Vastly Different Heights of LLVPs Caused by Different Strengths of Historical Slab Push

Yuan, Qian; Li, Mingming

doi:10.1029/2022gl099564

Cited by 8 publications

(3 citation statements)

References 79 publications

(132 reference statements)

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“…Cases with different rheologies show that a smaller viscosity of the LLSVPs (Figures S1a in Supporting Information ), a larger reference viscosity (Figures S1b in Supporting Information ), and a more strongly temperature‐dependent viscosity (Figures S1c in Supporting Information ) do not significantly alter the plume‐induced subduction process, except for the onset time (77–320 Myr)—in general, higher mantle viscosity leads to later plume‐induced subduction initiation. We considered cases with lower (Figures S1d in Supporting Information ) and higher (Figures S1e in Supporting Information ) LLSVP density than the reference case, as in our earlier work (Yuan and Li, 2022a, 2022b), as well as a more compressible (more depth‐dependent density) LLSVP case (Figures S1f in Supporting Information ). We find the overall dynamics of these computations closely resemble those of the reference case.…”

Section: Resultsmentioning

confidence: 99%

A Giant Impact Origin for the First Subduction on Earth

Yuan,

Gurnis,

Asimow

et al. 2024

Geophysical Research Letters

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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.

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Section: Resultsmentioning

confidence: 99%

A Giant Impact Origin for the First Subduction on Earth

Yuan,

Gurnis,

Asimow

et al. 2024

Geophysical Research Letters

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“…The radial temperature profile in the case of thermochemical convection is taken from prior studies (Mao & Zhong, 2019; Zhang et al., 2010). In addition, we tested a model in which we consider the effect of higher viscosity (10 times higher than the ambient mantle) in addition to the higher density of the thermochemical layer, as suggested by previous studies (Heyn et al., 2018; McNamara & Zhong, 2004; Yuan & Li, 2022). The intrinsic density and viscosity stabilize the chemical piles and prevent them from being entrained and churned into the ambient mantle, which can explain their stability for more than 250 Myrs.…”

Section: Methodsmentioning

confidence: 99%

How the Indian Ocean Geoid Low Was Formed

Pal

Ghosh

2023

Geophysical Research Letters

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The origin of the Earth's lowest geoid, the Indian Ocean geoid low (IOGL) has been controversial. The geoid predicted from present‐day tomography models has shown that mid to upper mantle hot anomalies are integral in generating the IOGL. Here we assimilate plate reconstruction in global mantle convection models starting from 140 Ma and show that sinking Tethyan slabs perturbed the African Large Low Shear Velocity province and generated plumes beneath the Indian Ocean, which led to the formation of this negative geoid anomaly. We also show that this low can be reproduced by surrounding mantle density anomalies, without having them present directly beneath the geoid low. We tune the density and viscosity of thermochemical piles at core‐mantle boundary, Clapeyron slope and density jump at 660 km discontinuity, and the strength of slabs, to control the rise of plumes, which in turn determine the shape and amplitude of the geoid low.

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“…However, it has been argued that LLVPs could only have remained stable beyond ∼300 million years in the past if they were able to withstand impingement by downgoing slabs (e.g., Wolf & Evans, 2022). Other studies have argued that the shape of low velocity anomalies is controlled by downgoing slabs and that they evolve over time (e.g., McNamara, 2019; Yuan & Li, 2022; Zhong et al., 2007; Zhong & Rudolph, 2015). This notion agrees with inferences, based on seismic tomography, that plumes occur where slabs do not suppress them, which is not necessarily (always) spatially coincident with LLVP edges (Davaille & Romanowicz, 2020).…”

Section: Open Science Questions That Deep Mantle Anisotropy Studies C...mentioning

confidence: 99%

Advances in Mapping Lowermost Mantle Convective Flow With Seismic Anisotropy Observations

Wolf,

Li,

Long

et al. 2024

Reviews of Geophysics

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Convective flow in the deep mantle controls Earth's dynamic evolution, influences plate tectonics, and has shaped Earth's current surface features. Present and past convection‐induced deformation manifests itself in seismic anisotropy, which is particularly strong in the mantle's uppermost and lowermost portions. While the general patterns of seismic anisotropy have been mapped for the upper mantle, anisotropy in the lowermost mantle (called D′′) is at an earlier stage of exploration. Here we review recent progress in methods to measure and interpret D′′ anisotropy. Our understanding of the limitations of existing methods and the development of new measurement strategies have been aided enormously by the availability of high‐performance computing resources. We give an overview of how measurements of seismic anisotropy can help constrain the mineralogy and fabric of the deep mantle. Specifically, new and creative strategies that combine multiple types of observations provide much tighter constraints on the geometry of anisotropy than have previously been possible. We also discuss how deep mantle seismic anisotropy provides insights into lowermost mantle dynamics. We summarize what we have learned so far from measurements of D′′ anisotropy, how inferences of lowermost mantle flow from measurements of seismic anisotropy relate to geodynamic models of mantle flow, and what challenges we face going forward. Finally, we discuss some of the important unsolved problems related to the dynamics of the lowermost mantle that can be elucidated in the future by combining observations of seismic anisotropy with geodynamic predictions of lowermost mantle flow.

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Vastly Different Heights of LLVPs Caused by Different Strengths of Historical Slab Push

Cited by 8 publications

References 79 publications

A Giant Impact Origin for the First Subduction on Earth

A Giant Impact Origin for the First Subduction on Earth

How the Indian Ocean Geoid Low Was Formed

Advances in Mapping Lowermost Mantle Convective Flow With Seismic Anisotropy Observations

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