Toroidal mantle flow through the western U.S. slab window

George Zandt, E. Humphreys

Research output: Contribution to journalArticle

117 Citations (Scopus)

Abstract

The circular pattern of anisotropic fast-axis orientations of split SKS arrivals observed in the western U.S. cannot be attributed reasonably to either preexisting lithospheric fabric or to asthenospheric strain related to global-scale plate motion. A plume origin for this pattern accounts more successfully for the anisotropy field, but little evidence exists for an active plume beneath central Nevada. We suggest that mantle flow around the edge of the sinking Gorda-Juan de Fuca slab is responsible for creating the observed anisotropy. Seismic images and kinematic reconstructions of Gorda-Juan de Fuca plate subduction have the southern edge of this plate extending from the Mendocino triple junction to beneath central Nevada, and flow models of narrow subducted slabs produce a strong toroidal flow field around the edge of the slab, consistent with the observed pattern of anisotropy. This flow may enhance uplift, extension, and magmatism of the northern Basin and Range while inhibiting extension of the southern Basin and Range.

Original languageEnglish (US)
Pages (from-to)295-298
Number of pages4
JournalGeology
Volume36
Issue number4
DOIs
StatePublished - Apr 2008

Fingerprint

slab
anisotropy
mantle
plume
Juan de Fuca plate
triple junction
plate motion
basin
flow field
magmatism
subduction
kinematics
uplift
fabric

Keywords

  • Basin and range
  • Gorda-Juan de Fuca slab
  • Mantle anisotropy
  • Mantle flow

ASJC Scopus subject areas

  • Geology

Cite this

Toroidal mantle flow through the western U.S. slab window. / Zandt, George; Humphreys, E.

In: Geology, Vol. 36, No. 4, 04.2008, p. 295-298.

Research output: Contribution to journalArticle

Zandt, George ; Humphreys, E. / Toroidal mantle flow through the western U.S. slab window. In: Geology. 2008 ; Vol. 36, No. 4. pp. 295-298.
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