Geochemical characteristics and significance of apatite from the Koktokay pegmatitic rare-metal deposit, Altay, Xinjiang

Bai, Ying-Xiong; Shen, Ping; Cao, Chong; Pan, Hongdi; Li, Changhao; Luo, Yi; Huang, Feng; Suo, Qing-Yu

doi:10.18654/1000-0569/2021.09.15

Cited by 6 publications

(5 citation statements)

References 64 publications

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“…For another case, a δCe verse δEu plot is demonstrated to reflect the degree of magma redox and oxygen escape (Figure 10). It has been reported that the feature of Eu anomaly is barely affected by the crystallization of feldspar during a magmatic-hydrothermal process [12]. Subsequently, the heavy Eu anomalies of apatite from Altay No.3 pegmatites may indicate a reduced pegmatitic magma, except for one apatite from Zone 1 and apatite from Zone 6, which display moderate oxidized conditions [52].…”

Section: Oxidation State Of Apatitementioning

confidence: 95%

“…is barely affected by the crystallization of feldspar during a magmatic-hydrother cess [12]. Subsequently, the heavy Eu anomalies of apatite from Altay No.3 pe may indicate a reduced pegmatitic magma, except for one apatite from Zone 1 and from Zone 6, which display moderate oxidized conditions [52].…”

Section: Source and Process Of Mineralization Based On Apatite Charac...mentioning

confidence: 98%

“…Moreover, the experiment data instead showed a dominant role of the melt structure in controlling Mn partitioning [14]. The valence changes in Eu and Ce under different redox conditions infer an alternative method to probe the magmatic f O 2 employed within apatite chemistry [2,[11][12][13]. However, the usage of Eu anomalies as an oxybarometer is largely dependent on the melt bulk composition, as the prior removal of plagioclase from the system can also contribute to Eu anomalies in apatite [15].…”

Section: Introductionmentioning

confidence: 97%

“…Apatite shows a slight selectivity for middle rare-earth elements (MREEs), with a convex upward mineral/melt partition coefficient pattern. Bai et al (2021) [12] suggested that the exsolution of Cl fluid from the melts may result in light rare-earth element (LREE) depletion in pegmatite apatite from the Altay Koktokay pegmatitic rare-metal deposit. Mn, Eu, and Ce are redox-sensitive elements in apatite that could also offer insight into the magmatic oxygen fugacity, i.e., f O 2 .…”

Section: Introductionmentioning

confidence: 99%

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U–Pb Dating, Gemology, and Chemical Composition of Apatite from Dara-e-Pech, Afghanistan

Lai,

Xu,

Zhao

2023

Crystals

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Minerals of the apatite group commonly occur in granite pegmatites, and their ability to incorporate a wide range of trace elements makes them a good indicator of magma composition and magmatic–hydrothermal processes. Gem-quality purple apatite crystals from the Dara-e-Pech pegmatite field in Afghanistan have rarely been reported. Here, we investigated apatite crystals originated from this locality, using gemological testing, chemical analysis, and in situ U–Pb dating, with the purpose of identifying their origin, the constraints on the magma source in which the apatite crystals were formed, and the timing of the magmatic–hydrothermal activity. Our findings demonstrate that the purple apatite crystals were impure fluorapatite, characterized by heavy rare-earth element (HREE) enrichment, intermediate Eu anomalies, and non-CHARAC Y/Ho ratios. The results showed that these apatite crystals yielded a lower intercept age of 135.8 ± 6.9 Ma. We proposed that the pegmatitic apatite samples formed in a transitional magmatic–hydrothermal pegmatitic system with moderate fO2 in the Early Cretaceous (~135 Ma). Our study helps to constrain the magmatic–hydrothermal activities of the little-known Dara-e-Pech pegmatite field.

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Section: Oxidation State Of Apatitementioning

confidence: 95%

Section: Source and Process Of Mineralization Based On Apatite Charac...mentioning

confidence: 98%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

U–Pb Dating, Gemology, and Chemical Composition of Apatite from Dara-e-Pech, Afghanistan

Lai,

Xu,

Zhao

2023

Crystals

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“…As, U, Fe, Mn, and Eu are all redox elements with electrovalence changes, especially Eu (F. S. Zheng & Song, 2023). Most studies show that Eu 3+ readily substitutes for Ca 2+ in apatite crystal structural, which is different from that in plagioclase characterized by Eu 2+ substitution of Ca 2+ (Bai et al, 2021;Belousova et al, 2002;Pan & Fleet, 2002;Sha & Chappell, 1999;Shannon, 1976; J. M. Wang et al, 1986;Watson & Green, 1981;Zeng et al, 2012). The Eu anomaly may result from various factors, including crystal chemical effects (Brugger et al, 2008), original fluid Eu anomaly characteristics (Ghaderi et al, 1999), and especially hydrothermal redox conditions (F. S. Zheng & Song, 2023).…”

Section: Primary Controlling Factors For Machine Learning Classificationmentioning

confidence: 99%

Primary Controlling Factors of Apatite Trace Element Composition and Implications for Exploration in Orogenic Gold Deposits

Cao,

Chen,

Zhang

et al. 2024

Geochem Geophys Geosyst

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Significant and readily accessible orogenic gold deposits have been previously recognized, exploited, and progressively depleted. Innovative approaches are required to discover new and deeply buried deposits. Recently, trace element variations in apatite have been used to distinguish fertile and barren environments as reliable mineral exploration tools. In this study, machine learning models using Random Forest and Deep Neutral Network are utilized to assess the fertility of quartz veins and altered zones in the orogenic gold systems. The two models have been trained using trace element data of apatite, and the performance of both models yield good classification accuracy (∼90% on average) with low false positive rates. Feature importance analysis (Gini decrease and hidden layer weights) suggest that Pb, As, U, Sr, Eu, Mn, and Fe are the important parameters. Arsenic, U, Eu, Mn, and Fe are redox‐sensitive elements, with their concentrations responding to changes in fluid redox conditions. Strontium primarily originates from the breakdown of plagioclase, which is more likely to occur under oxidizing fluid conditions. Therefore, we infer that the main controlling factor of the models is the redox conditions. The two distinct models consistently highlight the most significant contribution of Pb to this differentiation, even though Pb is not a redox‐sensitive element and can only substitute for Ca2+ in apatite as Pb2+. We infer that the high contribution of Pb may be attributed to the potential transportation of Au in the form of a Pb‐(Bi)‐Au melt, and the Pb content in apatite is influenced by the Pb content in the melt, fluid oxygen, and sulfur fugacity. We also propose a novel discriminant plot using Linear Discriminant Analysis (LDA) to assess the mineralization potential in quartz veins and alteration zones based on apatite trace element data. The machine learning and LDA results suggest that apatite trace elements could be used effectively in the future orogenic gold deposit exploration.

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Newly-recognized Triassic highly fractionated leucogranite in the Koktokay deposit (Altai, China): Rare-metal fertility and connection with the No. 3 pegmatite

Shen

Pan²,

Li³

et al. 2022

Gondwana Research

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Geochemical characteristics and significance of apatite from the Koktokay pegmatitic rare-metal deposit, Altay, Xinjiang

Cited by 6 publications

References 64 publications

U–Pb Dating, Gemology, and Chemical Composition of Apatite from Dara-e-Pech, Afghanistan

U–Pb Dating, Gemology, and Chemical Composition of Apatite from Dara-e-Pech, Afghanistan

Primary Controlling Factors of Apatite Trace Element Composition and Implications for Exploration in Orogenic Gold Deposits

Newly-recognized Triassic highly fractionated leucogranite in the Koktokay deposit (Altai, China): Rare-metal fertility and connection with the No. 3 pegmatite

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