Paleoproterozoic metamorphic and deformation history of the Thompson Nickel Belt, Superior Boundary Zone, Canada, from in situ U–Pb analysis of monazite

Couëslan, Chris G.; Pattison, David R.M.; DuFrane, S. Andrew

doi:10.1016/j.precamres.2013.06.009

Cited by 10 publications

(5 citation statements)

References 47 publications

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“…This broad ca. 56 Myr interval is consistent with metamorphic ages peripheral to the LLGB, 193 which define peak metamorphism at 1.81-1.80 Ga and a cryptic secondary metamorphic event and/or 194 thermal pulse at 1.79-1.78 Ga (Couëslan et al, 2013;Schneider et al, 2007). Evidence for earlier regional 195 metamorphic ages have been reported elsewhere in the Reindeer Zone (e.g., ca.…”

supporting

confidence: 63%

Sedimentary basin controls on orogenic gold deposits: New constraints from U-Pb detrital zircon and Re-Os sulphide geochronology, Lynn Lake greenstone belt, Canada

Lawley

Yang

Selby

et al. 2020

Ore Geology Reviews

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supporting

confidence: 63%

Sedimentary basin controls on orogenic gold deposits: New constraints from U-Pb detrital zircon and Re-Os sulphide geochronology, Lynn Lake greenstone belt, Canada

Lawley

Yang

Selby

et al. 2020

Ore Geology Reviews

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“…In the western part of the belt where BT and TH are located, the rocks are dominated by 2.2 -2.0 Ga serpentinized ultramafic rocks, metagabbros, amphibolites, gneisses, schists, skarns, and quartzites (Hulbert et al, 2005; 9 Zwanzig et al, 2007). The rocks experienced a series of metamorphic events during 1850 -1750 Ma (Couëslan et al, 2013) with peak metamorphic temperatures of ~ 700 ºC in the Thompson area (Paktunҫ, 1984). Later (not yet dated) low-temperature (250 -300 ºC) alteration of rocks at Thompson by chloride-rich fluid is evidenced by the PGE-Au-As mineralization (Chen et al, 1993).…”

Section: Geological Background and Samplesmentioning

confidence: 99%

N2 in deep subsurface fracture fluids of the Canadian Shield: Source and possible recycling processes

Giunta

et al. 2021

Chemical Geology

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In addition to high concentrations of CH4 and H2, abundant dissolved N2 is found in subsurface fracture fluids in Precambrian cratons around the world. These fracture fluids have hydrogeological isolation times on order of thousands to millions and even billions of years. Assessing the sources and sinks of N2 and related (bio)geochemical processes that drive the nitrogen cycle in these long isolated systems can shed insights into the nitrogen cycles on early Earth with implications for other planets and moons. In this study, we collected dissolved gas samples from deep subsurface fracture fluids at seven sites (Kidd Creek, LaRonde, Nickel Rim, Fraser, Copper Cliff South, Thompson, and Birchtree) in the Canadian Shield. Multiple gas components (e.g., H2, O2 and Ar) were integrated with δ 15 NN2 values to characterize the N2 signatures. Results show that the dissolved N2 in deep subsurface fracture fluids from the Canadian Shield sites are more 15 N-enriched than those from the Fennoscandian Shield and the Witwatersrand Basin in the Kaapvaal Craton. The nitrogen isotopic signatures of the Canadian Shield samples coupled with their hydrogeological framework indicate the N2 was sourced from fixed ammonium in silicate minerals in host rocks and was generated by metamorphic devolatilization.Modeling of nitrogen devolatilization from host rocks supports this interpretation, but also suggests that a second process, likely abiotic N2 reduction, is required to account for the observed 15 N enrichment in the N2 samples from the Canadian Shield. A 10-year monitoring study for one of the boreholes, at 2.4 km of the Kidd Creek Observatory, shows a steady decrease in 15 NN2 values with time, which coincides with the temporal isotopic evolution of some other gas components in this borehole. Although it cannot be confirmed at this time, this isotopic shift in N2 may be potentially attributed to microbial processes (e.g., anaerobic oxidation of ammonium). Nevertheless, the large 15 N enrichments for the majority of the samples in this study suggest that the nitrogen cycle in the deep saline fracture fluids in the Canadian Shield is dominated by abiotic processes. This is in contrast to the nitrogen cycles in the subsurface fracture fluids in the Fennoscandian Shield and the Witwatersrand Basin, which have been shown to be strongly affected by extant microbial ecosystems discovered in those fracture waters.

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“…This core may be the result of secondary alteration, but the oscillatory zoning that parallels its boundaries suggests it may be a primary feature. Oscillatory-zoned monazite is also reported primarily from igneous and/or fluid-rich systems (e.g., [12,13,[64][65][66]). In both cases, its composition reflects local feedback between the monazite's growth surface and the fluid supply of elements (e.g., [64]).…”

Section: Evidence For Hydrothermal Originmentioning

confidence: 99%

“…Fluorapatite is common in the Llallagua mine [5,6,15], and some have speculated that the presence of F in the Llallagua monazite may be due in part of the decomposition of fluorapatite during the final stages of hydrothermal deposition [6,66,76]. Phosphates suggested to form during the dissolution of apatite include wavellite, paravauxite, and childrenite [6].…”

Section: Insight From Compositional Datamentioning

confidence: 99%

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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Paleoproterozoic metamorphic and deformation history of the Thompson Nickel Belt, Superior Boundary Zone, Canada, from in situ U–Pb analysis of monazite

Cited by 10 publications

References 47 publications

Sedimentary basin controls on orogenic gold deposits: New constraints from U-Pb detrital zircon and Re-Os sulphide geochronology, Lynn Lake greenstone belt, Canada

Sedimentary basin controls on orogenic gold deposits: New constraints from U-Pb detrital zircon and Re-Os sulphide geochronology, Lynn Lake greenstone belt, Canada

N2 in deep subsurface fracture fluids of the Canadian Shield: Source and possible recycling processes

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

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