Viscous coupling at the lithosphere-asthenosphere boundary

Höink, Tobias; Jellinek, M.; Lenardic, Adrian

doi:10.1029/2011gc003698

Cited by 83 publications

(90 citation statements)

References 58 publications

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“…The assumption of a strong dehydrated lithosphere above a low-viscosity channel in the upper mantle allowed for channelization of lateral flow in the weak upper mantle [Höink et al, 2011]. Without channels, convective stresses driving failure would be smaller (see Figures 5 and 8 and Table 2, which show that decreasing channel thicknesses lead the systems from stagnant lid over episodic to plate tectonics).…”

Section: Channels Matter But Novel Causality Results Remain Robustmentioning

confidence: 99%

“…Our results support those ideas, and we did observe hot rising instabilities, from the lower thermal boundary layer, interacting with the upper boundary layer. We also observed that lateral temperature variations, in the low-viscosity upper mantle, could generate pressure gradients that drove lateral flow [Höink et al, 2011] and this, in turn, influenced upper boundary layer dynamics. Both of these effects are not consistent with the idea that the dynamics of the boundary layer are fully self determined.…”

Section: The Limits Of Self-determined Boundary Layer Dynamicsmentioning

confidence: 88%

“…So far, this observation is empirical. However, we note that in Höink et al [2011], an asthenosphere Rayleigh number that is inversely proportional to our channel number has been defined. This connection might allow in the future to develop a more solid theory around this observation.…”

Section: Channels Matter But Novel Causality Results Remain Robustmentioning

confidence: 99%

“…The active lithosphere drives shear flow in the lower viscosity upper mantle below the plate. During the stagnant phase, the velocity profiles show the signature of a pressure driven flow in the lower viscosity upper mantle [Höink et al, 2011].…”

Section: Increasing Basal Shear Stress Leads Into Plate Failurementioning

confidence: 99%

“…As it thickens into the low-viscosity upper mantle, pressure gradients are generated due to lateral temperature and associated density variations. The dynamics of this pressure driven flow, along with theoretical scalings calibrated against numerical experiments, are discussed in Höink et al [2011]. The velocity profiles document increasing basal shear stress, on the high-viscosity lithosphere, as the magnitude of pressure driven flow increases (Figure 4a).…”

Section: Increasing Basal Shear Stress Leads Into Plate Failurementioning

confidence: 99%

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The importance of temporal stress variation and dynamic disequilibrium for the initiation of plate tectonics

2016

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We use 1‐D thermal history models and 3‐D numerical experiments to study the impact of dynamic thermal disequilibrium and large temporal variations of normal and shear stresses on the initiation of plate tectonics. Previous models that explored plate tectonics initiation from a steady state, single plate mode of convection concluded that normal stresses govern the initiation of plate tectonics, which based on our 1‐D model leads to plate yielding being more likely with increasing interior heat and planet mass for a depth‐dependent Byerlee yield stress. Using 3‐D spherical shell mantle convection models in an episodic regime allows us to explore larger temporal stress variations than can be addressed by considering plate failure from a steady state stagnant lid configuration. The episodic models show that an increase in convective mantle shear stress at the lithospheric base initiates plate failure, which leads with our 1‐D model to plate yielding being less likely with increasing interior heat and planet mass. In this out‐of‐equilibrium and strongly time‐dependent stress scenario, the onset of lithospheric overturn events cannot be explained by boundary layer thickening and normal stresses alone. Our results indicate that in order to understand the initiation of plate tectonics, one should consider the temporal variation of stresses and dynamic disequilibrium.

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Section: Channels Matter But Novel Causality Results Remain Robustmentioning

confidence: 99%

Section: The Limits Of Self-determined Boundary Layer Dynamicsmentioning

confidence: 88%

Section: Channels Matter But Novel Causality Results Remain Robustmentioning

confidence: 99%

Section: Increasing Basal Shear Stress Leads Into Plate Failurementioning

confidence: 99%

Section: Increasing Basal Shear Stress Leads Into Plate Failurementioning

confidence: 99%

See 3 more Smart Citations

The importance of temporal stress variation and dynamic disequilibrium for the initiation of plate tectonics

2016

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Continental breakup and the dynamics of rifting in back-arc basins: The Gulf of Lion margin

et al. 2015

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Deep seismic profiles and subsidence history of the Gulf of Lion margin reveal an intense stretching of the distal margin and strong postrift subsidence, despite weak extension of the onshore and shallow offshore portions of the margin. We revisit this evolution from the geological interpretation of an unpublished multichannel seismic profile and other published geophysical data. We show that an 80 km wide domain of thin lower continental crust, the "Gulf of Lion metamorphic core complex," is present in the ocean-continent transition zone and exhumed mantle makes the transition with oceanic crust. The exhumed lower continental crust is bounded upward and downward by shallow north dipping detachments. The presence of exhumed lower crust in the deep margin explains the discrepancy between the amount of extension deduced from normal faults in the upper crust and total extension. We discuss the mechanism responsible for exhumation and present two scenarios: the first one involving a simple coupling between mantle extension due to slab retreat and crustal extension and the second one involving extraction of the lower crust and mantle from below the margin by the southeastward flow of hot asthenosphere in the back-arc region during slab rollback. In both scenarios, the combination of Eocene crustal thickening related to the Pyrenees, the nearby volcanic arc, and a shallow lithosphere-asthenosphere boundary weakened the upper mantle and lower crust enough to make them flow southeastward. The overall hot geodynamic environment also explains the subaerial conditions during most of the rifting stage and the delayed subsidence after breakup.

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Rapid South Atlantic spreading changes and coeval vertical motion in surrounding continents: Evidence for temporal changes of pressure-driven upper mantle flow

et al. 2014

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The South Atlantic region displays (1) a topographic gradient across the basin, with Africa elevated relative to South America, (2) a bimodal spreading history with fast spreading rates in Late Cretaceous and Eo‐Oligocene, and (3) episodic regional uplift events in the adjacent continents concentrated in Late Cretaceous and Oligocene. Here we show that these observations can be linked by dynamic processes within Earth's mantle, through temporal changes in asthenosphere flow beneath the region. The topographic gradient implies westward, pressure‐driven mantle flow beneath the basin, while the rapid spreading rate changes, on order 10 million years, require significant decoupling of regional plate motion from the large‐scale mantle buoyancy distribution through a mechanically weak asthenosphere. Andean topographic growth in late Miocene can explain the most recent South Atlantic spreading velocity reduction, arising from increased plate boundary forcing associated with the newly elevated topography. But this mechanism is unlikely to explain the Late Cretaceous/Tertiary spreading variations, as changes in Andean paleoelevation at the time are small. We propose an unsteady pressure‐driven flow component in the asthenosphere beneath the South Atlantic region to explain the Late Cretaceous/Tertiary spreading rate variations. Temporal changes in mantle flow due to temporal changes in regional mantle pressure gradients imply a correlation of horizontal and vertical motions: we find that this prediction from our models agrees with geologic and geophysical observations of the South Atlantic region, including episodes of passive margin uplift, regional basin reactivation, and magmatic activity.

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Viscous coupling at the lithosphere-asthenosphere boundary

Cited by 83 publications

References 58 publications

The importance of temporal stress variation and dynamic disequilibrium for the initiation of plate tectonics

The importance of temporal stress variation and dynamic disequilibrium for the initiation of plate tectonics

Continental breakup and the dynamics of rifting in back-arc basins: The Gulf of Lion margin

Rapid South Atlantic spreading changes and coeval vertical motion in surrounding continents: Evidence for temporal changes of pressure-driven upper mantle flow

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