J. Trofanenko

Bio: J. Trofanenko is an academic researcher from McGill University. The author has contributed to research in topics: Carbonatite & Fenite. The author has an hindex of 1, co-authored 1 publications receiving 46 citations.

The Nature and Origin of the REE Mineralization in the Wicheeda Carbonatite, British Columbia, Canada

Abstract: The Wicheeda carbonatite is a deformed plug or sill that hosts relatively high grade light rare earth elements (LREE) mineralization in the British Columbia alkaline province. It was emplaced within metasedimentary rocks belonging to the Kechika Group, which have been altered to potassic fenite near the intrusion and sodic fenite at greater distances from it. The intrusion comprises a ferroan dolomite carbonatite core, which passes gradationally outward into calcite carbonatite. The potentially economic REE mineralization is hosted by the dolomite carbonatite. Three types of dolomite have been recognized. Dolomite 1 constitutes the bulk of the dolomite carbonatite, dolomite 2 replaced dolomite 1 near veins and vugs, and dolomite 3 occurs in veins and vugs together with the REE mineralization. Carbon and oxygen isotope ratios indicate that the calcite carbonatite crystallized from a magma of mantle origin, that dolomite 1 is of primary igneous origin, that dolomite 2 has a largely igneous signature with a small hydrothermal component, and that dolomite 3 is of hydrothermal origin. The REE minerals comprise REE fluorocarbonates, ancylite-(Ce), and monazite-(Ce). In addition to dolomite 3, they occur with barite, molybdenite, pyrite, and thorite. Minor concentrations of niobium are present as magmatic pyrochlore in the calcite carbonatite. A model is proposed in which crystallization of calcite carbonatite preceded that of dolomite carbonatite. During crystallization of the latter, an aqueous-carbonic fluid was exsolved, which mobilized the REE as chloride complexes into vugs and fractures in the dolomite carbonatite, where they precipitated mainly in response to the increase in pH that accompanied fluid-rock interaction and, in the case of the REE fluorocarbonates, decreasing temperature. These fluids altered the host metasedimentary rock to potassic fenite adjacent to the carbonatite and, distal to it, they mixed with formational waters to produce sodic fenite.

Carbonatites: related ore deposits, resources, footprint, and exploration methods

Abstract: Most carbonatites were emplaced in continental extensional settings and range in age from Archean to recent. They commonly coexist with alkaline silicate igneous rocks, forming alkaline-carbonatite...

Rare earth element mobility in and around carbonatites controlled by sodium, potassium, and silica

Abstract: Carbonatites and associated rocks are the main source of rare earth elements (REEs), metals essential to modern technologies. REE mineralization occurs in hydrothermal assemblages within or near carbonatites, suggesting aqueous transport of REE. We conducted experiments from 1200°C and 1.5 GPa to 200°C and 0.2 GPa using light (La) and heavy (Dy) REE, crystallizing fluorapatite intergrown with calcite through dolomite to ankerite. All experiments contained solutions with anions previously thought to mobilize REE (chloride, fluoride, and carbonate), but REEs were extensively soluble only when alkalis were present. Dysprosium was more soluble than lanthanum when alkali complexed. Addition of silica either traps REE in early crystallizing apatite or negates solubility increases by immobilizing alkalis in silicates. Anionic species such as halogens and carbonates are not sufficient for REE mobility. Additional complexing with alkalis is required for substantial REE transport in and around carbonatites as a precursor for economic grade-mineralization.

Multi-stage formation of REE minerals in the Palabora Carbonatite Complex, South Africa

Abstract: The 2060 Ma old Palabora Carbonatite Complex (PCC), South Africa, comprises diverse REE mineral assemblages formed during different stages and reflects an outstanding instance to understand the evolution of a carbonatite-related REE mineralization from orthomagmatic to late-magmatic stages and their secondary post-magmatic overprint The 10 rare earth element minerals monazite, REE-F-carbonates (bastnasite, parisite, synchysite), ancylite, britholite, cordylite, fergusonite, REE-Ti-betafite, and anzaite are texturally described and related to the evolutionary stages of the PCC The identification of the latter five REE minerals during this study represents their first described occurrences in the PCC as well as in a carbonatite complex in South Africa The variable REE mineral assemblages reflect a multi-stage origin: (1) fergusonite and REE-Ti-betafite occur as inclusions in primary magnetite Bastnasite is enclosed in primary calcite and dolomite These three REE minerals are interpreted as orthomagmatic crystallization products (2) The most common REE minerals are monazite replacing primary apatite, and britholite texturally related to the serpentinization of forsterite or the replacement of forsterite by chondrodite Textural relationships suggest that these two REE-minerals precipitated from internally derived late-magmatic to hydrothermal fluids Their presence seems to be locally controlled by favorable chemical conditions (eg, presence of precursor minerals that contributed the necessary anions and/or cations for their formation) (3) Late-stage (post-magmatic) REE minerals include ancylite and cordylite replacing primary magmatic REE-Sr-carbonates, anzaite associated with the dissolution of ilmenite, and secondary REE-F-carbonates The formation of these post-magmatic REE minerals depends on the local availability of a fluid, whose composition is at least partly controlled by the dissolution of primary minerals (eg, REE-fluorocarbonates) This multi-stage REE mineralization reflects the interplay of magmatic differentiation, destabilization of early magmatic minerals during subsequent evolutionary stages of the carbonatitic system, and late-stage fluid-induced remobilization and re-/precipitation of precursor REE minerals Based on our findings, the Palabora Carbonatite Complex experienced at least two successive stages of intense fluid–rock interaction