Thermal transfer between the continental asthenosphere and the oceanic subducting lithosphere: Its effect on subcontinental convection

Rabinowicz, M.; Lago, B.; Froidevaux, C.

doi:10.1029/jb085ib04p01839

Cited by 42 publications

(27 citation statements)

References 41 publications

(1 reference statement)

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“…This is also in agreement with the model proposed by Rabinowicz, Lago & Froidevaux (1980) and Nataf et al (1981) where it is shown that the coldest side of the sinking slab is able to generate a large convection cell under the continent.…”

Section: A and M Souriausupporting

confidence: 91%

Test of tectonic models by great circle Rayleigh waves

Souriau

1983

Geophys J Int

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A large set of published great circle Rayleigh wave phase velocities in the period range 125-350s is used to compare three recent tectonic models (Okal, UvEque, Jordan). Prior to any regionalization, the symmetry property of the great circle integrals is used to obtain a lower limit of the signal/noise ratio in the data. It turns out that the signal is responsible for at least 30 per cent of the data variance in the period range 175-300 s.A standard regression method is applied for computing the 'pure path' velocities and the model efficiency is derived from a variance analysis. It is shown that, even at great depth, none of the three models explains more than 60 per cent of the energy due to the long-wavelength lateral heterogeneities (A 2 6500 km).The three models have nearly the same efficiency for explaining the shortperiod data ( T -125s). Between 200 and 300s, the higher performance of Okal's model indicates that it is important to separate the subduction zones from the other orogenic zones. By perturbing the lateral extension of the subduction zones, it comes out that they constitute on both sides of the subducting slabs wider anomalies than often assumed, suggesting large downgoing flows. On the contrary, the effect of surface features such as marginal seas are restricted to a close region in front of the trenches. Finally, the anomalous ellipticity values deduced directly from great circle data are partly explained by a coupling between tectonics and ellipticity.

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Section: A and M Souriausupporting

confidence: 91%

Test of tectonic models by great circle Rayleigh waves

Souriau

1983

Geophys J Int

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“…In a strongly convecting regime, however, the influence of conducting side walls may be significantly modified by specifying different temperature. Rabinowicz et al [1980] and Nataf et al…”

Section: Discussionmentioning

confidence: 99%

“…The influence of a sharp spatial variation in boundaries on a convective system is a highly nonlinear problem. It has been considered with some specific model geometries, such as for convection due to slab cooling [Rabinowicz et al, 1980;Nataf et al, 1981;Christensen, 1983], and for convection due to cratonic lithosphere or rifting-g&nerated lithospheric necking [e.g., Richter, 1973;Elder, 1976;Keen and Boutilier, 1995;King and Anderson, 1998]. Because these studies focus on specific geological problems, it is difficult to extract the general effects of a heterogeneous top boundary.…”

Section: Introductionmentioning

confidence: 99%

Magmatism and dynamics of continental breakup in the presence of a mantle plume

Korenaga¹

2000

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This thesis studies the dynamics of mantle melting during continental breakups by geophysical, geochemical, and numerical analyses. The first part focuses on the mantle melting and crustal accretion processes during the formation of the Southeast Greenland margin, on the basis of deep-crustal seismic data. A new seismic tomographic method is developed to jointly invert refraction and reflection travel times for a compressional velocity structure, and a long-wavelength structure with strong lateral heterogeneity is successfully recovered, including 30-to 15-km-thick igneous crust within a 150-km-wide continent-ocean transition zone. A nonlinear Monte Carlo analysis is also conducted to establish the absolute uncertainty of model parameters. The derived crustal structure is first used to resolve the origin of a margin gravity high, with new inversion schemes using both seismic and gravity constraints. Density anomalies producing the gravity high seem to be confined within the upper crust, not in the lower crust as suggested for other volcanic margins. A new robust framework is then developed for the petrological interpretation of the velocity structure of igneous crust, and the thick igneous crust formed at the continentocean transition zone is suggested to have resulted from vigorous active upwelling of mantle with only somewhat elevated potential temperature. In the second part, the nature of mantle melting during the formation of the North Atlantic igneous province is studied on the basis of the major element chemistry of erupted lavas. A new fractionation correction scheme based on the Ni concentrations of mantle olivine is used to estimate primary melt compositions, which suggest that this province is characterized by a large degree of major element source heterogeneity. In the third part, the nature of preexisting sublithospheric convection is investigated by a series of finite element analyses, because the strength of such convection is important to define the "normal" state of mantle, the understanding of which is essential to identify any anomalous behavior of mantle such as a mantle plume. The results suggest that small-scale convection is likely in normal asthenosphere, and that the upwelling velocity in such convection is on the order of 1-10 cm/yr. 271 Introductory NotesThis thesis is composed of three parts, all of which are related to the dynamics of mantle melting during continental breakups. In the first part, rifting magmatism associated with the opening of the North Atlantic (at -60 Ma) is investigated on the basis of deep-crustal seismic data collected across the Southeast Greenland continental margin. A new seismic tomographic method is developed to jointly invert refraction and reflection travel times for a two-dimensional velocity structure (Chapter 1). Several key issues in travel time tomography such as velocity-depth ambiguity and absolute parameter uncertainty are identified, and a practical strategy is presented to resolve them. The derived crustal velocity structure is the...

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“…A set of 2-D numerical convective models in the upper mantle in a vertical plane at right angles to the azimuth of the trench, incorporating the cooling action of the sinking slab by a cold vertical wall, shows the formation of a very large convective cell flowing downward along the cold interface of the sinking slab, and next horizontally along the post-spinel interface, before rising again 3000 km away (Fig. 7) (Rabinowicz et al 1980). …”

Section: Geophysical Implicationsmentioning

confidence: 99%

“…A careful modelling of the convective flow driven by the subducting slab acting as a heat sink shows that the convective cells driven by the sinking slab in the upper mantle have a large aspect ratio, at least equal t o 5, and thus have a horizontal extent of at least 3000 km (Rabinowicz, Lago & Froidevaux 1980;Nataf etal. 1981).…”

Section: Introductionmentioning

confidence: 99%

Admittance for a convection in a layered spherical shell

Lago¹,

Rabinowicz²

1984

Geophysical Journal International

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A formalism based on an analytical approximation for convection in a layered spherical shell leads to the computation of the Green kernels for topography and gravity, and to the admittance of gravity over topography for the harmonics of the Earth. We study the role of increasing viscosity with depth, of two layers of convection, and of the coupling with lithospheric plates. It is found that a planet with constant viscosity will have positive values for the admittance for all wavenumbers. However, when a step of viscosity between the lower and upper mantle is assumed, negative values for the first harmonics are achieved. This result explains some long-wave observations and provides evidence for an increase of viscosity in the lower mantle.

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Thermal transfer between the continental asthenosphere and the oceanic subducting lithosphere: Its effect on subcontinental convection

Cited by 42 publications

References 41 publications

Test of tectonic models by great circle Rayleigh waves

Test of tectonic models by great circle Rayleigh waves

Magmatism and dynamics of continental breakup in the presence of a mantle plume

Admittance for a convection in a layered spherical shell

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