A Giant Impact Origin for the First Subduction on Earth
Abstract
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. It remains enigmatic how subduction could be initiated so soon after the presumably Moon-forming giant impact (MGI). Earlier studies found an increase in Earth's core-mantle boundary (CMB) temperature due to the accumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, with some of the impactor's mantle potentially surviving as the large low-shear velocity provinces (LLSVPs). Here, we show that a hot post-impact CMB drives the initiation of strong mantle plumes that can induce subduction initiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMB temperature is the primary factor triggering early subduction, with enrichment of heat-producing elements in LLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications for understanding the diverse tectonic regimes of rocky planets.
Copyright and License
© 2024. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Acknowledgement
We appreciate the constructive comments by Bradford Foley and an anonymous reviewer, as well as the editor's efficient handling of our study. Discussions with W. Mao, M. Li. H. Deng, J. Kegerreis, Y. Miyazaki, E. Asphaug are appreciated. Q. Yuan acknowledges support from the O.K. Earl Postdoctoral Fellowship at Caltech and partial support by the NSF through OCE-2049086 and EAR-2330810. We acknowledge use of the Anvil supercomputer at Purdue University supported by the NSF ACCESS program TG-EAR160027. Some figures in this study use the perceptually uniform color map “batlow” (Crameri et al., 2020).
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Additional details
- ISSN
- 1944-8007
- California Institute of Technology
- O. K. Earl Postdoctoral Fellowship
- National Science Foundation
- OCE‐2049086
- National Science Foundation
- EAR‐2330810
- National Science Foundation
- TG‐EAR160027
- Caltech groups
- Division of Geological and Planetary Sciences