Mantle exhumation at magma-poor rifted margins controlled by frictional shear zones

Theunissen, Thomas; Huismans, Ritske S.

doi:10.1038/s41467-022-29058-1

Cited by 13 publications

(13 citation statements)

References 70 publications

(115 reference statements)

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“…These are partially explained because our models are generic, that is, not created to reproduce any specific basin, and because they are 2D and continental rifting and salt flow are essentially 3D processes with significant lateral variability in dynamics and geometries (Brune et al., 2014, 2018; Duclaux et al., 2020; M. P. Jackson & Hudec, 2017; Pichel et al., 2022). Rifting can also involve additional processes not modeled here, such as syn‐rift magmatism (e.g., intrusives and SDRs), underplating, hydrothermal activity, and mantle exhumation (cf., Ros et al., 2017; Sapin et al., 2021; Lu & Huismans, 2022; Theunissen & Huismans, 2022). These processes can impact the architecture, rheology, and thermal state of rifted margins and consequently influence salt deposition, its mobility and salt flow.…”

Section: Discussionmentioning

confidence: 99%

Coupling Crustal‐Scale Rift Architecture With Passive Margin Salt Tectonics: A Geodynamic Modeling Approach

et al. 2022

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Continental rifting and breakup are a product of the extension and thinning of the lithosphere and ocean floor spreading (McKenzie, 1978). The style of rifting and margin architecture is generally controlled by the rheology and overall composition of the crust and mantle lithosphere. Strong crust favors narrow rifting whereas weak crust promotes formation of wide rifted margins (Buck, 1991;Huismans & Beaumont, 2011. Other factors such as the lithospheric thermal state and thickness, inheritance and temporal and spatial variations in rifting kinematics also influence rifted margin architecture (

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Section: Discussionmentioning

confidence: 99%

Coupling Crustal‐Scale Rift Architecture With Passive Margin Salt Tectonics: A Geodynamic Modeling Approach

et al. 2022

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“…The program GeoFLAC (FLAC stands for Fast Lagrangian Analysis of Continua) has been a useful tool for researchers for the past three decades by providing a means to explore the rheological, petrological, thermal, and kinematic evolution of rifting (Davis & Lavier, 2017;Detournay & Hart, 1999;Geoffroy et al, 2015;Poliakov et al, 1993). Recent work using geodynamic modelling purports to show that doming and exhumation of mantle peridotite via out-of-sequence detachments is the result of a "strength competition" between weak, frictional-plastic shear zones and thermal weakening beneath the necking domain of a continental rift (Theunissen & Huismans, 2022). Theunissen & Huismans (2022) also suggest that the mode of deformation is a consequence of varying extension rate and fault strength.…”

Section: Methods Justificationmentioning

confidence: 99%

“…Recent work using geodynamic modelling purports to show that doming and exhumation of mantle peridotite via out-of-sequence detachments is the result of a "strength competition" between weak, frictional-plastic shear zones and thermal weakening beneath the necking domain of a continental rift (Theunissen & Huismans, 2022). Theunissen & Huismans (2022) also suggest that the mode of deformation is a consequence of varying extension rate and fault strength. Ruh et al (2021) invoke dynamic grain recrystallization as a key process of lithospheric rupture in their own numerical modeling work.…”

Section: Methods Justificationmentioning

confidence: 99%

Mantle Deformation Processes during the Rift-to-Drift Transition at Magma-Poor Margins

Montiel¹,

Masini²,

Lavier

et al. 2023

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The rift-to-drift transition at rifted margins is an area of active investigation due to unresolved issues of the ocean-continent transition (OCT). Deep structures that characterize modern OCTs are often difficult to identify by seismic observations, while terrestrial exposures are preserved in fragments separated by tectonic discontinuities. Numerical modeling is a powerful method for contextualizing observations within rifted margin evolution. In this article, we synthesize geological observations from fossil ocean-continent transitions preserved in ophiolites, a recent seismic experiment on the Ivorian Margin of West Africa, and GeoFLAC models to characterize mantle deformation and melt production for magma-poor margins. Across varied surface heat fluxes, mantle potential temperatures, and extension rates our model results show important homologies with geological observations. We propose that the development of large shear zones in the mantle, melt infiltration, grain size reduction, and anastomosing detachment faults control the structure of OCTs. We also infer through changes in fault orientation that upwelling, melt-rich asthenosphere is an important control on the local stress environment. During the exhumation phase of rifting, continentward-dipping shear zones couple with seaward-dipping detachment faults to exhume the subcontinental and formerly asthenospheric mantle. The mantle forms into core-complex-like domes of peridotite at or near the surface. The faults that exhume these peridotite bodies are largely anastomosing and exhibit magmatic accretion in their footwalls. A combination of magmatic accretion and volcanic activity derived from the shallow melt region constructs the oceanic lithosphere in the footwalls of the out-of-sequence, continentward-dipping detachment faults in the oceanic crust and subcontinental mantle.

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“…Oceanic crust keeps the same rheology, i.e. fully frictionally weakened material to avoid strain localization (e.g., Theunissen and Huismans, 2022).…”

Section: Melt Prediction and Related Feedback On Mantle Densitiesmentioning

confidence: 99%

“…S13). For mantle rocks, we use ϕ eff (ε 1 ) = 4 • and the cohesion is kept constant with C eff (ε 1 ) = 20MPa (Theunissen and Huismans, 2022). The sub-lithospheric mantle is fully plastically weakened when exhumed inhibiting strain localization and ensuring a symmetric spreading and a smooth relief at the sea-floor.…”

Section: A2 Rheologymentioning

confidence: 99%

Relative continent/mid-ocean ridge elevation: a reference case for isostasy in geodynamics

Theunissen¹,

Huismans²,

Lü³

et al. 2022

Preprint

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<p>The choice of crustal and mantle densities in numerical geodynamic models is usually based on convention. The isostatic component of the topography is, however, in most if not all cases not calibrated to fit observations resulting in not very well constrained elevations. The density distribution on Earth is not easy to constrain because it involves multiple variables (temperature, pressure, composition, and deformation). We provide a review and global analysis of the topography of the Earth showing that elevation of stable continents and active mid-ocean ridges far from hotspots on average is +400 m and -2750 m respectively. We show that density values for the crust and mantle, commonly used for isostatic modeling result in highly inaccurate prediction of topography. We use thermodynamic calculations to constrain the density distribution of the continental lithospheric mantle, sub-lithospheric mantle, the mid-ocean ridge mantle, and review data on crustal density. We couple the thermo-dynamic consistent density calculations with 2-D forward geodynamic modelling including melt prediction and calibrate crustal and mantle densities that match the observed elevation difference. Our results can be used as a reference case for geodynamic modeling that accurately fits the relative elevation between continents and mid-ocean ridges consistent with geophysical observations and thermodynamic calculations.&#160;</p>

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Mantle exhumation at magma-poor rifted margins controlled by frictional shear zones

Cited by 13 publications

References 70 publications

Coupling Crustal‐Scale Rift Architecture With Passive Margin Salt Tectonics: A Geodynamic Modeling Approach

Coupling Crustal‐Scale Rift Architecture With Passive Margin Salt Tectonics: A Geodynamic Modeling Approach

Mantle Deformation Processes during the Rift-to-Drift Transition at Magma-Poor Margins

Relative continent/mid-ocean ridge elevation: a reference case for isostasy in geodynamics

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