The nature of subslab slow velocity anomalies beneath South America

Daniel Evan Portner, Susan Beck, George Zandt, Alissa Scire

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Slow seismic velocity anomalies are commonly imaged beneath subducting slabs in tomographic studies, yet a unifying explanation for their distribution has not been agreed upon. In South America two such anomalies have been imaged associated with subduction of the Nazca Ridge in Peru and the Juan Fernández Ridge in Chile. Here we present new seismic images of the subslab slow velocity anomaly beneath Chile, which give a unique view of the nature of such anomalies. Slow seismic velocities within a large hole in the subducted Nazca slab connect with a subslab slow anomaly that appears correlated with the extent of the subducted Juan Fernández Ridge. The hole in the slab may allow the subslab material to rise into the mantle wedge, revealing the positive buoyancy of the slow material. We propose a new model for subslab slow velocity anomalies beneath the Nazca slab related to the entrainment of hot spot material.

Original languageEnglish (US)
Pages (from-to)4747-4755
Number of pages9
JournalGeophysical Research Letters
Volume44
Issue number10
DOIs
StatePublished - May 28 2017

Keywords

  • South America
  • hot spots
  • subduction
  • tomography

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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