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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >The strength of the Iceland plume: Ageodynamical scaling approach
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The strength of the Iceland plume: Ageodynamical scaling approach

机译：冰岛羽流的力量：逐步缩放方法

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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 Bcover 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 sigma(buoyancy over viscosity) is supplied at a volumetric rate Qfrom 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' W-w, the length of the plume-induced elevation anomaly along the ridge. The law has the form W-w/W-0= f(2)(Pi(b), Pi(s)), where W-0=(sigma Q(4)/U-5)(1/6) is the fundamental length scale for plume-ridge interaction, Pi(b)=(sigma Q/ U-2)1/3is of the order of the aspect ratio (width/thickness) of the plume pool, Pi(s)=(kappa(2)sigma/U-3)(1/4) measures the effect on the pool of the sloping base of the lithosphere (kappa is the thermal diffusivity), and f(2) is an unknown function. We determine f(2) 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 Brequired to produce a waist width W-w= 2300 +/- 300km. 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). (C) 2020 Elsevier B.V. All rights reserved.
机译：披风羽流的强度的重要衡量标准是其浮力磁通B，定义为垂直速度的乘积水平平面的积分以及羽流内的密度缺陷。在冰岛羽流的情况下，目前直接在大西洋脊下升起，BCOVER的估计为37倍的范围。为了调和这些多样化估计，我们研究了一个简单的脊柱羽流的流体机械模型其中具有可铺展σ的羽流（浮力过度粘度）以体积速率QFRom在直接位于脊下位于具有半扩散速率U的脊柱的羽流速率Q.横向延伸以形成厚度增加的岩石圈下方的薄池。作为年龄的平方根。将缩放和尺寸分析在该模型中的应用导致了“腰宽”W-W的一般缩放法，沿着脊的羽流诱导的升高异常的长度。法律具有WW / W-0 = F（2）（PI（B），PI）的形式，其中W-0 =（Sigma Q（4）/ U-5）（1/6）是羽毛 - 脊相互作用的基本长度，pi（b）=（sigma q / u-2）1/3是羽流池的纵横比（宽度/厚度）的顺序，pi（s）=（kappa（ 2）Sigma / U-3）（1/4）测量对岩石圈的倾斜底座池的影响（κ是热扩散率），F（2）是未知功能。我们使用在代码STAGYY（Tackley，2008）中实施的三维热机械模型的32个数值解的套件来确定F（2）。要将扩展法应用于冰岛，我们将其倒置以估计充满安全的浮力，以产生腰部宽度W-W = 2300 +/- 300km。校正脊迁移效果后，发现B = 2.3 +/- 0.6 mg s（-1）。这在使用Ribe和Christensen（1999）的3-D动态模型的夏威夷羽流的浮动助焊剂B = 3.0 +/- 0.8mg S（-1）的不确定度内相当。 （c）2020 Elsevier B.v.保留所有权利。

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