Three‐dimensional numerical simulations of mantle flow beneath mid‐ocean ridges

Morency, C.; Doin, Marie‐Pierre; Dumoulin, Caroline

doi:10.1029/2004jb003454

Cited by 15 publications

(29 citation statements)

References 47 publications

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“…I restricted my calculations to the domain where the plume material moved laterally faster than the plate rate, 20 km Ma −1 . In addition, movement of the plate relative to the underlying mantle aligns the axes of convection cells of vigorous stagnant‐lid convection in the direction of plate motion [ Morency et al , 2005; Ballmer et al , 2007]. The orientation of relief on the base of the lithosphere as shown in 2‐D in Figure 11 will tend to align in the direction of motion.…”

Section: Three‐dimensional Modelsmentioning

confidence: 99%

Channeling at the base of the lithosphere during the lateral flow of plume material beneath flow line hot spots

Sleep

2008

Geochem Geophys Geosyst

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[1] Chains of volcanic edifices lie along flow lines between plume-fed hot spots and the thin lithosphere at ridge axes. Discovery and Euterpe/Musicians Seamounts are two examples. An attractive hypothesis is that buoyant plume material flows along the base of the lithosphere perpendicular to isochrons. The plume material may conceivably flow in a broad front or flow within channels convectively eroded into the base to the lithosphere. A necessary but not sufficient condition for convective channeling is that the expected stagnant-lid heat flow for the maximum temperature of the plume material is comparable to the half-space surface heat flow of the oceanic lithosphere. Two-dimensional and three-dimensional numerical calculations confirm this inference. A second criterion for significant convective erosion is that it needs to occur before the plume material thins by lateral spreading. Scaling relationships indicate spreading and convection are closely related. Mathematically, the Nusselt number (ratio of convective to conductive heat flow in the plume material) scales with the flux (volume per time per length of flow front) of the plume material. A blob of unconfined plume material thus spreads before the lithosphere thins much and evolves to a slowly spreading and slowly convecting warm region in equilibrium with conduction into the base of the overlying lithosphere. Three-dimensional calculations illustrate this long-lasting (and hence observable) state of plume material away from its plume source. A different flow domain occurs around a stationary hot plume that continuously supplies hot material. The plume convectively erodes the overlying lithosphere, trapping the plume material near its orifice. The region of lithosphere underlain by plume material grows toward the ridge axis and laterally by convective thinning of the lithosphere at its edges. The hottest plume material channels along flow lines. Geologically, the regions of lithosphere underlain by either warm or hot plume material are likely to extend laterally away from the volcanic edifices whether or not channeling occurs.

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Section: Three‐dimensional Modelsmentioning

confidence: 99%

Channeling at the base of the lithosphere during the lateral flow of plume material beneath flow line hot spots

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2008

Geochem Geophys Geosyst

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“…The natural conditions are therefore similar to those in the model of Dumoulin et al (2008). The oceanic lithosphere is older than 16 Ma, and so smallscale convection can initiate in the vicinity of fracture zones (Morency et al, 2005). In our model, we image several lowvelocity anomalies along the Gulf of Aden, from the surface to our maximum investi gation depth (Fig.…”

Section: Transform Fault Zones and Volcanismmentioning

confidence: 78%

“…This means that the condi tions of the lithosphere can promote mantle flow at the edges of continents. Numerical modeling by Morency et al (2005) computed that ~30-40 m.y. after rifting, downward instabilities and then smallscale convection can develop under a cooling oceanic lithosphere.…”

Section: Transform Fault Zones and Volcanismmentioning

confidence: 99%

“…ago (Lucazeau et al, 2008), and therefore no magmatism is expected. Causes of magmatism both during and after continental rifting include small scale convection (e.g., King and Anderson, 1998;Morency et al, 2005) and melt focusing (Kendall et al, 2005), both caused by sharp gradients in the lithosphereasthenosphere boundary topography. In the central and eastern Gulf of Aden postrift magmatism exposed at the surface is localized spatially (Fig.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Upper mantle structure of the southern Arabian margin: Insights from teleseismic tomography

Korostelev¹,

Leroy²,

Keir³

et al. 2015

Geosphere

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We image the lithospheric and upper asthenospheric structure beneath the central and eastern parts of the northern Gulf of Aden rifted passive conti nental margin with 59 broadband stations to evaluate the role of transform fault zones on the evolution of magmapoor continental margins. We used tele seismic tomography to compute a relative P wave velocity model in eastern Yemen and southern Oman down to 400 km depth. Our model shows low velocity anomalies located in the vicinities of five major fracture zones and regions of recent volcanism. These lowvelocity anomalies are likely caused by localized asthenospheric upwelling and partial melting, caused by smallscale convection promoted by gradients in the lithosphereasthenosphere bound ary topography near the fracture zones. In addition, low velocities underlie regions of elevated topography between major sedimentary basins. We sug gest that locally buoyant mantle creates uplift and dynamic topography on the rift margin that affects the course of seasonal rivers and the sedimentation at the mouth of those rivers. Our new P wave velocity model suggests that the dynamic topography and recent volcanism in the central and eastern Gulf of Aden could be due to smallscale convection at the edge of the Arabian plate and/or in the vicinity of fracture zones. GEOSPHERE

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“…The isothermal boundary condition eventually reheats cool material from downwellings thereby causing warm upwellings that interact with the stagnant-lid convection [78]. The vigor of convection wanes as the asthenosphere cools with a no heat flow boundary conditions (or isothermal ones where convection from below is sluggish) [82,83]. One can also generate heat internally within the model from radioactivity.…”

Section: Ambient Basal Temperature Variationsmentioning

confidence: 99%

Small-scale convection beneath oceans and continents

Sleep

2011

Chin. Sci. Bull.

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Small-scale convection supplies heat flow of ~17 mW m 2 to the base of stable continents where xenolith studies resolve the geotherm. However, effects of small-scale convection are difficult to resolve in ocean basins. On first pass, most seafloor appears to subside to an asymptote compatible with ~40 mW m 2 convective heat flow. These common regions are tracked by hotspots so uplift associated with ponded mantle material is an attractive alternative. Unaffected seafloor in the North and South Atlantic continues to subside with the square root of age as expected from pure conduction. The theory of stagnant-lid convection provides good scaling relationships for heat flow. For linear viscosity, heat flow is proportional to the underlying "half-space" viscosity to the 1/3 power and the temperature to change viscosity by a factor of e to the 4/3 power. The formalism is easily modified to represent convection beneath a lid of highly viscous and buoyant cratonal lithosphere and to represent transient convection beneath thickening oceanic lithosphere. Asthenospheric mantle with linear, strongly temperature-dependent, and weakly depth-dependent viscosity is compatible with both oceanic and continental data. More complicated rheology may allow vigorous small-scale convection under most but not all old ocean basins. Still viable hypotheses require poorly understood global features, including lateral variations of asthenospheric temperature. Seismological studies have the potential to resolve the lithosphere-asthenosphere boundary, including local variations of its depth associated with small-scale convection.lithosphere, asthenosphere, ocean depth-age, small-scale convection, craton, mantle plume Citation:Sleep N H. Small-scale convection beneath oceans and continents.

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Three‐dimensional numerical simulations of mantle flow beneath mid‐ocean ridges

Cited by 15 publications

References 47 publications

Channeling at the base of the lithosphere during the lateral flow of plume material beneath flow line hot spots

Channeling at the base of the lithosphere during the lateral flow of plume material beneath flow line hot spots

Upper mantle structure of the southern Arabian margin: Insights from teleseismic tomography

Small-scale convection beneath oceans and continents

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