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Published May 16, 2024 | Published
Journal Article Open

A Giant Impact Origin for the First Subduction on Earth

  • 1. ROR icon California Institute of Technology

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

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).

Data Availability

The geodynamic code used in this work is available in Mansour et al. (2020). The model data on which this article is based are available at figshare (Yuan, 2024). The code used to make the figures can be accessed at Tian et al. (2023) and Ahrens et al. (2005).

Supporting Information S1

Files

Geophysical Research Letters - 2024 - Yuan - A Giant Impact Origin for the First Subduction on Earth.pdf

Additional details

Created:
May 31, 2024
Modified:
June 28, 2024