Inhomogeneous distribution of REE in scheelite and dynamics of Archaean hydrothermal systems (Mt. Charlotte and Drysdale gold deposits, Western Australia)

Brugger, Joël; Lahaye, Yann; Costa, Sylvie; Lambert, David D; Bateman, Roger

doi:10.1007/s004100000135

Cited by 146 publications

(92 citation statements)

References 28 publications

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“…REE patterns of type-3 ferberite incline relatively steeply from the LREE towards the middle rare earth elements (MREE), including strong negative Eu anomalies and weak negative Y anomalies. This pattern is very similar to the REE pattern of primary hydrothermal scheelite, which shows bell-shaped REE patterns enriched in MREE with either positive or negative Eu anomalies and weak Y anomalies [48,49,[57][58][59]. This supports the statement that the replacement of the primary ferberite (type-1) by type-3 ferberite occurred after pseudomorphism, and the elemental composition of the fluid was strongly influenced by the former scheelite.…”

Section: Mineral Chemistrysupporting

confidence: 83%

Mineralogy and Trace Element Chemistry of Ferberite/Reinite from Tungsten Deposits in Central Rwanda

et al. 2013

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Tungsten mineralization in hydrothermal quartz veins from the Nyakabingo, Gifurwe and Bugarama deposits in central Rwanda occurs as the iron-rich endmember of the wolframite solid solution series (ferberite) and in the particular form of reinite, which represents a pseudomorph of ferberite after scheelite. Primary ferberite, reinite and late secondary ferberite are characterized by their trace element chemistry and rare earth element patterns. The replacement of scheelite by ferberite is also documented in the trace element composition. Primary ferberite shows high Mg, Zn, Sc, V, Nb, In and Sn concentrations, but very low Ca, Pb, Sr and Ba contents. Reinite and late secondary ferberite display an uncommon trace element composition containing high concentrations of Ca, Pb, Sr, Ba, As and Ga, but very low levels in Sn, Zr, Hf, In, Ti, Sc, Nb, Ta, Mg and Zn. Late secondary ferberite replacing primary ferberite is characterized by additional enrichments in Bi, Pb, As and Sb. The rare earth element patterns of reinite and secondary ferberite are also similar to hydrothermal scheelite. The formation of the tungsten deposits in central Rwanda is interpreted to be epigenetic in origin, and the hydrothermal mineralizing fluids are related to the intrusion of the G4-granites.

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Section: Mineral Chemistrysupporting

confidence: 83%

Mineralogy and Trace Element Chemistry of Ferberite/Reinite from Tungsten Deposits in Central Rwanda

et al. 2013

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“…In contrast, the characteristics that define the signatures of later generations of apatite associated with hematite-sericite alteration and high-grade ore (MREE-enrichment, positive Eu-and negative Y-anomalies) are less commonly reported. MREE-enriched REY-signatures with weak positive Eu anomalies are particularly scarce in the literature and their description has thus far been limited to orogenic-Au deposits [9,48] and IOCG mineralization within the Olympic Cu-Au belt [10]. Table 1) displaying core-to-rim-and fracture-related zoning consisting of cores rich in REY and REY-depleted rims and fractures.…”

Section: Rey-signatures In Apatite and The Transition From Magmatic Tmentioning

confidence: 99%

Rare Earth Element Behaviour in Apatite from the Olympic Dam Cu–U–Au–Ag Deposit, South Australia

et al. 2017

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Abstract:Apatite is a common magmatic accessory in the intrusive rocks hosting the giant~1590 Ma Olympic Dam (OD) iron-oxide copper gold (IOCG) ore system, South Australia. Moreover, hydrothermal apatite is a locally abundant mineral throughout the altered and mineralized rocks within and enclosing the deposit. Based on compositional data for zoned apatite, we evaluate whether changes in the morphology and the rare earth element and Y (REY) chemistry of apatite can be used to constrain the fluid evolution from early to late hydrothermal stages at OD. The~1.6 Ga Roxby Downs granite (RDG), host to the OD deposit, contains apatite as a magmatic accessory, locally in the high concentrations associated with mafic enclaves. Magmatic apatite commonly contains REY-poor cores and REY-enriched margins. The cores display a light rare earth element (LREE)-enriched chondrite-normalized fractionation pattern with a strong negative Eu anomaly. In contrast, later hydrothermal apatite, confined to samples where magmatic apatite has been obliterated due to advanced hematite-sericite alteration, displays a conspicuous, convex, middle rare earth element (MREE)-enriched pattern with a weak negative Eu anomaly. Such grains contain abundant inclusions of florencite and sericite. Within high-grade bornite ores from the deposit, apatite displays an extremely highly MREE-enriched chondrite-normalized fractionation trend with a positive Eu anomaly. Concentrations of U and Th in apatite mimic the behaviour of ∑REY and are richest in magmatic apatite hosted by RDG and the hydrothermal rims surrounding them. The shift from characteristic LREE-enriched magmatic and early hydrothermal apatite to later hydrothermal apatite displaying marked MREE-enriched trends (with lower U, Th, Pb and ∑REY concentrations) reflects the magmatic to hydrothermal transition. Additionally, the strong positive Eu anomaly in the MREE-enriched trends of apatite in high-grade bornite ores are attributable to alkaline fluid conditions.

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“…This suggests that the unusual MREE-enriched signature of this apatite cannot be explained in terms of solubility and stability discrepancies between the REE. Given the relative lack of co-crystallizing LREE-enriched species within these samples, except for very minor florencite, it is reasonable to suggest that the fluids from which this apatite formed were already slightly MREE-enriched and that the preferential partitioning of REE closest to the Sm-Gd range into apatite [35] led to further MREE-enrichment as was suggested for scheelite under similar conditions [8]. Significantly, within these models, Eu is present as the trivalent species EuO 2 − , a form much more easily incorporated into apatite compared to the EuCl 4 2− species present within the other models.…”

Section: Apatite/fluid Ree Partitioning and The Effects Of Evolving Fmentioning

confidence: 72%

“…Speciation of REE as F-complexes is easily achieved by increasing F concentrations within fluid at low pH and may also need to consider the potential role of REE-CO 3 complexes. These data, from one of the largest REE accumulations on Earth complement published empirical datasets and thermodynamic modeling in a broad range of different ore deposits [1][2][3][4][5][6][7][8][54][55][56].…”

Section: Conclusion and Recommendationsmentioning

confidence: 85%

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Numerical Modeling of REE Fractionation Patterns in Fluorapatite from the Olympic Dam Deposit (South Australia)

et al. 2018

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Trace element signatures in apatite are used to study hydrothermal processes due to the ability of this mineral to chemically record and preserve the impact of individual hydrothermal events. Interpretation of rare earth element (REE)-signatures in hydrothermal apatite can be complex due to not only evolving f O 2 , f S 2 and fluid composition, but also to variety of different REE-complexes (Cl-, F-, P-, SO 4, CO 3 , oxide, OH − etc.) in hydrothermal fluid, and the significant differences in solubility and stability that these complexes exhibit. This contribution applies numerical modeling to evolving REE-signatures in apatite within the Olympic Dam iron-oxide-copper-gold deposit, South Australia with the aim of constraining fluid evolution. The REE-signatures of three unique types of apatite from hydrothermal assemblages that crystallized under partially constrained conditions have been numerically modeled, and the partitioning coefficients between apatite and fluid calculated in each case. Results of these calculations replicate the measured data well and show a transition from early light rare earth element (LREE)-to later middle rare earth element (MREE)-enriched apatite, which can be achieved by an evolution in the proportions of different REE-complexes. Modeling also efficiently explains the switch from REE-signatures with negative to positive Eu-anomalies. REE transport in hydrothermal fluids at Olympic Dam is attributed to REE-chloride complexes, thus explaining both the LREE-enriched character of the deposit and the relatively LREE-depleted nature of later generations of apatite. REE deposition may, however, have been induced by a weakening of REE-Cl activity and subsequent REE complexation with fluoride species. The conspicuous positive Eu-anomalies displayed by later apatite with are attributed to crystallization from high pH fluids characterized by the presence of Eu 3+ species.

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Inhomogeneous distribution of REE in scheelite and dynamics of Archaean hydrothermal systems (Mt. Charlotte and Drysdale gold deposits, Western Australia)

Cited by 146 publications

References 28 publications

Mineralogy and Trace Element Chemistry of Ferberite/Reinite from Tungsten Deposits in Central Rwanda

Mineralogy and Trace Element Chemistry of Ferberite/Reinite from Tungsten Deposits in Central Rwanda

Rare Earth Element Behaviour in Apatite from the Olympic Dam Cu–U–Au–Ag Deposit, South Australia

Numerical Modeling of REE Fractionation Patterns in Fluorapatite from the Olympic Dam Deposit (South Australia)

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