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Abstract Subduction zones are fundamental features of Earth's mantle convection and plate tectonics, but mantle flow and pressure around slabs are poorly understood because of the lack of direct observational constraints on subsurface flow. To characterize the linkages between slabs and mantle flow, we integrate high‐resolution representations of Earth's lithosphere and slabs into a suite of global mantle convection models to produce physically plausible present‐day flow fields for Earth's mantle. We find that subduction zones containing wide, thick, and long slabs dominate regional mantle flow in the neighboring regions and this flow conforms to patterns predicted by simpler regional subduction models. These subduction zones, such as Kuril‐Japan‐Izu‐Bonin‐Mariana, feature prismatic poloidal flow coupled to the downgoing slab that rotates toward toroidal slab‐parallel flow near the slab edge. However, other subduction zones, such as Sumatra, deviate from this pattern because of the competing influence of other slabs or longer‐wavelength mantle flow, showing that upper mantle flow can link separate subduction zones and how flow at subduction zones is influenced by broader scale mantle flow. We find that the non‐linear dislocation creep reduces the coupling between slab motion and asthenospheric flow and increases the occurrence of non‐ideal flow, in line with inferences derived from seismological constraints on mantle anisotropy.
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The Topographic Signature of Mantle Pressure Build‐Up Beneath Subducting Plates: Insights From Spherical Subduction Models
Abstract Subduction zones are associated with spatially heterogeneous pressure fields that, depending on location, push/pull on Earth's surface producing dynamic topography (DT). Despite this, subduction zones, and associated pressure fields, are typically over‐simplified within global mantle flow models. Here, I use subduction models within a global domain to probe mantle pressure build‐up beneath subducting plates (SPs) and the resulting DT. Positive pressure develops beneath the SP in most subduction models. This produces positive DT (≤450 m) and tilts the SP upwards toward the trench (≤0.25 m/km). As SP size increases, the pressure magnitude increases producing greater topography/tilting. At a global scale, I find potential evidence for the modeled tilting in published residual topography. I argue that the rigorous incorporation of subduction zones into mantle flow models, and hence the inclusion of this signal, is needed to continue to bring future DT predictions and observational estimates into closer alignment.
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- Award ID(s):
- 2147997
- PAR ID:
- 10385589
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 49
- Issue:
- 22
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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