We investigate the relationship between the global distribution of deep slab dips (at 250‐ to 300‐km depth) and pressure and circulation in the upper mantle. Using an analytic method to compute dynamic pressure in a 3‐D global upper mantle domain, and a force balance between slab dip, slab buoyancy, and pressure, we model dips for all major subduction zones. Overall, our models suggest that global‐scale mantle flow, as dictated by the shapes and velocities of Earth's plates and slabs, plays a fundamental role in creating the global pattern of slab dips. The dip trends of the South American and western Pacific subduction zones are controlled, in our models, by spatial variations in the dynamic pressure associated with flow. Our best fitting models produce global root mean square dip misfits of less than 10° for asthenospheric viscosities of 2.5–4.0 × 10²⁰ Pas. This result is only obtained with a large flux of asthenosphere from upper to lower mantle at subduction boundaries, occurring on the overriding plate side of slabs, without which dips are significantly steeper than observed. This effect cannot be resolved by processes that affect only certain subduction systems and requires flux of asthenosphere into the lower mantle at subduction systems globally (or an alternative mechanism that produces more negative pressures on the overriding plate side of slabs). Upper mantle pressure fields that fit global slab dips yield negative dynamic pressure on the upper plate side of slabs, positive pressure on the subducting plate side, and an east‐to‐west pressure increase beneath the Pacific Plate.

中文翻译：

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俯冲动力学和地幔压力：2.全面了解板倾角和上地幔环流

我们研究了深平板倾角（在250至300 km深度）的全球分布与上地幔压力和环流之间的关系。我们使用一种解析方法来计算3D全球上地幔区域中的动压力，并在平板倾角，平板浮力和压力之间进行力平衡，从而对所有主要俯冲带的倾角进行建模。总体而言，我们的模型表明，由地球板块和平板的形状和速度所决定的全球范围的地幔流动在创建平板倾角的全球格局中起着根本性的作用。在我们的模型中，南美和西太平洋俯冲带的倾角趋势是通过与流量相关的动压的空间变化来控制的。我们的最佳拟合模型对于2的软流层黏度产生小于10°的整体均方根倾角失配。²⁰ 帕斯。仅在俯冲边界上从上地幔到下地幔的软流圈通量大的情况下才能获得该结果，该俯冲边界发生在平板的上覆板侧，没有俯冲比观察到的陡峭。这种影响不能通过仅影响某些俯冲系统的过程来解决，并且该过程需要全球范围内的俯冲系统将软流圈通入下地幔（或在板的上覆板侧产生更大负压的替代机制）。适应整体平板倾角的上地幔压力场在平板的上板侧产生负动压，在俯冲板侧产生正压，在太平洋板块下方产生东西向的压力增加。