Upper mantle anisotropy beneath Peru from SKS splitting: Constraints on flat slab dynamics and interaction with the Nazca Ridge
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Response of the mantle to flat slab evolution: Insights from local S splitting beneath Peru
The dynamics of flat subduction, particularly the interaction between a flat slab and the overriding plate, are poorly understood. Here we study the (seismically) anisotropic properties and deformational regime of the mantle directly above the Peruvian flat slab. We analyze shear wave splitting from 370 local S events at 49 stations across southern Peru. We find that the mantle above the flat s...
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[1] Flat or shallow subduction is a relatively widespread global occurrence, but the dynamics remain poorly understood. In particular, the interaction between flat slabs and the surrounding mantle flow has yet to be studied in detail. Here we present measurements of seismic anisotropy to investigate mantle flow beneath the Peruvian flat-slab segment, the largest present-day region of flat subdu...
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The effects of complex slab geometries on the surrounding mantle flow field are still poorly understood. Here we combine shear wave velocity structure with Rayleigh wave phase anisotropy to examine these effects in southern Peru, where the slab changes its geometry from steep to flat. To the south, where the slab subducts steeply, we find trench-parallel anisotropy beneath the active volcanic a...
متن کاملInternal deformation of the subducted Nazca slab inferred from seismic anisotropy
Withinoceanic lithospherea fossilized fabric is oftenpreserved originating from the time of plate formation. Such fabric is thought to form at the mid-ocean ridge when olivine crystals align with the direction of plate spreading1,2. It is unclear, however, whether this fossil fabric is preserved within slabs during subduction or overprinted by subduction-induced deformation. The alignment of ol...
متن کاملLowermost mantle anisotropy beneath the northwestern Pacific: Evidence from PcS, ScS, SKS, and SKKS phases
[1] In this study, we utilize data from broadband seismic stations of the Japanese F-net network to investigate anisotropic structure in the lowermost mantle beneath the northwestern Pacific. The comparison of shear wave splitting from phases that have similar paths in the upper mantle but different paths in the lowermost mantle, such as PcS/ScS or SKS/SKKS, can yield constraints on anisotropy ...
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تاریخ انتشار 2015