Ferreira, A; Faccenda, M; Sturgeon, W; Chang, S-J; Schardong, L; (2019) Ubiquitous lower-mantle anisotropy beneath subduction zones. Nature Geoscience , 12 pp. 301-306. 10.1038/s41561-019-0325-7.

Preview	Text Ferreira_natgeo_AF_final3.pdf - Accepted Version Download (220kB) | Preview
Preview	Text Ferreira_natgeo_AF_figs.pdf - Accepted Version Download (28MB) | Preview

Abstract

Seismic anisotropy provides key information to map the trajectories of mantle flow and understand the evolution of our planet. While the presence of anisotropy in the uppermost mantle is well established, the existence and nature of anisotropy in the transition zone and uppermost lower mantle are still debated. Here we use three-dimensional global seismic tomography images based on a large dataset that is sensitive to this region to show the ubiquitous presence of anisotropy in the lower mantle beneath subduction zones. Whereas above the 660 km seismic discontinuity slabs are associated with fast SV anomalies up to about 3%, in the lower mantle fast SH anomalies of about 2% persist near slabs down to about 1,000–1,200 km. These observations are consistent with 3D numerical models of deformation from subducting slabs and the associated lattice-preferred orientation of bridgmanite produced in the dislocation creep regime in areas subjected to high stresses. This study provides evidence that dislocation creep may be active in the Earth’s lower mantle, providing new constraints on the debated nature of deformation in this key, but inaccessible, component of the deep Earth.

Download activity - last month

Export as XMLJSONCSV

Download activity - last 12 months

Export as JSONCSVXML

Downloads by country - last 12 months

Export as CSVJSONXML

Archive Staff Only

View Item