Differential Rotation Between Lithosphere and Mantle' A Consequence of Lateral Mantle Viscosity Variations
Differential Rotation Between Lithosphere and Mantle' A Consequence of Lateral Mantle Viscosity Variations
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DOI：
10.1029/91jb00204
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发表时间：
1991-05
影响因子：
--
通讯作者：
Y. Ricard;C. Doglioni;R. Sabadini
中科院分区：
文献类型：
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作者：
Y. Ricard;C. Doglioni;R. Sabadini
在所谓的热点参考系中对板块运动的描述引入了岩石圈相对于地幔的全球旋转。这种自转被称为1阶环向场，大致是向西的。它的幅度约为2厘米/年，并在不同世代的板块构造模型中得到一致的发现。不同的作者试图将这种观测与地球自转减速、极地漂移或潮汐阻力联系起来。然而，这些不同的物理机制不能解释所要求的幅度。在本文中，我们使用不同的相对板块运动模型来比较这一旋转向量值，该模型以热点坐标系表示。在具有横向粘性变化的模型地球中，预测了差动自转。观测到的岩石圈净自转与模型地球的动力学一致，在该模型中，海洋下的软流层粘度至少比大陆下的低一个数量级。岩石圈的这种相对向西的漂移可能解释了东西倾斜俯冲带之间的显著构造差异。
The description of plate motions in the so-called hotspot reference frame introduces a global rotation of the lithosphere with respect to the mantle. This rotation, called toroidal field of degree 1, is roughly westward. It reaches an amplitude of about 2 cm/yr and has been consistently found in the different generation of plate tectonic models. Various authors have tried to relate this observation to the deceleration of the Earth's rotation, to polar wander, or to tidal drag. However, these different physical mechanisms cannot explain the requested amplitude. In this paper, we compare the values of this rotation vector using different relative plate motion models expressed in the hotspot reference frame. In a model Earth with lateral viscosity variations, a differential rotation is predicted. The observed net lithospheric rotation is consistent with the dynamics of a model Earth where the asthenospheric viscosity below the oceans is at least one order of magnitude lower than underneath the continents. This relative westward drift of the lithosphere may account for the significant structural differences between east or west dipping subduction zones.