The dynamics of off-axis plume-ridge interaction in the uppermost mantle
The dynamics of off-axis plume-ridge interaction in the uppermost mantle
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DOI：
10.1016/0012-821x(95)00201-m
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发表时间：
1996
影响因子：
5.3
通讯作者：
C. Kincaid;J. Schilling;C. Gable
中科院分区：
文献类型：
--
作者：
C. Kincaid;J. Schilling;C. Gable
20年的地球化学和地球物理观测已经形成了地幔柱通道模型，根据该模型，浮力、离轴地幔柱与大洋中脊轴处的分散板块相互作用，这些板块充当上地幔物质的汇。在这里，我们提出的结果，从二维（2-D）的数值实验，将基本的物理和流体动力学方面的地幔柱脊上地幔系统，以测试这个地幔柱脊相互作用模型的可行性。具体而言，实验测试的物理效应，如强大的粘度变化和热和化学浮力迫使在羽脊动力学的相对重要性。结果表明，瞬态和稳态连接之间的离轴羽流和脊的一系列现实的地幔条件。强烈倾斜的流变边界层（RBL）的存在是离轴浮力上升流和扩张脊之间长期连通的必要条件。浮力物质的海岭的流量也被证明是增加与地幔柱密度对比，降低羽流粘度和较小的地幔柱海岭分离距离。羽流脊相互作用制度的基础上，板驱动和浮力驱动流的竞争效应定义。热侵蚀的粘性岩石圈强烈抑制长期的羽脊相互作用，通过提高板块的能力，偏转羽，头部和导管，远离脊轴。
Two decades of geochemical and geophysical observations have led to the plume channel model whereby buoyant, off-axis mantle plumes feed and interact with diverging plates at mid-ocean ridge axes which act as sinks of upper mantle material. Here we present results from two-dimensional (2-D) numerical experiments which incorporate the essential physics and fluid dynamic aspects of the plume-ridge-upper mantle system in order to test the feasibility of this plume-ridge interaction model. Specifically, experiments test the relative importance of physical effects such as strong viscosity variations and thermal and chemical buoyancy forcing in plume-ridge dynamics. Results indicate that both transient and steady-state connections may be established between off-axis plumes and ridges for a range of realistic mantle conditions. The presence of a strongly sloping rheological boundary layer (RBL) is a necessary condition for long-term communication between an off-axis buoyant upwelling and a spreading ridge. The flux of buoyant material to the ridge is also shown to increase with increasing plume-to-mantle density contrast, decreasing plume viscosity and smaller plume-ridge separation distances. Plume-ridge interaction regimes are defined based on the competing effects of plate-driven and buoyancy-driven flow. Thermal erosion of the viscous lithosphere strongly inhibits long-term plume-ridge interaction by enhancing the plates ability to deflect the plume, both head and conduit, away from the ridge axis.