The Origin of Niobium and Tantalum Mineralization in the Nechalacho REE Deposit, NWT, Canada

Timofeev, Alexander; Williams‐Jones, Anthony E.

doi:10.2113/econgeo.110.7.1719

Cited by 41 publications

(13 citation statements)

References 17 publications

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“…It is based on the observation that the primary mineral is altered first to a phase with the composition of the pyrochlore group minerals Table S2. Please refer also to Hogarth and Horne (1989), Lumpkin and Ewing (1996), Uher et al (1998), Chakhmouradian and Mitchell (2002), Zurevinski and Mitchell (2004), Caprilli et al (2006), Monchoux et al (2006), Mokhov et al (2008), Abd El-Naby (2009), Timofeev and Williams-Jones (2015) or directly to Pb-, Bi-, U-rich pyrochlores, and then possibly to liandratite (i.e. Fig.…”

Section: Discussionmentioning

confidence: 99%

Liandratite from Karkonosze pegmatites, Sudetes, Southwestern Poland

Matyszczak

2017

Miner Petrol

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Section: Discussionmentioning

confidence: 99%

Liandratite from Karkonosze pegmatites, Sudetes, Southwestern Poland

Matyszczak

2017

Miner Petrol

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“…Fluorcalciopyrochlore (Ca,Na) 2 Nb 2 O 6 F is the most widespread phase in the group [3,10,12]. Findings of pyrochlore with prominent Na enrichment over Ca and other cations at the A-site are very few and are limited to several rare-metal deposits hosted by the Nechalacho syenite and nepheline syenite (Canada) [13,14], the Mariupol nepheline syenite (Ukraine) [15], the Strange Lake granite (Canada) [16], and the Halzdan-Buregteg alkaline granite (West Mongolia) [17]. Fluornatropyrochlore (Na,Pb,Ca,REE,U) 2 Nb 2 O 6 F was reported as a mineral species from the Boziguoer granites (China) only in 2013 [18].…”

Section: Introductionmentioning

confidence: 99%

Pyrochlore-Group Minerals in the Granite-Hosted Katugin Rare-Metal Deposit, Transbaikalia, Russia

et al. 2019

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Pyrochlore group minerals are the main raw phases in granitic rocks of the Katugin complex-ore deposit that stores Nb, Ta, Y, REE, U, Th, Zr, and cryolite. There are three main types: Primary magmatic, early postmagmatic (secondary-I), and late hydrothermal (secondary-II) pyrochlores. The primary magmatic phase is fluornatropyrochlore, which has high concentrations of Na2O (to 10.5 wt.%), F (to 5.4 wt.%), and REE2O3 (to 17.3 wt.%) but also low CaO (0.6–4.3 wt.%), UO2 (to 2.6 wt.%), ThO2 (to 1.8 wt.%), and PbO (to 1.4 wt.%). Pyrochlore of this type is very rare in nature and is limited to a few occurrences: Rare-metal deposits of Nechalacho in syenite and nepheline syenite (Canada) and Mariupol in nepheline syenite (Ukraine). It may have crystallized synchronously with or slightly later than melanocratic minerals (aegirine, biotite, and arfvedsonite) at the late magmatic stage when Fe from the melt became bound, which hindered the crystallization of columbite. Secondary-I pyrochlore follows cracks or replaces primary pyrochlore in grain rims and is compositionally similar to the early phase, except for lower Na2O concentrations (2.8 wt.%), relatively low F (4 wt.%), and less complete A- and Y-sites occupancy. Secondary-II pyrochlore is a product of late hydrothermal alteration, which postdated the formation of the Katugin deposit. It differs in large ranges of elements and contains minor K, Ba, Pb, Fe, and significant Si concentrations but also low Na and F. Its composition mostly falls within the field of hydro- and keno-pyrochlore.

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“…In the absence of crustal contamination (Wang, Xu, et al, ), these ore‐forming elements are incorporated into the rock‐forming or accessory minerals during late stages of crystallization differentiation as magmatic evolution progresses. In alkaline/peralkaline igneous rocks, such as Thor Lake, Baerzhe, and Boziguoer, magmatism mainly enriches primary magmatic minerals, such as eudyalite, pyrochlore, monazite, zircon, columbite, and fergusenite, in Nb and REE (Huang et al, ; Sheard et al, ; Timofeev & Williams‐Jones, ; Yang et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…This is similar to other Nb–REE deposits in alkaline/peralkaline igneous rocks, such as the deposit Strange Lake in peralkaline granites (Gysi, Williams‐Jones, & Collins, ; Salvi & Williams‐Jones, ; Sheard et al, ) and the Brockman and Toongi deposits in peralkaline volcanic rocks (Ramsden, French, & Chalmers, ; Spandler & Morris, ). A combination of magmatic and post‐magmatic hydrothermal fluids may have caused the Nb–REE mineralization associated with K–Na alteration in these deposits (Sheard et al, ; Timofeev & Williams‐Jones, ). Second, the halogen fugacity of the hydrothermal fluid in the Zhujiayuan deposit was relatively high, similar to magmatic‐hydrothermal porphyry deposits.…”

Section: Discussionmentioning

confidence: 99%

Mineralogical constraints on Nb–REE mineralization of the Zhujiayuan Nb (−REE) deposit in the North Daba Mountain, South Qinling, China

et al. 2019

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The trachyte-hosted Zhujiayuan deposit is located in the North Daba Mountain of South Qinling, China. In this deposit, the presence of different stages and genetic types of biotite, apatite, and rutile make it an excellent locality to constrain the mineralization process of Nb-REE in the alkaline igneous rock. In this study, supported by electron probe microanalyzer (EPMA), chemical analyses of biotite, apatite, rutile, columbite-group minerals, fersmite, monazite, and aeschynite-group minerals were presented. Three types of biotite were identified, including magmatic (Bt-1), reequilibrated (Bt-2), and hydrothermal biotite (Bt-3). Apatite can be divided into two types: magmatic (Ap-1) and hydrothermal apatite (Ap-2). Rutile can also be divided into two types: magmatic (Rt-1) and hydrothermal rutile (Rt-2). Rt-1 and Ap-1 contain average 1.44 wt% Nb 2 O 5 and 4.14 wt% LRE 2 O 3 , respectively, indicating that certain concentrations of Nb and REE were incorporated into the rutile and apatite, respectively, during the magmatic crystallization process. The distributions of the columbite-group, fersmite, monazite, and aeschynite-group minerals, as well as the compositional characteristics of monazite, indicate the important role of hydrothermal metasomatism during Nb-REE mineralization. The compositional characteristics of Bt-2 indicate relatively high F and Cl fugacities in the hydrothermal fluid. Bt-2 and Bt-3 both have higher Nb 2 O 5 content than Bt-1, indicating a higher Nb content in the fluid. The source of fluidic Nb likely derived from the metasomatism of magmatic rutile. The REE content decreased from Ap-1 to Ap-2, possibly due to a dissolutionreprecipitation process. The compositional changes from Bt-1 to Bt-3 and Ap-1 to Ap-2 also revealed a decrease in temperature, increase in oxygen fugacity, and increase in Ca content from the magmatic to the hydrothermal system. We speculate that rutile and apatite may have originally formed from an Nb-REE-rich alkalinesilicate melt derived from the metasomatized mantle, which led to the initial Nb-REE enrichment. Subsequent hydrothermal alteration by hydrothermal fluids rich in F and Cl, accompanied by changes in the above physical and chemical conditions and fluid composition, caused a relatively limited and localized remobilization of Nb-REE into the fractures and vesicles in the trachyte.

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The Origin of Niobium and Tantalum Mineralization in the Nechalacho REE Deposit, NWT, Canada

Cited by 41 publications

References 17 publications

Liandratite from Karkonosze pegmatites, Sudetes, Southwestern Poland

Liandratite from Karkonosze pegmatites, Sudetes, Southwestern Poland

Pyrochlore-Group Minerals in the Granite-Hosted Katugin Rare-Metal Deposit, Transbaikalia, Russia

Mineralogical constraints on Nb–REE mineralization of the Zhujiayuan Nb (−REE) deposit in the North Daba Mountain, South Qinling, China

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