 km (Stage 3). HAADF STEM provides direct imaging of atomic arrangements, allowing recognition of processes not recognizable at the micron-scale, and can thus be used to constrain exsolution models during ore formation.

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Section: Re-equilibration and Replacement Processes In Panzhihua Fe-tmentioning

confidence: 96%

Nanoscale Study of Titanomagnetite from the Panzhihua Layered Intrusion, Southwest China: Multistage Exsolutions Record Ore Formation

et al. 2019

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“…Magmatic vanadium‐bearing ilmenite–magnetites are one of the primary sources of vanadium and are significant strategic metals due to their vital industrial applications in storage batteries, nuclear plants, superconducting magnets, steel and chemical production. Its applications in renewable energy in solar panels, hydroelectric and wind energy makes vanadium an indispensable element for green energy or green economy and for our sustainable future (X. Li et al, 2011; Liu et al, 2017; Smith et al, 1985; Valvasori et al, 2020). Vanadium is the twentieth most abundant element in the Earth's crust and can be present in V 3+ , V 4+ and V 5+ valency states in various mineral forms (Fleischer, 1954; Kompanchenko et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…Its applications in renewable energy in solar panels, hydroelectric and wind energy makes vanadium an indispensable element for green energy or green economy and for our sustainable future (X. Li et al, 2011;Liu et al, 2017;Smith et al, 1985;Valvasori et al, 2020). Vanadium is the twentieth most abundant element in the Earth's crust and can be present in V 3+ , V 4+ and V 5+ valency states in various mineral forms (Fleischer, 1954;Kompanchenko et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Origin and evolution of vanadium‐rich oxide and titanite phases in lamprophyre and mafic dykes from the Nuapada diamondiferous Lamproite field, BastarCraton‐EasternGhats Mobile belt contact, India: Metallogenic and geodynamic implications

2023

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Transitional boundaries of the craton and mobile belt mark diverse and long-term tectono-thermal events like hot and cold lithospheric contact, back-arc-type subduction, and also constitute a favourable locale for metallogeny. The exact nature and origin of such metallogenic enrichment in the lithospheric mantle source beneath contact zones are still uncertain. The contact of Bastar Craton and the Eastern Ghat Mobile Belt (EGMB), India, provides an ideal geological setup to study the metallogenic enrichment processes. In this study, we present a detailed petrographic and mineralogical investigation of various iron oxide phases and titanites in spatially and temporally distinct lamprophyre and mafic dykes from the diamondiferous Nuapada Lamproite Field (NLF) at the contact between Bastar Craton and EGMB. Diverse textural assemblages of oxides, namely, trellis, sandwich-type exsolutions and reaction-replacement, are widespread. Ilmenites, magnetites and titanites from the mafic dykes as well as lamprophyre exhibit an anomalous enrichment of vanadium (V 2 O 3 up to 3.7 wt%), whereas ilmenites are also characterized by their elevated manganese content (MnO up to 3.8 wt%). Mineral chemistry-based plots and thermo-oximetric studies suggest the magmatic origin of iron oxides belonging to the Fe-Ti-V-type ore in which partitioning and sequestration of the elements were controlled by differential crystallization, exsolution and fractionation rather than any imprints of contamination. Multiphase sequestration of vanadium as well as manganese in lamprophyre and mafic dykes, separated in space as well in relative depths of origin, signifies the presence of a fertile mantle. The role of subductionderived metasomatized fluids as a causative factor of vanadium metallogeny in this domain is evaluated. Low-Mg and high-Mn ilmenites of this study are consistent with the reported occurrences of diamonds from the NLF and adjoining areas of the Bastar Craton.

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