The effect of the large-scale mantle flow field on the Iceland hotspot track
The effect of the large-scale mantle flow field on the Iceland hotspot track
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DOI：
10.1016/j.tecto.2006.12.012
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发表时间：
2008-02-01
期刊：
影响因子：
2.9
通讯作者：
Schmeling, Harro
中科院分区：
文献类型：
--
作者：
Mihalffy, Peter;Steinberger, Bemhard;Schmeling, Harro
为了研究大尺度地幔流场和羽流源深度随时间变化对冰岛羽流结构的影响，进行了流体动力学模拟。在全球模型中计算了地幔中羽流随时间变化的位置和形状，并在上地幔中使用三维笛卡尔模型盒对其进行了细化。基于地震层析成像的密度非均质性计算了全球流。在两个模型中，板块运动历史作为速度边界条件。计算了羽流导管和羽流头的热点轨迹，并与北大西洋的实际水深进行了比较。如果假设在最底地幔中存在地幔柱源，则计算得到的地幔柱导管的表面位置由于下地幔的南向流动而具有南向运动分量。根据层析模型，假定的羽流年龄和浮力向南的分量或多或少占主导地位。在660 km不连续处有一个源的羽流模型只受上地幔和过渡带流动的影响，因此更倾向于向西的热点运动。许多全地幔羽流模型得出的结果是一个v形轨迹，这与格陵兰-冰岛-法罗脊的直线不符。没有强烈的向南运动的模型，例如660 kin深度的羽流源，与实际测深更吻合。从烟羽导管和烟羽头两方面计算了烟羽轨迹。在距平温度为120 K时，羽头轨迹与测深吻合最好。(C) 2007 Elsevier B.V.版权所有
Fluid dynamical simulations were carried out in order to investigate the effect of the large-scale mantle flow field and the depth of the plume source on the structure of the Iceland plume through time. The time-dependent location and shape of the plume in the Earth's mantle was calculated in a global model and it was refined in the upper mantle using a 3D Cartesian model box. Global flow was computed based on density heterogeneities derived from seismic tomography. Plate motion history served as a velocity boundary condition in both models. Hotspot tracks of the plume conduits and the plume head were calculated and compared to actual bathymetry of the North Atlantic. If a plume source in the lowermost mantle is assumed, the calculated surface position of the plume conduit has a southward component of motion due to southward flow in the lower mantle. Depending on tomography model, assumed plume age and buoyancy the southward component is more or less dominating. Plume models having a source at the 660 km discontinuity are only influenced by flow in the upper mantle and transition zone and hence rather yield westward hotspot motion. Many whole-mantle plume models result in a V-shaped track, which does not match the straight Greenland-Iceland-Faroe ridge. Models without strong southward motion, such as for a plume source at 660 kin depth, match actual bathymetry better. Plume tracks were calculated from both plume conduits and plume heads. A plume head of 120 K anomalous temperature gives the best match between plume head track and bathymetry. (C) 2007 Elsevier B.V. All rights reserved.