Oxidation state of europium in scheelite: Tracking fluid–rock interaction in gold deposits

Brugger, Joël; Etschmann, Barbara; Pownceby, Mark I.; Liu, Weihua; Grundler, Pascal V.; Brewe, Dale

doi:10.1016/j.chemgeo.2008.08.003

Cited by 147 publications

(57 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The positive Eu anomaly in the high-grade bornite ore hosted apatite may, however, be the result of crystallization from an alkaline, CO 2 -HCO 3 − buffered fluid analogous to that invoked by [50] to explain comparable trends, observed and thermodynamically assessed, in scheelite from orogenic Au deposits (Mt. Charlotte and Drysdale, Western Australia).…”

Section: Rey Signatures In Apatite Associated With High-grade Oresmentioning

confidence: 99%

“…Apatite preferentially incorporates Eu 3+ over Eu 2+ , and although the greatest control on the proportion of the two species is exerted by fO2 in the magmatic environment [8], their speciation in hydrothermal fluids is primarily controlled by H + activity whereby Eu 3+ complexes dominate at high pH conditions (>7 at 300 °C; [50]). Such alkaline conditions are unrealistic for the fluids responsible for the broad hematite-sericite alteration due to the low pH required for sericite stability at this temperature.…”

Section: Rey Signatures In Apatite Associated With High-grade Oresmentioning

confidence: 99%

See 1 more Smart Citation

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

et al. 2017

View full text Add to dashboard Cite

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.

show abstract

Section: Rey Signatures In Apatite Associated With High-grade Oresmentioning

confidence: 99%

Section: Rey Signatures In Apatite Associated With High-grade Oresmentioning

confidence: 99%

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

et al. 2017

View full text Add to dashboard Cite

show abstract

“…This behavior has been used to infer variability or change in redox conditions (e.g., [12]), as well as changes in fluid parameters due to the sensitivity of Eu 3+ /Eu 2+ complexing to pH [2]. No evidence is seen in the deposit for the presence Ce 4+ (e.g., as cerianite), which might also influence partitioning trends.…”

Section: Apatite Mineralogy Geochemistry and Crystal Structurementioning

confidence: 99%

“…Brugger et al [2,8], Smith et al [1] and Migdisov et al [7] have outlined the methodology for calculation of fluid partitioning coefficients in minerals where Ca is a major component. Substitution mechanisms must be defined as a preliminary requisite step.…”

Section: Numerical Modeling Of Apatite/fluid Partitioning Coefficientsmentioning

confidence: 99%

“…Studies have demonstrated the interdependency between hydrothermal conditions and the compositions of specific minerals (e.g., [1][2][3]). Many such studies have focused on the rare earth elements (REE), which display a coherent behavior to one another due to similar electronic configurations, common trivalent oxidation state, and systematic decrease in atomic radius with increased atomic number.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

et al. 2018

View full text Add to dashboard Cite

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.

show abstract

The REE s in Hydrothermal Systems

Migdisov¹,

Williams‐Jones²,

Brugger³

2019

Encyclopedia of Water

View full text Add to dashboard Cite

Extensive use of the rare earth elements (REEs, mostly represented by the lanthanide group from La to Lu) in renewable energy applications and defense‐related technologies triggered high and growing interest to the processes responsible for migration, separation, and concentration of these elements in natural processes. Understanding these processes and the behavior of REEs in them is essential for exploration of new resources of these elements and efficient use of REEs in industrial applications. There is now an almost universal agreement that hot aqueous fluids play a significant and, in some cases, a dominant role in concentration and separation of REEs in nature. This article reviews high‐temperature experimental data collected over the past 15 years on the stability of the REE aqueous species and minerals and discusses the mechanisms responsible for hydrothermal transport and deposition of the REEs.

show abstract

Oxidation state of europium in scheelite: Tracking fluid–rock interaction in gold deposits

Cited by 147 publications

References 27 publications

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

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)

The REE s in Hydrothermal Systems

Contact Info

Product

Resources

About