In situ low-U garnet U-Pb dating by LA-SF-ICP-MS and its application in constraining the origin of Anji skarn system combined with Ar-Ar dating and Pb isotopes

Tang, Yanwen; Gao, Jianfeng; Lan, Ting-Guang; Cui, Kai; Han, Junjie; Zhang, Xue; Chen, You‐Wei; Chen, Yinghua

doi:10.1016/j.oregeorev.2020.103970

Cited by 37 publications

(21 citation statements)

References 47 publications

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“…The matrix effects can be minimized to improve the ages via different laser sampling rates, energy densities, crater diameters, and adding small amounts of N 2 , Q 2 , or H 2 O for non-matrix-matched and even matrix-matched methods. 5,17,22,28–30,32 In this study, when the spot size was fixed at 24 and 32 μm, increased laser sampling rate and energy density from 3 J (5 Hz) to 10 J (10 Hz) were obtained; without nitrogen, the age offsets of U–Pb and Th–Pb ages become smaller, i.e. , from 2.6% to 0.8% (Fig.…”

Section: Discussionmentioning

confidence: 62%

“…With increasing understanding and improvements in laser ablation systems, ion sources, and sample transports, non-matrix matched calibrations were applied successfully in the quantification of elements and U–Pb isotopes of dozens of ore and gangue minerals. 10,22,28–30,50,57 Furthermore, the matrix effect between wolframite and scheelite can be neglected nearly by the ratio-of-the-mean intensity method for data reduction in most analyzed conditions ( e.g. , different spot sizes, laser sampling rates, and energy densities).…”

Section: Discussionmentioning

confidence: 99%

“…Both the above methods belong to the non-matrix matched calibrations, which have increasingly successful applications in other different minerals, e.g. , zircon, 17 allanite, 18 monazite, 17 xenotime, 17 cassiterite, 19,20 garnet, 21,22 vesuvianite, 23 wolframite, 24,25 hematite, 26–28 ilmenite, 29 and scheelite. 30 However, due to the different ablation behavior between the different types of minerals, some special analytical conditions were applied to reduce the matrix effects, e.g.…”

Section: Introductionmentioning

confidence: 99%

“…31 Moreover, different laser sampling rates, energy densities, crater diameters, and ablation times were optimized to minimize the matrix effects and improve the ages. 5,10,17,22,28–30,32…”

Section: Introductionmentioning

confidence: 99%

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A new calibrated strategy for the in situ U–Th–Pb dating of bastnasite by xenotime

Tang

Liu

Yang

et al. 2022

J. Anal. At. Spectrom.

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Section: Discussionmentioning

confidence: 62%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A new calibrated strategy for the in situ U–Th–Pb dating of bastnasite by xenotime

Tang

Liu

Yang

et al. 2022

J. Anal. At. Spectrom.

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“…At present, it is impossible to carry out direct dating on magnetites, and therefore, the dating research on garnets can provide more direct constrains on the mineralization age due to their close spatial relationship with magnetites. Along with the development of laser ablation inductively coupled plasma-mass spectrometry (LA-ICPMS), in-situ garnet U-Pb isotope analysis has been gradually realized (Chen et al, 2016;Deng et al, 2017;Seman et al, 2017;Tang et al, 2021). As a main kind of skarn mineral, garnet has been used in dating research the skarn type deposits and yields accurate U-Pb ages (Deng et al, 2017;Li et al, 2018;Wafforn et al, 2018;Stifeeva et al, 2019;Duan et al, 2020;Tang et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Mineralization age and genesis of the makeng-style iron deposits in the Paleo-Pacific tectonic domain of South China: In situ LA-ICPMS garnet U-Pb chronological and geochemical constraints

Wang

Cao²,

Zhang³

et al. 2023

Front. Earth Sci.

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To reveal the genesis of Makeng-style iron polymetallic deposits from SE China in the paleo-Pacific tectonic domain, a new analytical method of LA-ICPMS garnet U-Pb dating and rare Earth element analysis was conducted for the Makeng, Luoyang, Dapai and Pantian deposits. The U-Pb dating results of nine garnet skarn samples from these deposits suggested that the Makeng-style iron polymetallic deposits mainly formed during 137–130 Ma, which is consistent with the zircon U-Pb and molybdenite Re-Os ages. This study provides more direct evidence of the mineralization age and the relationship between mineralization and granite, compared with previous studies on the zircon U-Pb dating for granites in the ore fields. Rare Earth element (REE) analysis results and REE patterns of four representative garnet samples from the Makeng, Luoyang, Dapai and Pantian deposits show that they are similar to typical skarn deposits, but obvious differences in the REE distribution types indicate that the ore-forming process may be distinct due to different mineralizing fluid for these Makeng-style deposits. Our new garnet U-Pb dating and rare Earth element analysis result not only provides new evidence for the mineralization age and genesis of the Makeng-style deposits but is also of great significance to promote the application of U-Pb dating methods to research skarn type deposits.

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Genesis of the Lamasu large skarn Cu deposit, northern Xinjiang: Constraints from garnet U–Pb dating, micro‐textural and geochemical analyses

Wang,

Liu,

Lai

et al. 2023

Geological Journal

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The Lamasu deposit is the first large copper (Cu) deposit with ~0.6 Mt Cu reserve in the Chinese Western Tianshan Orogen (NW China). The Cu orebodies are mainly hosted in the exoskarn of the Proterozoic Kusongmuqieke Group. Now, the metallogenic mechanism of newly discovered skarn Cu orebodies (0.5 Mt Cu) remains poorly constrained. In this study, we conducted LA‐ICP‐MS U–Pb isotope dating, EPMA and LA‐ICP‐MS geochemical analyses on different generations of garnet from Lamasu to elucidate the magmatic hydrothermal evolution and its timing. Garnets from the Lamasu exoskarn can be divided into three types: reddish‐brown coarse‐grained Grt‐I, light brown fine‐grained Grt‐II and yellowish‐green heterogranular Grt‐III, with U–Pb age of 389.1 ± 2.0 Ma, 387.1 ± 1.8 Ma and 387.0 ± 2.3 Ma, respectively. These dates represent the oldest Cu mineralization age in the Chinese Western Tianshan, coeval with the Middle Devonian subduction of the North Tianshan oceanic plate. Grt‐I to Grt‐III particles are mainly andradite with minor grossularite, and they have different REE compositions. The Grt‐I has total REE contents (∑REE) of 101.47 to 262.87 ppm, with steeply right‐inclining REE distribution patterns (LREE/HREE of 3.81 to 68.50) and positive Eu anomaly. The Grt‐II core has ∑REE of 163.49–249.52 ppm, LREE/HREE of 2.00–4.71, and negative Eu anomaly. The Grt‐II rim has ∑REE of 46.34–99.99 ppm, with LREE/HREE of 18.06–177.23, and positive Eu anomaly. The ∑REE of Grt‐III range from 31.71 to 219.02 ppm, with flat REE distribution pattern and positive Eu anomaly, and the LREE/HREE ranges from 2.16 to 9.07. These garnets have similar trace element compositions, featured by LILE‐depletions (e.g., Rb, Ba and Sr) and HFSE enrichments (e.g., Th, U, Nb and Ce). Micro‐texture and geochemical composition of garnets indicate that the Lamasu magmatic hydrothermal system could have changed from an open to a closed environment, and from infiltration metasomatism to diffusive metasomatism, which formed Grt‐I, Grt‐II and Grt‐III successively. These garnets generally formed in a relatively oxidized fluid environment, which inhibited early sulphide precipitation and favoured for Cu enrichment during the ore fluid evolution.

show abstract

In situ low-U garnet U-Pb dating by LA-SF-ICP-MS and its application in constraining the origin of Anji skarn system combined with Ar-Ar dating and Pb isotopes

Cited by 37 publications

References 47 publications

A new calibrated strategy for the in situ U–Th–Pb dating of bastnasite by xenotime

A new calibrated strategy for the in situ U–Th–Pb dating of bastnasite by xenotime

Mineralization age and genesis of the makeng-style iron deposits in the Paleo-Pacific tectonic domain of South China: In situ LA-ICPMS garnet U-Pb chronological and geochemical constraints

Genesis of the Lamasu large skarn Cu deposit, northern Xinjiang: Constraints from garnet U–Pb dating, micro‐textural and geochemical analyses

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