No evidence of supracrustal recycling in Si-O isotopes of Earth's oldest rocks 4 Ga ago

Identifying the oldest evidence for the recycling of hydrated crust into magma on Earth is important because it is most effectively achieved by subduction. However, given the sparse geological record of early Earth, the timing of first supracrustal recycling is controversial. Silicon and oxygen isot...

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Bibliographic Details
Published in:Science advances 2023-06, Vol.9 (26), p.eadf0693-eadf0693
Main Authors: Zhang, Qing, Zhao, Lei, Zhou, Dawn, Nutman, Allen P, Mitchell, Ross N, Liu, Yu, Li, Qiu-Li, Yu, Hui-Min, Fan, Billy, Spencer, Christopher J, Li, Xian-Hua
Format: Article
Language:English
Subjects:
Canada
Earth, Environmental, Ecological, and Space Sciences
Earth, Planet
Geochemistry
Geology
Oxygen Isotopes
SciAdv r-articles
Silicon
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Summary:Identifying the oldest evidence for the recycling of hydrated crust into magma on Earth is important because it is most effectively achieved by subduction. However, given the sparse geological record of early Earth, the timing of first supracrustal recycling is controversial. Silicon and oxygen isotopes have been used as indicators of crustal evolution on Archean igneous rocks and minerals to trace supracrustal recycling but with variable results. We present Si-O isotopes of Earth's oldest rocks [4.0 billion years ago (Ga)] from the Acasta Gneiss Complex, northwest Canada, obtained using multiple techniques applied to zircon, quartz, and whole rock samples. Undisturbed zircon is considered the most reliable recorder of primary Si signatures. By combining reliable Si isotope data from the Acasta samples with filtered data from Archean rocks globally, we observe that widespread evidence for a heavy Si signature is recorded since 3.8 Ga, marking the earliest record of surface silicon recycling.
ISSN:2375-2548
2375-2548
DOI:10.1126/sciadv.adf0693