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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Plumes in a convecting mantle: Models and observations for individual hotspots [Review]
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Plumes in a convecting mantle: Models and observations for individual hotspots [Review]

机译：对流幔柱中的羽状物：单个热点的模型和观测[评论]

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The motion of hotspots and the deformation of their underlying plume conduits as calculated within models of global mantle flow are presented. A new list of 44 possible hotspots with associated tracks has been compiled. For all of them, calculations have been performed under consideration of individual age and anomalous mass Aux for three different models of plume buoyancy and mantle flow. Plume source depth has usually been assumed to be the top of D", but an alternative source depth at the 670-km discontinuity has also been considered. Using models of relative plate motions and boundaries, hotspot tracks on plates have been calculated and compared with age data, ocean floor topography, and distribution of volcanics on continents. Absolute plate motions have been redetermined under consideration of hotspot motion, using a new least squares method. For the Hawaiian and Yellowstone hotspots, source locations and hotspot motion have been computed for a total of up to 23 different models. The results show plume conduits being tilted, with source regions at the D" moving in the lowermost mantle flow, generally toward large-scale upwellings under southern Africa and the south central Pacific. Hotspot surface motion often represents the horizontal component of midmantle flow; which is frequently opposite to plate motion, toward ridges and away from subduction zones. In particular, almost all models tested predict southward motion of the Hawaii and Kerguelen hotspots and westward motion of the Iceland hotspot. For models including hotspot motion the agreement between calculated and observed hotspot tracks is frequently about as good as, or better than, for the fixed hotspot model, but sometimes fixed hotspots give the best fit. In some: cases where the track ends at a subduction zone, e.g., for the Bowie hotspot, results can give indications about the otherwise unknown age of the hotspot. In other cases, especially for the Tahiti hotspot, results suggest an origin shallower than D", and in yet other cases, particularly East Africa, the failure of the hotspot models used supports other evidence indicating the presence of comparatively broad upwellings rather than localized plumes. [References: 103]
机译：提出了在全球地幔流动模型中计算出的热点运动及其下伏羽流导管的变形。已编辑了44个可能的热点以及相关轨道的新列表。对于所有这些，已经在考虑个体年龄和异常质量辅助的情况下对三种不同的羽浮力和地幔流模型进行了计算。通常以羽状源深度为D“的顶部，但也考虑了670 km不连续处的替代性源深度。使用相对板块运动和边界模型，计算了板块上的热点轨迹并将其与年龄数据，海床地形和大陆上的火山分布。考虑到热点运动，使用新的最小二乘法重新确定了绝对板块运动;对于夏威夷和黄石热点，已经计算了总共多达23种不同的模型。结果显示，羽流导管倾斜，D“处的源区在最低的地幔流中移动，通常流向南部非洲和南部中太平洋下方的大规模上升流。热点表面运动通常代表着中地幔流动的水平分量。它通常与板块运动相反，朝向板脊并远离俯冲带。特别是，几乎所有测试的模型都可以预测夏威夷和克格伦热点的向南运动以及冰岛热点的向西运动。对于包括热点运动的模型，计算出的热点轨迹和观察到的热点轨迹之间的一致性通常与固定热点模型差不多好，或好于固定热点模型，但有时固定热点会提供最佳拟合。在某些情况下，例如在Bowie热点的轨道在俯冲带结束的情况下，结果可以表明该热点年龄的未知情况。在其他情况下，特别是对于塔希提岛热点，结果表明其起源比D“浅，在其他情况下，尤其是在东非，所使用的热点模型的失败也支持了其他证据，表明存在相对较宽的上升流而不是局部羽状流。 [参考：103]

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