Provenance of Siliclastic Sedimentary Rocks in the Eastern Portion of the North Caribou Greenstone Belt
The Zeemal Heaton Lake metasedimentary assemblage comprises ~50% of the eastern limb of the North Caribou greenstone belt, which hosts the Musselwhite gold deposit (~ 5.4 Moz Au). The metasedimentary assemblage is divided into two based on their distribution: the Central-belt and North-rim of the be...
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| Language: | en |
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Université d'Ottawa / University of Ottawa
2017
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| Online Access: | http://hdl.handle.net/10393/36115 http://dx.doi.org/10.20381/ruor-20395 |
| Summary: | The Zeemal Heaton Lake metasedimentary assemblage comprises ~50% of the eastern limb of the North Caribou greenstone belt, which hosts the Musselwhite gold deposit (~ 5.4 Moz Au). The metasedimentary assemblage is divided into two based on their distribution: the Central-belt and North-rim of the belt. The Zeemal Heaton Lake metasedimentary rocks have been interpreted to represent a turbidite succession, consisting of pelite, arkose, wacke and conglomerate. Detrital U-Pb zircon age populations from this study indicate variable sources in the Central-belt metasediments with a maximum age of deposition of 2798.8 ± 29 Ma, while metasediments along the North portion of the limb display a maximum age of deposition of 2696 ± 39 Ma. This indicates the likelihood of two discrete basins with the Zeemal Heaton Lake assemblage.
Neodymium isotopic values for the sedimentary rocks along the North-rim of the belt display εNd2680Ma ranging from -1.2 to -0.9. An overlapping but slightly more evolved signature shown in the Central portion with values of εNd2800Ma -1.6 to 0.1. This indicates detritus for the Central-belt was likely sourced from the older (~2850 Ma), (tonalite-granodiorite) surrounding intrusions. The North-rim sediments were sourced (in part) from the younger (~2700 Ma) granitic intrusions and rhyolites. The surrounding batholiths display εNdt overlapping with North-rim sedimentary rocks, however, indicate significant contribution beyond these immediate surrounding batholiths, which may include older mafic (2982 ± 0.8, 2870 ±2 Ma), younger rhyolitic unit (2723 ± 2 Ma) or more distal sources than the intrusions immediately adjacent to the belt.
Peak metamorphic mineral assemblages indicate a minimum of amphibolite facies-garnet zone or greater across the Central-belt portion of the greenstone belt. The North-rim metasediments display evidence for aureole metamorphism which may overprint earlier regional metamorphism. Nitrogen abundance and δ15N values of biotite of the Zeemal Heaton Lake metasedimentary assemblage indicate variable values than those associated with mineralization at the Musselwhite Mine, which is reported by Isaacs (2008). Mineralizing fluids from the Musselwhite mine have been interpreted by Issacs (2008) to be related to both metamorphic and magmatic fluids. Fluids associated with the Eyapamikama and/or Zeemal Heaton Lake metasediments appear to be metamorphic with minor magmatic influence near regional shear zones, but not directly related to the auriferous fluids which formed the Musselwhite mine. |
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