Several of Earth's intraplate volcanic provinces are hard to reconcile with the mantle plume hypothesis. Instead, they exhibit characteristics that are more compatible with shallower processes that involve the interplay between uppermost mantle flow and the base of Earth's heterogeneous lithosphere. The mechanisms most commonly invoked are edge-driven convection (EDC) and shear-driven upwelling (SDU), both of which act to focus upwelling flow and the associated decompression melting adjacent to steps in lithospheric thickness. In this study, we undertake a systematic numerical investigation, in both 2-D and 3-D, to quantify the sensitivity of EDC, SDU, and the associated melting to key controlling parameters. Our simulations demonstrate that the spatio-temporal characteristics of EDC are sensitive to the geometry and material properties of the lithospheric step, in addition to the magnitude and depth-dependence of upper-mantle viscosity. These simulations also indicate that asthenospheric shear can either enhance or reduce upwelling velocities and the associated melting, depending upon the magnitude and orientation of flow relative to the lithospheric step. When combined, such sensitivities explain why step changes in lithospheric thickness, which are common along cratonic edges and passive margins, only produce volcanism at isolated points in space and time. Our predicted trends of melt production suggest that, in the absence of potential interactions with mantle plumes, EDC and SDU are viable mechanisms only for Earth's shorter-lived, lower-volume intraplate volcanic provinces.

中文翻译：

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将板内火山活动与岩石圈结构和软流圈流动联系起来

地球的几个板块内火山区很难与地幔柱假说相协调。相反，它们表现出的特征与涉及最上层地幔流与地球异质岩石圈底部之间相互作用的较浅过程更兼容。最常用的机制是边缘驱动对流 (EDC) 和剪切驱动上升流 (SDU)，这两种机制都用于集中上升流和与岩石圈厚度台阶相邻的相关减压熔化。在这项研究中，我们在 2-D 和 3-D 中进行了系统的数值研究，以量化 EDC、SDU 和相关熔化对关键控制参数的敏感性。我们的模拟表明，除了上地幔粘度的大小和深度依赖性之外，EDC 的时空特征还对岩石圈台阶的几何形状和材料特性很敏感。这些模拟还表明，软流圈剪切可以提高或降低上涌速度和相关的熔化，这取决于流动相对于岩石圈台阶的大小和方向。结合起来，这种敏感性解释了为什么岩石圈厚度的阶跃变化（这在克拉通边缘和被动边缘很常见）只在空间和时间的孤立点上产生火山作用。我们预测的熔体产生趋势表明，在没有与地幔柱的潜在相互作用的情况下，EDC 和 SDU 是仅适用于地球寿命较短、