Hf isotopes in zircon from the western Superior province, Canada: Implications for Archean crustal development and evolution of the depleted mantle reservoir
U-Pb and Hf isotopic measurements on zircons from the western Superior province confirm that the area contains at least three distinct terrane types. Juvenile terranes that formed mostly within the time span 2.75-2.68 Ga occupy much of the western Wabigoon subprovince as well as granite-greenstone b...
| Published in: | Precambrian Research |
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| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | unknown |
| Published: |
Elsevier
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| Subjects: | |
| Online Access: | http://hdl.handle.net/1885/36496 https://doi.org/10.1016/j.precamres.2005.07.005 https://openresearch-repository.anu.edu.au/bitstream/1885/36496/5/46_2005_Don_Davis_Western_Superior_Hf_PrecambRes.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/36496/7/01_Davis_Hf_isotopes_in_zircon_from_the_2005.pdf.jpg |
| Summary: | U-Pb and Hf isotopic measurements on zircons from the western Superior province confirm that the area contains at least three distinct terrane types. Juvenile terranes that formed mostly within the time span 2.75-2.68 Ga occupy much of the western Wabigoon subprovince as well as granite-greenstone belts to the south. Juvenile 3.0 Ga terranes that were reworked over the time span 2.7-3.0 Ga occupy the south-central part of the Wabigoon subprovince and the North Caribou block in the Sachigo subprovince. Rocks with mantle extraction ages as old as 3.5 Ga and zircon U-Pb ages extending to 3.3 Ga characterize a third type of terrane represented by the Winnipeg River subprovince. This terrane was strongly reworked during the late Archean. Arc-related magmatism was ongoing at 2.71-2.75 Ga in the different terranes, which probably accreted over the time span 2.71-2.68 Ga. Enriched Hf and high O isotopic signatures in late sanukitoid-suite plutons appear to be correlated, which suggests that assimilation of Mesoarchean crust was an important factor in their magmatic evolution. Enriched Hf isotopic signatures in detrital and igneous zircon from parts of the north-central Wabigoon subprovince support previous suggestions that the Winnipeg River terrane extends eastward beyond the Winnipeg River subprovince. The Winnipeg River subprovince was probably being uplifted and eroded into the Quetico sedimentary basin shortly after 2700 Ma, as shown by detrital zircons with enriched Hf isotopic signatures and Meso- to Paleoarchean ages. The pattern of ages and isotopic signatures from the North Caribou block and the south-central Wabigoon subprovince are similar, suggesting that these terranes are correlative. If so, the south-central Wabigoon terrane may have been tectonically transported from the north. Hf isotopic compositions of zircon from juvenile Archean sources are remarkably consistent and define an average εHf value of +3.5 ± 0.2 for samples with an average age of 2724 Ma and a best estimate of +2.7 ± 0.4 at 3000 Ma. ... |
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