THE DYNAMICS OF PLUME-RIDGE INTERACTION, 1: RIDGE-CENTERED PLUMES
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dc.contributor.author | Ribe N.M. | |
dc.contributor.author | Christensen U.R. | |
dc.contributor.author | Theiszing J. | |
dc.date.accessioned | 2020-11-25T05:23:37Z | |
dc.date.available | 2020-11-25T05:23:37Z | |
dc.date.issued | 1995 | |
dc.identifier | https://elibrary.ru/item.asp?id=658707 | |
dc.identifier.citation | Earth and Planetary Science Letters, 1995, , 1, 155-168 | |
dc.identifier.issn | 0012-821X | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/19489 | |
dc.description.abstract | We investigate the dynamics of mantle plumes rising beneath mid-ocean ridges. To clarify the physics of this process, we examine first a simple 'lubrication theory' model in which a point source (analogous to a plume 'stem') of volume flux Q located directly beneath the ridge releases buoyant fluid into a viscous corner flow driven by a velocity boundary conditionu (x) = U tanh(xd), where U is the half-spreading rate and the 'gap width' between the diverging plates is # 5d. Numerical solutions of the differential equation governing the plume head thickness S(x,y) show how the width W of the plume head along the ridge depends on Q,U,d, and σ = gΔρ, where Δρ is the density deficit of the plume and η is the viscosity. In the geophysically relevant 'narrow gap' limit (Q)1 # d, W # (QU)1Π0.053b, where Πb = QσU2 is the 'buoyancy number'. Numerical solutions of a more realistic 3D convection model with strongly temperature and pressure-dependent viscosity obey a nearly identical scaling law, and show no evidence that W is increased by 'upslope' flow of plume material toward the ridge along the sloping base of the rheological lithosphere. To apply our model to Iceland, we incorporate into it a melting parameterization that allows prediction of the excess crustal thickness produced by melting in the plume head. This extended model shows that the observed depth anomalies along the Mid-Atlantic Ridge near Iceland cannot be explained by a hot (temperature contrast ΔT # 250°C) and narrow (radius # 60 km) ridge-centered plume. Instead, the anomalies are consistent with a much cooler and broader upwelling. | |
dc.title | THE DYNAMICS OF PLUME-RIDGE INTERACTION, 1: RIDGE-CENTERED PLUMES | |
dc.type | Статья |
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