DOI: 10.1016/j.epsl.2020.116570
论文题名: The strength of the Iceland plume: A geodynamical scaling approach
作者: Ribe N.M. ; Tackley P.J. ; Sanan P.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 551 语种: 英语
中文关键词: Iceland
; lubrication theory
; mantle plumes
; plume-ridge interaction
英文关键词: Aspect ratio
; Buoyancy
; Lakes
; Dimensional analysis
; Dynamical model
; Mid Atlantic Ridge
; Numerical solution
; Ridge migration
; Thermomechanical model
; Vertical velocity
; Volumetric rates
; Uncertainty analysis
; buoyancy
; geodynamics
; lithospheric structure
; mantle plume
; thermomechanics
; Atlantic Ocean
; Iceland
; Mid-Atlantic Ridge
英文摘要: An important measure of the strength of a mantle plume is its buoyancy flux B, defined as the integral over a horizontal plane of the product of the vertical velocity and the density deficit within the plume. In the case of the Iceland plume, which currently rises directly beneath the mid-Atlantic ridge, published estimates of B cover a range of a factor of 37. To reconcile these diverse estimates, we study a simple fluid mechanical model of a ridge-centered plume in which plume fluid with spreadability σ (buoyancy over viscosity) is supplied at a volumetric rate Q from a plume conduit located directly beneath a ridge with a half spreading rate U. The plume fluid spreads laterally to form a thin pool beneath a lithosphere whose thickness increases as the square root of age. Application of scaling and dimensional analysis to this model leads to a general scaling law for the ‘waist width’ Ww, the length of the plume-induced elevation anomaly along the ridge. The law has the form Ww/W0=f2(Πb,Πs), where W0=(σQ4/U5)1/6 is the fundamental length scale for plume-ridge interaction, Πb=(σQ/U2)1/3 is of the order of the aspect ratio (width/thickness) of the plume pool, Πs=(κ2σ/U3)1/4 measures the effect on the pool of the sloping base of the lithosphere (κ is the thermal diffusivity), and f2 is an unknown function. We determine f2 using a suite of 32 numerical solutions of a three-dimensional thermomechanical model implemented in the code StagYY (Tackley, 2008). To apply our scaling law to Iceland, we invert it to estimate the buoyancy flux B required to produce a waist width Ww=2300±300 km. After correction for the effect of ridge migration, we find B=2.3±0.6 Mg s−1. This is comparable within uncertainty to the buoyancy flux B=3.0±0.8 Mg s−1 of the Hawaiian plume estimated using a 3-D dynamical model by Ribe and Christensen (1999). © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165233
Appears in Collections: 气候变化与战略
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作者单位: Laboratoire FAST, CNRS, Université Paris-Saclay, Bâtiment 530, Campus Universitaire, Orsay, F-91400, France; Institute of Geophysics, Department of Earth Sciences, ETH Zurich, Sonneggstrasse 5, Zürich, 8092, Switzerland
Recommended Citation:
Ribe N.M.,Tackley P.J.,Sanan P.. The strength of the Iceland plume: A geodynamical scaling approach[J]. Earth and Planetary Science Letters,2020-01-01,551