Rare earth element (REE) geochemistry of different colored fluorites from the Baoshan Cu–Pb–Zn deposit, Southern Hunan, South China

Huang, Jing; Peng, Jiantang

doi:10.1007/s11631-022-00538-x

Cited by 4 publications

(4 citation statements)

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“…Obvious differences in diffusion constants for Sr in apatite have been observed under anhydrous and hydrous conditions (Farver and Giletti, 1989;Cherniak and Ryerson, 1993), and the presence of water has also been shown to enhance O transport significantly in quartz , zircon (Watson and Cherniak, 1997), anorthite , and upon CaAl-NaSi interdiffusion in plagioclase (Yund and Snow, 1989). Moreover, alteration haloes can facilitate trace element mobility by fluids infiltrating along the rim of mineral grains or within fractures, which would likely cause surface layer(s) of scheelite crystals to differ from their internal portions in terms of REE patterns and Eu anomaly characteristics (Zhang et al, 2012a). Thus, in order to eliminate the effects of water or fluid-based processes, samples for isotopic dating and tracing, no matter for which isotope dilution technique or the in-situ approach used, must be "pristine" and free of alteration.…”

Section: Discussionmentioning

confidence: 99%

“…REE zoning have been reported in scheelite from a range of deposits, with zone widths varying from below 1 μm to 200 μm (e.g., Brugger et al, 2000a;Peng et al, 2010;Wang et al, 2021). In many investigations on REE zoning or their inhomogeneous distribution, the beam spots for micro-analyses are generally on the scale of 30-80 μm, such as would be typical of LA-ICP-MS methods (e.g., Brugger et al, 2000a;Schwinn and Markl, 2005;Schönenberger et al, 2008;Zhang et al, 2012a;Ke et al, 2020;Poitrenaud et al, 2020). It is clear that, at this scale, Sm-Nd information in scheelite zoning is modified solely by chemical diffusion.…”

Section: Ree Zones In Scheelitementioning

confidence: 99%

“…2008; Peng et al, 2003;Zhang et al, 2012a;Sciuba et al, 2020;Wang et al, 2021). Sm-Nd isochron dating method represents a very useful geochronologic tool for dating hydrothermal activities, whereby Nd is a most effective tracer to monitor the evolution of the mineralizing fluids (Fryer and Taylor, 1984;Liu et al, 2007;Dostal et al, 2009;Fisher et al, 2020).…”

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confidence: 99%

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Diffusion of Sm‐Nd in Scheelite and its Significance to Isotopic Dating and Tracing

ZHANG

Coulson

PENG

et al. 2023

Acta Geologica Sinica (Eng)

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As the principal ore mineral in various tungsten (‐gold) deposits, scheelite (CaWO4) plays an important role in directly dating the timing of ore formation, and in tracing associated material sources through the study of its Sm‐Nd geochronology and Nd isotopic characteristics. Since the retention of Sm‐Nd systematics within scheelite is presently unconstrained, equivocal interpretations for isotopic data resulting from this method have occurred quite often in previous studies that apply these isotopic data. In order to better elucidate the closure of Sm‐Nd in scheelite, the kinetics of Sm and Nd within this mineral lattice were investigated through calculation of diffusion constants presented herein. The following Arrhenius relations were obtained: showing diffusion rate of Nd is near identical to Sm in scheelite when at the same temperature. However, compared to other rare earth elements (REEs), which have markedly different atomic radii to either Nd or Sm, these are shown to exhibit a great variation in diffusivities. The observed trends in our data are in excellent agreement with the diffusion characteristics of REEs in other tetragonal ABO4 minerals, indicating that ionic radius is a key constraint to the diffusivity of REEs in the various crystal lattices. With this in mind, the same substitution mechanism and a very slight discrepancy in radii will allow us to infer that significant Sm/Nd diffusional fractionation in scheelite is unlikely to occur during most geological processes. Based upon the diffusion data determined herein, Sm and Nd closure temperatures and retention times in scheelite are discussed in terms of diffusion dynamics. Those results suggest that closure temperatures for Sm‐Nd within this mineral are relatively high in contrast to the temperature ranges of ore‐formation responsible for scheelite‐related deposits, and any later thermal environments. It is likely, therefore, that relevant isotopic information could be easily retained under most geological conditions, since initial crystallization of the scheelite. In addition, comparison of this mineral‐element pair over a range of temperatures with some other common minerals used as geochronometers (e.g., zircon and apatite) indicates that Sm‐Nd system has a slower diffusive rate in scheelite than for Sr in apatite or Ar in quartz, and only a little faster than for Pb in zircon. It should be noted, within most hydrothermal deposits where zircon has crystallized, its size is typically no more than 100 μm, whereas scheelite commonly occurs as macroscopic grains. For this reason, the larger dimensions of scheelite would provide a robust Sm‐Nd system more able to resist perturbations, relating to any later thermal process. As such Sm‐Nd investigations of scheelite are akin to U‐Pb within zircon samples used in isotopic dating. These observations indicate that Sm‐Nd age and isotopic information can provide reliable data in all but the most extreme case, especially when data are extracted from macroscopic grains of scheelite that are c...

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Section: Discussionmentioning

confidence: 99%

Section: Ree Zones In Scheelitementioning

confidence: 99%

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Diffusion of Sm‐Nd in Scheelite and its Significance to Isotopic Dating and Tracing

ZHANG

Coulson

PENG

et al. 2023

Acta Geologica Sinica (Eng)

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“…In recent years, the three-state continuous extraction method of the BCR has been widely used in the research of heavy metal elements in soil, sludge, and other media. Chen D et al used the improved continuous extraction method of BCR to effectively analyze the effects of three aging methods, four types of biochar, and aging time on the chemical forms of Pb in soil [12]. Hu QQ and other researchers used Scanning Electron Microscopy-Energy Dispersive Spectrometer (SEM-EDS) and BCR to continuously extract heavy metals.…”

Section: Introductionmentioning

confidence: 99%

Study of the Remediation Effect and Mechanism of Biochar-Loaded nZVI on Heavy Metal Contaminated Soil

Duan,

Ren,

Tao

et al. 2023

Sustainability

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Soil heavy metal pollution has become an important environmental problem in the world. Therefore, it is particularly important to find effective remediation methods for heavy metal contaminated soil. Biochar (BC) is a kind of soil heavy metal passivator with a wide range of applications. It also has a good effect on the control of soil heavy metal pollution. However, BC does not have sufficient fixation capacity for para-anionic contaminants. Nano-zero-valent iron (nZVI) has a strong reducing ability, which can make up for this defect of BC. Therefore, to improve the passivation effect of heavy metals, nanomaterial modification is proposed to optimize biochar performance. Nanoparticles are used as carriers to impregnate biochar (BC). Biochar-supported nano-ferric zero-valent materials are prepared to repair soil contaminated by heavy metals. Results show that the physicochemical properties of modified biochar are significantly optimized. At 5%, the modified biochar (1:3) treatment group had the best remediation effect on Cd-contaminated soil, which significantly promoted soil catalase activity. The modified biochar (3:1) treatment group had the best remediation effect on As-contaminated soil, and significantly increased soil pH, Cation Exchange Capacity (CEC), and available Fe content. Modified biochar (1:3) with 3% added content was used to repair actual composite heavy metal contaminated soil, and the relative percentage content of Cu, Zn, As, Cd, and Pb residue state increased by 10.28%, 7.81%, 7.44%, 9.26%, and 12.75%, respectively. The effects of nZVI@BC on the remediation effect and soil enzymes of Cd- and As-contaminated soil under different factors such as mass ratio of carbon and iron and dosage were studied. The remediation mechanism of Cd- and As-contaminated soil was clarified, and a good solidification and stabilization effect was obtained. This provides a theoretical basis for nZVI@BC remediation of soil contaminated by Cd and As. It has good application value in the treatment and remediation of complex heavy metal contaminated soil.

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Relationship between Pb-Zn and Au mineralization in the Laoyachao deposit, South China: Constraints from geology and S-Pb-He-Ar isotopes

Huang,

Peng,

Xie

et al. 2024

Journal of Asian Earth Sciences

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Rare earth element (REE) geochemistry of different colored fluorites from the Baoshan Cu–Pb–Zn deposit, Southern Hunan, South China

Cited by 4 publications

References 43 publications

Diffusion of Sm‐Nd in Scheelite and its Significance to Isotopic Dating and Tracing

Diffusion of Sm‐Nd in Scheelite and its Significance to Isotopic Dating and Tracing

Study of the Remediation Effect and Mechanism of Biochar-Loaded nZVI on Heavy Metal Contaminated Soil

Relationship between Pb-Zn and Au mineralization in the Laoyachao deposit, South China: Constraints from geology and S-Pb-He-Ar isotopes

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