期刊
SCIENCE
卷 351, 期 6271, 页码 372-375出版社
AMER ASSOC ADVANCEMENT SCIENCE
DOI: 10.1126/science.aad5513
关键词
-
资金
- NSF [EAR 0948549]
- Wylie Fellowship
- Directorate For Geosciences
- Division Of Earth Sciences [0948549] Funding Source: National Science Foundation
The Archean Eon witnessed the production of early continental crust, the emergence of life, and fundamental changes to the atmosphere. The nature of the first continental crust, which was the interface between the surface and deep Earth, has been obscured by the weathering, erosion, and tectonism that followed its formation. We used Ni/Co and Cr/Zn ratios in Archean terrigenous sedimentary rocks and Archean igneous/metaigneous rocks to track the bulk MgO composition of the Archean upper continental crust. This crust evolved from a highly mafic bulk composition before 3.0 billion years ago to a felsic bulk composition by 2.5 billion years ago. This compositional change was attended by a fivefold increase in the mass of the upper continental crust due to addition of granitic rocks, suggesting the onset of global plate tectonics at similar to 3.0 billion years ago.
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