U–Pb SHRIMP geochronology of Th-poor, hydrothermal monazite: An example from the Llallagua tin-porphyry deposit, Bolivia

Kempe, Ulf; Lehmann, Bernd; Wolf, D.; Родионов, Н. В.; Bombach, Klaus; Schwengfelder, U.; Dietrich, A.

doi:10.1016/j.gca.2008.05.059

Cited by 59 publications

(19 citation statements)

References 74 publications

(146 reference statements)

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“…The region was once considered one of the largest hard-rock tin deposits in the world, and produced more than 0.5 million tons of metallic tin [3][4][5][6][7]. The richest ore deposits are located within a zone where the belt makes a sharp curve ( Figure 1) and are commonly found in association with intrusive igneous rocks [1,2,[4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…The mineral occurs as prismatic or pyramidal crystals with contact or penetration twinning [6]. The Llallagua monazite is also known for oscillatory zoning in backscattered electrons (BSE) (Figure 2) [7,11]. This type of zoning is considered rare for the mineral, which is more commonly seen as sector zoned in BSE [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

“…[16]. Inset shows the location of the mining district within the tin belt of Bolivia, Peru, and Argentina after [7]. .…”

Section: Introductionmentioning

confidence: 99%

“…Geological map and cross-section of the La Joya mining district after [16]. Inset shows the location of the mining district within the tin belt of Bolivia, Peru, and Argentina after [7]. The origin of the Bolivian tin belt is suggested to be a series of compressional events between the Farallon/Nazca oceanic plate and the South American continent, which generated peraluminous magmas that equilibrated with graphite-rich, metapelitic sources [4,17].…”

Section: Introductionmentioning

confidence: 99%

“…Monazite from the Llallagua deposit contains minor Th, U [5,7,11,15,20] and up to 99.9% common 206 Pb [7]. Monazite is thought to exclude common Pb during crystallization (e.g., [20][21][22][23]).…”

Section: Introductionmentioning

confidence: 99%

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Speculations Linking Monazite Compositions to Origin: Llallagua Tin Ore Deposit (Bolivia)

Catlos

Miller

2017

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Monazite [(Ce,Th)PO 4 ] from the Llallagua tin ore deposit in Bolivia is characterized by low radiogenic element contents. Previously reported field evidence and mineral associations suggest the mineral formed via direct precipitation from hydrothermal fluids. Monazite compositions thus may provide insight into characteristics of the fluids from which it formed. Chemical compositions of three Llallagua monazite grains were obtained using Electron Probe Microanalysis (EPMA, n = 64) and laser ablation mass spectrometry (LA-ICP-MS, n = 56). The mineral has higher amounts of U (123 ± 17 ppm) than Th (39 ± 20 ppm) (LA-ICP-MS, ±1σ). Grains have the highest amounts of fluorine ever reported for monazite (0.88 ± 0.10 wt %, EPMA, ±1σ), and F-rich fluids are effective mobilizers of rare earth elements (REEs), Y, and Th. The monazite has high Eu contents and positive Eu anomalies, consistent with formation in a highly-reducing back-arc environment. We speculate that F, Ca, Si and REE may have been supplied via dissolution of pre-existing fluorapatite. Llallagua monazite oscillatory zoning is controlled by an interplay of low (P + Ca + Si + Y) and high atomic number (REE) elements. We suggest monazite compositions provide insight into fluid geochemistry, mineral reactions, and tectonic settings of ore deposits that contain the mineral.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…[16]. Inset shows the location of the mining district within the tin belt of Bolivia, Peru, and Argentina after [7]. .…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Speculations Linking Monazite Compositions to Origin: Llallagua Tin Ore Deposit (Bolivia)

Catlos

Miller

2017

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U–Pb Dating of Mineral Deposits: From Age Constraints to Ore-Forming Processes

Chelle-Michou

Schaltegger

2023

Mineral Resource Reviews

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The timing and duration of ore-forming processes are amongst the key parameters required in the study of mineral systems. After more than a century of technical developments, innovations and investigation, the U–Pb system arguably is the most mature radioisotopic system in our possession to conduct absolute dating of a wide range of minerals across geological environments and metallogenic processes. Here, we review the basics of U–Pb geochronology, the key historic developments of the method, and the most commonly used analytical techniques (including data reduction, Pb-correction, uncertainty propagation and data presentation) and minerals while pointing out their respective advantages, weaknesses and potential pitfalls. We also highlight critical aspects that need to be considered when interpreting a date into the age of a geological process (including field and petrographic constraints, open-system behavior, handling and interpretation of uncertainties). While U–Pb geochronology is strongly biased toward zircon dating, we strive to highlight the great diversity of minerals amenable to U–Pb dating (more than 16 mineral species) in the context of mineral systems, and the variety of geological events they can potentially date (magmatism, hydrothermal activity, ore-formation, cooling, etc.). Finally, through two case studies we show (1) how multi-mineral geochronological studies have been used to bracket and decipher the age of multiple geological events associated with the world-class Witwatersrand gold province, and (2) how rather than the absolute age, the duration and rate of the mineralizing event at porphyry copper deposits opens new avenues to understand ore-forming processes and the main controls on the size of such deposits. The improving precision, accuracy and spatial resolution of analyses in tandem with high-quality field and petrographic observations, numerical modelling and geochemical data, will continue to challenge paradigms of ore-forming processes and contribute significant breakthroughs in ore deposit research and potentially to the development of new exploration tools.

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Timing and genesis of Cu–(Au) mineralization in the Khetri Copper Belt, northwestern India: constraints from in situ U–Pb ages and Sm–Nd isotopes of monazite-(Ce)

Zhou

Williams‐Jones

et al. 2018

Miner Deposita

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The Khetri Copper Belt (KCB) in northwestern India contains a number of economically important IOCG-like Cu-(Au) deposits hosted in Proterozoic meta-sedimentary rocks. They comprise massive, vein-type and disseminated replacement ores with monazite-(Ce) locally present. In this study, in-situ U-Pb ages and Sm-Nd isotopic compositions of monazite-(Ce) were obtained, in order to constrain the timing of mineralization, and to trace the sources of the ore metals. Monazite-(Ce) crystals were identified in two representative deposits in the KCB, Madhan-Kudhan and Kolihan. In the Madhan-Kudhan deposit, monazite-(Ce) crystals from both ores and ore-hosting rocks are intimately intergrown or texturally associated with hydrothermal minerals (e.g., pyrrhotite, chalcopyrite and biotite), and are interpreted to have a hydrothermal origin. The hydrothermal monazite-(Ce) crystals have U-Pb ages of 833 ± 5 to 837 ± 6 Ma, which represent the timing of the mineralization in the Madhan-Kudhan deposit. Two types of monazite-(Ce) crystals were observed in the sample of the Kolihan deposit. Type 1 monazite-(Ce) crystals occur in close spatial association with sulfide minerals, indicating a hydrothermal origin. Uranium-lead dating of these monazite-(Ce) crystals yielded an age of 840 ± 6 Ma, which is indistinguishable from the U-Pb ages of hydrothermal monazite-(Ce) from the Madhan-Kudhan deposit. Type 2 monazite-(Ce) crystals are enclosed by sulfide minerals, and commonly show concentric zonation with respect to ThO2 (0.45 to 13.59 wt.%). They yielded a weighted average 207 Pb/ 206 Pb age of 1362 ± 29 Ma and an upper concordia intercept age of 1357 ± 30 Ma, which may record a pre-ore metamorphic event in the KCB. Hydrothermal monazite-(Ce) crystals have εNd(t=835Ma) values ranging from -4.3 to -16.8, indicating the incorporation in the ore-forming systems of a range of upper crustal materials with different isotopic signatures.The mineralization ages of the Cu-(Au) deposits in the KCB fall within the overall age-ranges of the regional post-collisional igneous activity (~800 to ~880 Ma) and Ca-Na metasomatism (~830 to ~850 Ma). Combining this temporal association with related geochemical and isotopic data, we propose that the Neoproterozoic

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U–Pb SHRIMP geochronology of Th-poor, hydrothermal monazite: An example from the Llallagua tin-porphyry deposit, Bolivia

Cited by 59 publications

References 74 publications

Speculations Linking Monazite Compositions to Origin: Llallagua Tin Ore Deposit (Bolivia)

Speculations Linking Monazite Compositions to Origin: Llallagua Tin Ore Deposit (Bolivia)

U–Pb Dating of Mineral Deposits: From Age Constraints to Ore-Forming Processes

Timing and genesis of Cu–(Au) mineralization in the Khetri Copper Belt, northwestern India: constraints from in situ U–Pb ages and Sm–Nd isotopes of monazite-(Ce)

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