Heterogeneous upper mantle structure beneath the Ross Sea Embayment and Marie Byrd Land, West Antarctica, revealed by P-wave tomography

Austin L. White-Gaynor, Andrew Arnold Nyblade, Richard C. Aster, Douglas A. Wiens, Peter D. Bromirski, Peter Gerstoft, Ralph A. Stephen, Samantha E. Hansen, Terry Wilson, Ian W. Dalziel, Audrey D. Huerta, J. Paul Winberry, Sridhar Anandakrishnan

Research output: Contribution to journalArticle

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Abstract

We present an upper mantle P-wave velocity model for the Ross Sea Embayment (RSE) region of West Antarctica, constructed by inverting relative P-wave travel-times from 1881 teleseismic earthquakes recorded by two temporary broadband seismograph deployments on the Ross Ice Shelf, as well as by regional ice- and rock-sited seismic stations surrounding the RSE. Faster upper mantle P-wave velocities (∼+1%) characterize the eastern part of the RSE, indicating that the lithosphere in this part of the RSE may not have been reheated by mid-to-late Cenozoic rifting that affected other parts of the Late Cretaceous West Antarctic Rift System. Slower upper mantle velocities (∼−1%) characterize the western part of the RSE over a ∼500 km-wide region, extending from the central RSE to the Transantarctic Mountains (TAM). Within this region, the model shows two areas of even slower velocities (∼−1.5%) centered beneath Mt. Erebus and Mt. Melbourne along the TAM front. We attribute the broader region of slow velocities mainly to reheating of the lithospheric mantle by Paleogene rifting, while the slower velocities beneath the areas of recent volcanism may reflect a Neogene-present phase of rifting and/or plume activity associated with the formation of the Terror Rift. Beneath the Ford Ranges and King Edward VII Peninsula in western Marie Byrd Land, the P-wave model shows lateral variability in upper mantle velocities of ±0.5% over distances of a few hundred km. The heterogeneity in upper mantle velocities imaged beneath the RSE and western Marie Byrd Land, assuming no significant variation in mantle composition, indicates variations in upper mantle temperatures of at least 100 °C. These temperature variations could lead to differences in surface heat flow of ∼±10 mW/m 2 and mantle viscosity of 10 2 Pa s regionally across the study area, possibly influencing the stability of the West Antarctic Ice Sheet by affecting basal ice conditions and glacial isostatic adjustment.

Original languageEnglish (US)
Pages (from-to)40-50
Number of pages11
JournalEarth and Planetary Science Letters
Volume513
DOIs
StatePublished - May 1 2019

Fingerprint

mantle structure
Antarctic regions
P waves
tomography
P-wave
Tomography
upper mantle
Earth mantle
Ice
rifting
mantle
ice
wave velocity
mountains
basal ice
Ross ice shelf
Seismographs
mountain
ice shelf
seismograph

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

White-Gaynor, Austin L. ; Nyblade, Andrew Arnold ; Aster, Richard C. ; Wiens, Douglas A. ; Bromirski, Peter D. ; Gerstoft, Peter ; Stephen, Ralph A. ; Hansen, Samantha E. ; Wilson, Terry ; Dalziel, Ian W. ; Huerta, Audrey D. ; Paul Winberry, J. ; Anandakrishnan, Sridhar. / Heterogeneous upper mantle structure beneath the Ross Sea Embayment and Marie Byrd Land, West Antarctica, revealed by P-wave tomography. In: Earth and Planetary Science Letters. 2019 ; Vol. 513. pp. 40-50.
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abstract = "We present an upper mantle P-wave velocity model for the Ross Sea Embayment (RSE) region of West Antarctica, constructed by inverting relative P-wave travel-times from 1881 teleseismic earthquakes recorded by two temporary broadband seismograph deployments on the Ross Ice Shelf, as well as by regional ice- and rock-sited seismic stations surrounding the RSE. Faster upper mantle P-wave velocities (∼+1{\%}) characterize the eastern part of the RSE, indicating that the lithosphere in this part of the RSE may not have been reheated by mid-to-late Cenozoic rifting that affected other parts of the Late Cretaceous West Antarctic Rift System. Slower upper mantle velocities (∼−1{\%}) characterize the western part of the RSE over a ∼500 km-wide region, extending from the central RSE to the Transantarctic Mountains (TAM). Within this region, the model shows two areas of even slower velocities (∼−1.5{\%}) centered beneath Mt. Erebus and Mt. Melbourne along the TAM front. We attribute the broader region of slow velocities mainly to reheating of the lithospheric mantle by Paleogene rifting, while the slower velocities beneath the areas of recent volcanism may reflect a Neogene-present phase of rifting and/or plume activity associated with the formation of the Terror Rift. Beneath the Ford Ranges and King Edward VII Peninsula in western Marie Byrd Land, the P-wave model shows lateral variability in upper mantle velocities of ±0.5{\%} over distances of a few hundred km. The heterogeneity in upper mantle velocities imaged beneath the RSE and western Marie Byrd Land, assuming no significant variation in mantle composition, indicates variations in upper mantle temperatures of at least 100 °C. These temperature variations could lead to differences in surface heat flow of ∼±10 mW/m 2 and mantle viscosity of 10 2 Pa s regionally across the study area, possibly influencing the stability of the West Antarctic Ice Sheet by affecting basal ice conditions and glacial isostatic adjustment.",
author = "White-Gaynor, {Austin L.} and Nyblade, {Andrew Arnold} and Aster, {Richard C.} and Wiens, {Douglas A.} and Bromirski, {Peter D.} and Peter Gerstoft and Stephen, {Ralph A.} and Hansen, {Samantha E.} and Terry Wilson and Dalziel, {Ian W.} and Huerta, {Audrey D.} and {Paul Winberry}, J. and Sridhar Anandakrishnan",
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White-Gaynor, AL, Nyblade, AA, Aster, RC, Wiens, DA, Bromirski, PD, Gerstoft, P, Stephen, RA, Hansen, SE, Wilson, T, Dalziel, IW, Huerta, AD, Paul Winberry, J & Anandakrishnan, S 2019, 'Heterogeneous upper mantle structure beneath the Ross Sea Embayment and Marie Byrd Land, West Antarctica, revealed by P-wave tomography', Earth and Planetary Science Letters, vol. 513, pp. 40-50. https://doi.org/10.1016/j.epsl.2019.02.013

Heterogeneous upper mantle structure beneath the Ross Sea Embayment and Marie Byrd Land, West Antarctica, revealed by P-wave tomography. / White-Gaynor, Austin L.; Nyblade, Andrew Arnold; Aster, Richard C.; Wiens, Douglas A.; Bromirski, Peter D.; Gerstoft, Peter; Stephen, Ralph A.; Hansen, Samantha E.; Wilson, Terry; Dalziel, Ian W.; Huerta, Audrey D.; Paul Winberry, J.; Anandakrishnan, Sridhar.

In: Earth and Planetary Science Letters, Vol. 513, 01.05.2019, p. 40-50.

Research output: Contribution to journalArticle

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T1 - Heterogeneous upper mantle structure beneath the Ross Sea Embayment and Marie Byrd Land, West Antarctica, revealed by P-wave tomography

AU - White-Gaynor, Austin L.

AU - Nyblade, Andrew Arnold

AU - Aster, Richard C.

AU - Wiens, Douglas A.

AU - Bromirski, Peter D.

AU - Gerstoft, Peter

AU - Stephen, Ralph A.

AU - Hansen, Samantha E.

AU - Wilson, Terry

AU - Dalziel, Ian W.

AU - Huerta, Audrey D.

AU - Paul Winberry, J.

AU - Anandakrishnan, Sridhar

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N2 - We present an upper mantle P-wave velocity model for the Ross Sea Embayment (RSE) region of West Antarctica, constructed by inverting relative P-wave travel-times from 1881 teleseismic earthquakes recorded by two temporary broadband seismograph deployments on the Ross Ice Shelf, as well as by regional ice- and rock-sited seismic stations surrounding the RSE. Faster upper mantle P-wave velocities (∼+1%) characterize the eastern part of the RSE, indicating that the lithosphere in this part of the RSE may not have been reheated by mid-to-late Cenozoic rifting that affected other parts of the Late Cretaceous West Antarctic Rift System. Slower upper mantle velocities (∼−1%) characterize the western part of the RSE over a ∼500 km-wide region, extending from the central RSE to the Transantarctic Mountains (TAM). Within this region, the model shows two areas of even slower velocities (∼−1.5%) centered beneath Mt. Erebus and Mt. Melbourne along the TAM front. We attribute the broader region of slow velocities mainly to reheating of the lithospheric mantle by Paleogene rifting, while the slower velocities beneath the areas of recent volcanism may reflect a Neogene-present phase of rifting and/or plume activity associated with the formation of the Terror Rift. Beneath the Ford Ranges and King Edward VII Peninsula in western Marie Byrd Land, the P-wave model shows lateral variability in upper mantle velocities of ±0.5% over distances of a few hundred km. The heterogeneity in upper mantle velocities imaged beneath the RSE and western Marie Byrd Land, assuming no significant variation in mantle composition, indicates variations in upper mantle temperatures of at least 100 °C. These temperature variations could lead to differences in surface heat flow of ∼±10 mW/m 2 and mantle viscosity of 10 2 Pa s regionally across the study area, possibly influencing the stability of the West Antarctic Ice Sheet by affecting basal ice conditions and glacial isostatic adjustment.

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