Seismic evidence for orthopyroxene enrichment in the continental lithosphere

Lara S. Wagner, Megan L. Anderson, Jennifer M. Jackson, Susan Beck, George Zandt

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

We assess the ability of predicted seismic velocities (Vp, compressional wave; Vs, shear wave; and Vp/Vs) to identify regions in the upper mantle that are enriched in orthopyroxene relative to normal melt-depleted peridotite compositions. Orthopyroxene enrichment has been found in mantle xenoliths from a number of locations, including the Colorado Plateau and the Kaapvaal craton. We find that the Vp/Vs ratio is very sensitive to orthopyroxene concentration, but it is not sensitive to depletion level. We compare these predicted velocities and Vp/Vs ratios to the high Vs, low Vp/Vs anomaly found above the central Chile-Argentina flat slab. Within error, the predicted velocities of some of the orthopyroxene-enriched xenoliths match the observed velocities from the Chile-Argentina upper mantle. Because the anomaly above the central Chile-Argentina flat slab does not conform to known terrane boundaries but does align with the downgoing Juan Fernandez ridge track, we suggest that the orthopyroxene enrichment in this area may be related to flat slab processes, which would have implications for our understanding of lithospheric silica enrichment in the western U.S. and elsewhere.

Original languageEnglish (US)
Pages (from-to)935-938
Number of pages4
JournalGeology
Volume36
Issue number12
DOIs
StatePublished - 2008

Fingerprint

continental lithosphere
orthopyroxene
slab
upper mantle
anomaly
seismic velocity
peridotite
craton
S-wave
terrane
silica
melt
plateau
mantle

ASJC Scopus subject areas

  • Geology

Cite this

Seismic evidence for orthopyroxene enrichment in the continental lithosphere. / Wagner, Lara S.; Anderson, Megan L.; Jackson, Jennifer M.; Beck, Susan; Zandt, George.

In: Geology, Vol. 36, No. 12, 2008, p. 935-938.

Research output: Contribution to journalArticle

Wagner, Lara S. ; Anderson, Megan L. ; Jackson, Jennifer M. ; Beck, Susan ; Zandt, George. / Seismic evidence for orthopyroxene enrichment in the continental lithosphere. In: Geology. 2008 ; Vol. 36, No. 12. pp. 935-938.
@article{ccb8af79f4ba49faa0c9e81fb2408f76,
title = "Seismic evidence for orthopyroxene enrichment in the continental lithosphere",
abstract = "We assess the ability of predicted seismic velocities (Vp, compressional wave; Vs, shear wave; and Vp/Vs) to identify regions in the upper mantle that are enriched in orthopyroxene relative to normal melt-depleted peridotite compositions. Orthopyroxene enrichment has been found in mantle xenoliths from a number of locations, including the Colorado Plateau and the Kaapvaal craton. We find that the Vp/Vs ratio is very sensitive to orthopyroxene concentration, but it is not sensitive to depletion level. We compare these predicted velocities and Vp/Vs ratios to the high Vs, low Vp/Vs anomaly found above the central Chile-Argentina flat slab. Within error, the predicted velocities of some of the orthopyroxene-enriched xenoliths match the observed velocities from the Chile-Argentina upper mantle. Because the anomaly above the central Chile-Argentina flat slab does not conform to known terrane boundaries but does align with the downgoing Juan Fernandez ridge track, we suggest that the orthopyroxene enrichment in this area may be related to flat slab processes, which would have implications for our understanding of lithospheric silica enrichment in the western U.S. and elsewhere.",
author = "Wagner, {Lara S.} and Anderson, {Megan L.} and Jackson, {Jennifer M.} and Susan Beck and George Zandt",
year = "2008",
doi = "10.1130/G25108A.1",
language = "English (US)",
volume = "36",
pages = "935--938",
journal = "Geology",
issn = "0091-7613",
publisher = "Geological Society of America",
number = "12",

}

TY - JOUR

T1 - Seismic evidence for orthopyroxene enrichment in the continental lithosphere

AU - Wagner, Lara S.

AU - Anderson, Megan L.

AU - Jackson, Jennifer M.

AU - Beck, Susan

AU - Zandt, George

PY - 2008

Y1 - 2008

N2 - We assess the ability of predicted seismic velocities (Vp, compressional wave; Vs, shear wave; and Vp/Vs) to identify regions in the upper mantle that are enriched in orthopyroxene relative to normal melt-depleted peridotite compositions. Orthopyroxene enrichment has been found in mantle xenoliths from a number of locations, including the Colorado Plateau and the Kaapvaal craton. We find that the Vp/Vs ratio is very sensitive to orthopyroxene concentration, but it is not sensitive to depletion level. We compare these predicted velocities and Vp/Vs ratios to the high Vs, low Vp/Vs anomaly found above the central Chile-Argentina flat slab. Within error, the predicted velocities of some of the orthopyroxene-enriched xenoliths match the observed velocities from the Chile-Argentina upper mantle. Because the anomaly above the central Chile-Argentina flat slab does not conform to known terrane boundaries but does align with the downgoing Juan Fernandez ridge track, we suggest that the orthopyroxene enrichment in this area may be related to flat slab processes, which would have implications for our understanding of lithospheric silica enrichment in the western U.S. and elsewhere.

AB - We assess the ability of predicted seismic velocities (Vp, compressional wave; Vs, shear wave; and Vp/Vs) to identify regions in the upper mantle that are enriched in orthopyroxene relative to normal melt-depleted peridotite compositions. Orthopyroxene enrichment has been found in mantle xenoliths from a number of locations, including the Colorado Plateau and the Kaapvaal craton. We find that the Vp/Vs ratio is very sensitive to orthopyroxene concentration, but it is not sensitive to depletion level. We compare these predicted velocities and Vp/Vs ratios to the high Vs, low Vp/Vs anomaly found above the central Chile-Argentina flat slab. Within error, the predicted velocities of some of the orthopyroxene-enriched xenoliths match the observed velocities from the Chile-Argentina upper mantle. Because the anomaly above the central Chile-Argentina flat slab does not conform to known terrane boundaries but does align with the downgoing Juan Fernandez ridge track, we suggest that the orthopyroxene enrichment in this area may be related to flat slab processes, which would have implications for our understanding of lithospheric silica enrichment in the western U.S. and elsewhere.

UR - http://www.scopus.com/inward/record.url?scp=67749148177&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=67749148177&partnerID=8YFLogxK

U2 - 10.1130/G25108A.1

DO - 10.1130/G25108A.1

M3 - Article

AN - SCOPUS:67749148177

VL - 36

SP - 935

EP - 938

JO - Geology

JF - Geology

SN - 0091-7613

IS - 12

ER -