Carbonatite-hosted niobium deposit at Aley, northern British Columbia (Canada): Mineralogy, geochemistry and petrogenesis

Chakhmouradian, Anton R.; Reguir, Ekaterina P.; Kressall, Ryan; Crozier, Jeremy; Pisiak, Laura K.; Sidhu, Ravinder; Yang, Panseok

doi:10.1016/j.oregeorev.2014.04.020

Cited by 88 publications

(67 citation statements)

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“…However, we note that fluorcalciopyrochlore from the well-known Nb-REE Bayan Obo deposit was originally described as a product of REE-, F-rich postmagmatic hydrothermal solutions impact on Ca-Mg-carbonatites [61]. Moreover, in exocontact rocks (fenites) of late carbonatites a priori fluid pyrochlore mineralization is also usually represented by fluorcalciopyrochlore [56,62]. We suggest both U-Th, and Ca-F-varieties of pyrochlore formed when apatite occurred in titaniferous carbonatites, which is indicated by the similar chemical features of both minerals (e.g., increased contents of Th, Y, Sr, etc.…”

Section: Discussionmentioning

confidence: 87%

Ti-Nb Mineralization of Late Carbonatites and Role of Fluids in Its Formation: Petyayan-Vara Rare-Earth Carbonatites (Vuoriyarvi Massif, Russia)

et al. 2018

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This article is devoted to the geology of titanium-rich varieties of the Petyayan-Vara rare-earth dolomitic carbonatites in Vuoriyarvi, Northwest Russia. Analogues of these varieties are present in many carbonatite complexes. The aim of this study was to investigate the behavior of high field strength elements during the late stages of carbonatite formation. We conducted a multilateral study of titanium-and niobium-bearing minerals, including a petrographic study, Raman spectroscopy, microprobe determination of chemical composition, and electron backscatter diffraction. Three TiO 2 -polymorphs (anatase, brookite and rutile) and three pyrochlore group members (hydroxycalcio-, fluorcalcio-, and kenoplumbopyrochlore) were found to coexist in the studied rocks. The formation of these minerals occurred in several stages. First, Nb-poor Ti-oxides were formed in the fluid-permeable zones. The overprinting of this assemblage by residual fluids led to the generation of Nb-rich brookite (the main niobium concentrator in the Petyayan-Vara) and minerals of the pyrochlore group. This process also caused niobium enrichment with of early generations of Ti oxides. Our results indicate abrupt changes in the physicochemical parameters at the late hydro (carbo) thermal stage of the carbonatite formation and high migration capacity of Ti and Nb under these conditions. The metasomatism was accompanied by the separation of these elements.

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Section: Discussionmentioning

confidence: 87%

Ti-Nb Mineralization of Late Carbonatites and Role of Fluids in Its Formation: Petyayan-Vara Rare-Earth Carbonatites (Vuoriyarvi Massif, Russia)

et al. 2018

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“…Khamrabayev et al (1992) observe that micas found in association with carbonatites are often devoid of any accessory inclusions such as apatite and zircon that are typical of igneous mica. Textural evidence and alteration patterns therefore suggest that at least some glimmerites associated with carbonatites are the result of metasomatic alteration of Mg-rich country rocks and are not igneous in origin (Khamrabayev et al, 1992;Rosatelli et al, 2003;Jones et al, 2013;Chakhmouradian et al, 2015).…”

Section: Glimmeritesmentioning

confidence: 99%

Fenites associated with carbonatite complexes: A review

Elliott

Wall

Chakhmouradian

et al. 2018

Ore Geology Reviews

151

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A B S T R A C TCarbonatites and alkaline-silicate rocks are the most important sources of rare earth elements (REE) and niobium (Nb), both of which are metals imperative to technological advancement and associated with high risks of supply interruption. Cooling and crystallizing carbonatitic and alkaline melts expel multiple pulses of alkali-rich aqueous fluids which metasomatize the surrounding country rocks, forming fenites during a process called fenitization. These alkalis and volatiles are original constituents of the magma that are not recorded in the carbonatite rock, and therefore fenites should not be dismissed during the description of a carbonatite system. This paper reviews the existing literature, focusing on 17 worldwide carbonatite complexes whose attributes are used to discuss the main features and processes of fenitization. Although many attempts have been made in the literature to categorize and name fenites, it is recommended that the IUGS metamorphic nomenclature be used to describe predominant mineralogy and textures. Complexing anions greatly enhance the solubility of REE and Nb in these fenitizing fluids, mobilizing them into the surrounding country rock, and precipitating REE-and Nb-enriched micro-mineral assemblages. As such, fenites have significant potential to be used as an exploration tool to find mineralized intrusions in a similar way alteration patterns are used in other ore systems, such as porphyry copper deposits. Strong trends have been identified between the presence of more complex veining textures, mineralogy and brecciation in fenites with intermediate stage Nb-enriched and later stage REE-enriched magmas. However, compiling this evidence has also highlighted large gaps in the literature relating to fenitization. These need to be addressed before fenite can be used as a comprehensive and effective exploration tool.

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“…In this respect, carbonatites are commonly treated similarly to other igneous rocks, which is a mistake. For example, some strongly metamorphosed carbonatites showing preferred orientation and modal layering have been misinterpreted as products of magma flow and differentiation (see discussion in Chakhmouradian et al 2015a). In comparison to the majority of igneous rocks composed of silicate minerals, carbonatites are readily susceptible to textural and compositional re-equilibration (e.g., recrysallization and isotopic resetting, respectively), grain abrasion, fragmentation and comminution, ductile deformation, dissolution and other forms of chemical interaction with fluids even at relatively low T and P. For example, fine-grained felsic rocks exhibit textural evidence of semi-brittle flow at T generally in excess of 600°C and P≥10 kbar, whereas the brittle-ductile transition in calcite marble of similar texture will occur at P<1 kbar even at ambient T (Fredrich et al 1989;Hirth and Tullis 1994;Snoke et al 2014).…”

Section: Interpretation Of Carbonatite Textures: Challenges and Limitmentioning

confidence: 99%

“…These textures are interpreted as eutectic based on a careful analysis of the orientation and compositional variation of their constituent minerals. Plutonic carbonatites commonly grade into meso-to melanocratic cumulate rocks spanning a wide range of modal compositions dominated by apatite, silicates (major olivine, phlogopite, diopside, nepheline, calcic amphibole or andradite with accessory zircon and titanite), or oxides (major magnetite, pyrochlore, perovskite or ferrocolumbite with accessory ilmenite, rutile, baddeleyite, zirconolite and calzirtite); pyrrhot i t e a n d p y r i te a r e t y p i c a l s u l f i d e c o n s t i t u e n t s (Chakhmouradian and Zaitsev 2004;Chakhmouradian et al 2015a;Mitchell 2015). In these rocks, primary carbonate minerals occur as interstitial grains (Fig.…”

Section: Igneous Textures: Key Examplesmentioning

confidence: 99%

“…Surprisingly, however, there appears to have been no attempt in the literature to provide a comprehensive analysis of textures exhibited by these minerals. Some studies addressed textural variations within a series of genetically related rocks (e.g., Platt and Woolley 1990;Zaitsev 1996;Zaitsev et al 2004Zaitsev et al , 2008Chakhmouradian et al 2015a), i.e. on the scale of a single locality, but none approached this task in a systematic fashion and on the basis of multiple observations from many carbonatite occurrences.…”

Section: Introductionmentioning

confidence: 99%

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Calcite and dolomite in intrusive carbonatites. I. Textural variations

2015

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Carbonatites are nominally igneous rocks, whose evolution commonly involves also a variety of postmagmatic processes, including exsolution, subsolidus re-equilibration of igneous mineral assemblages with fluids of different provenance, hydrothermal crystallization, recrystallization and tectonic mobilization. Petrogenetic interpretation of carbonatites and assessment of their mineral potential are impossible without understanding the textural and compositional effects of both magmatic and postmagmatic processes on the principal constituents of these rocks. In the present work, we describe the major (micro)textural characteristics of carbonatitic calcite and dolomite in the context of magma evolution, fluid-rock interaction, or deformation, and provide information on the compositional variation of these minerals and its relation to specific evolutionary processes.

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Carbonatite-hosted niobium deposit at Aley, northern British Columbia (Canada): Mineralogy, geochemistry and petrogenesis

Cited by 88 publications

References 56 publications

Ti-Nb Mineralization of Late Carbonatites and Role of Fluids in Its Formation: Petyayan-Vara Rare-Earth Carbonatites (Vuoriyarvi Massif, Russia)

Ti-Nb Mineralization of Late Carbonatites and Role of Fluids in Its Formation: Petyayan-Vara Rare-Earth Carbonatites (Vuoriyarvi Massif, Russia)

Fenites associated with carbonatite complexes: A review

Calcite and dolomite in intrusive carbonatites. I. Textural variations

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