Origin of lateral heterogeneities in the upper mantle beneath southeast Australia from seismic tomography

N Rawlinson, B L N Kennett, M Salmon, R. A. Glen

Research output: Chapter in Book/Report/Conference proceedingChapter (peer-reviewed)

9 Citations (Scopus)

Abstract

We use teleseismic body wave tomography to reveal anomalous P wave velocity variations in the upper mantle beneath south-east Australia. Data are sourced from the WOMBAT transportable seismic array, the largest of its kind in the southern hemisphere, which enables horizontal resolution of approximately 50 km to be achieved over a large region that includes Victoria, New South Wales and southern South Australia. In order to account for long-wavelength structure that is lost due to the use of multiple teleseismic datasets from adjacent arrays with non-overlapping recording periods, the AuSREM mantle model is included as prior information in the inversion. Furthermore, AuSREM crust and Moho structure is explicitly included in the initial model in order to account for the presence of shallow heterogeneity which is poorly constrained by the teleseismic dataset. The P wave velocity model obtained from the joint inversion of WOMBAT teleseismic data represents a vast new resource on the seismic structure of the upper mantle beneath south-east Australia. One of the most striking features of the model is the presence of a north-dipping low-velocity anomaly beneath the Newer Volcanics province, a Quaternary intraplate basaltic province in western Victoria. The anomaly appears to terminate at approximately 200 km depth and has a structure that is more suggestive of a source confined to the upper mantle rather than a deeply rooted mantle plume. Other features that can be observed include a high-velocity anomaly beneath the Curnamona province and a high-velocity salient beneath the New England Orogen . Of particular interest is an extensive high-velocity anomaly beneath the Lachlan Orogen, which coincides almost exactly with the surface expression of the Hay–Booligal Zone in the south, and extends northwards beneath the Macquarie Arc. The higher velocities beneath the Hay–Booligal Zone are consistent with the idea that it may be floored by a fragment of Proterozoic continental lithosphere that was once part of the east Gondwana margin, while the higher velocities beneath the Macquarie Arc may be related to its origin as an intra-oceanic arc.
Original languageEnglish
Title of host publicationThe Earth's Heterogeneous Mantle
Subtitle of host publicationA Geophysical, Geodynamical, and Geochemical Perspective
EditorsAmir Khan, Frederic Deschamps
PublisherSpringer
Pages47-78
Number of pages32
ISBN (Electronic)978-3-319-15627-9
ISBN (Print)9783319156262
DOIs
Publication statusPublished - 2015

Publication series

NameSpringer Geosphysics
PublisherSpringer

Fingerprint

seismic tomography
upper mantle
anomaly
P-wave
wave velocity
teleseismic wave
continental lithosphere
body wave
mantle plume
Moho
Gondwana
tomography
Southern Hemisphere
Proterozoic
crust
mantle
wavelength
resource
province

Keywords

  • Australia
  • continental lithosphere
  • seismic tomography
  • accretionary orogen
  • Gondwana

Cite this

Rawlinson, N., Kennett, B. L. N., Salmon, M., & Glen, R. A. (2015). Origin of lateral heterogeneities in the upper mantle beneath southeast Australia from seismic tomography. In A. Khan, & F. Deschamps (Eds.), The Earth's Heterogeneous Mantle: A Geophysical, Geodynamical, and Geochemical Perspective (pp. 47-78). (Springer Geosphysics). Springer . https://doi.org/10.1007/978-3-319-15627-9_2

Origin of lateral heterogeneities in the upper mantle beneath southeast Australia from seismic tomography. / Rawlinson, N; Kennett, B L N; Salmon, M; Glen, R. A.

The Earth's Heterogeneous Mantle: A Geophysical, Geodynamical, and Geochemical Perspective. ed. / Amir Khan; Frederic Deschamps. Springer , 2015. p. 47-78 (Springer Geosphysics).

Research output: Chapter in Book/Report/Conference proceedingChapter (peer-reviewed)

Rawlinson, N, Kennett, BLN, Salmon, M & Glen, RA 2015, Origin of lateral heterogeneities in the upper mantle beneath southeast Australia from seismic tomography. in A Khan & F Deschamps (eds), The Earth's Heterogeneous Mantle: A Geophysical, Geodynamical, and Geochemical Perspective. Springer Geosphysics, Springer , pp. 47-78. https://doi.org/10.1007/978-3-319-15627-9_2
Rawlinson N, Kennett BLN, Salmon M, Glen RA. Origin of lateral heterogeneities in the upper mantle beneath southeast Australia from seismic tomography. In Khan A, Deschamps F, editors, The Earth's Heterogeneous Mantle: A Geophysical, Geodynamical, and Geochemical Perspective. Springer . 2015. p. 47-78. (Springer Geosphysics). https://doi.org/10.1007/978-3-319-15627-9_2
Rawlinson, N ; Kennett, B L N ; Salmon, M ; Glen, R. A. / Origin of lateral heterogeneities in the upper mantle beneath southeast Australia from seismic tomography. The Earth's Heterogeneous Mantle: A Geophysical, Geodynamical, and Geochemical Perspective. editor / Amir Khan ; Frederic Deschamps. Springer , 2015. pp. 47-78 (Springer Geosphysics).
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N2 - We use teleseismic body wave tomography to reveal anomalous P wave velocity variations in the upper mantle beneath south-east Australia. Data are sourced from the WOMBAT transportable seismic array, the largest of its kind in the southern hemisphere, which enables horizontal resolution of approximately 50 km to be achieved over a large region that includes Victoria, New South Wales and southern South Australia. In order to account for long-wavelength structure that is lost due to the use of multiple teleseismic datasets from adjacent arrays with non-overlapping recording periods, the AuSREM mantle model is included as prior information in the inversion. Furthermore, AuSREM crust and Moho structure is explicitly included in the initial model in order to account for the presence of shallow heterogeneity which is poorly constrained by the teleseismic dataset. The P wave velocity model obtained from the joint inversion of WOMBAT teleseismic data represents a vast new resource on the seismic structure of the upper mantle beneath south-east Australia. One of the most striking features of the model is the presence of a north-dipping low-velocity anomaly beneath the Newer Volcanics province, a Quaternary intraplate basaltic province in western Victoria. The anomaly appears to terminate at approximately 200 km depth and has a structure that is more suggestive of a source confined to the upper mantle rather than a deeply rooted mantle plume. Other features that can be observed include a high-velocity anomaly beneath the Curnamona province and a high-velocity salient beneath the New England Orogen . Of particular interest is an extensive high-velocity anomaly beneath the Lachlan Orogen, which coincides almost exactly with the surface expression of the Hay–Booligal Zone in the south, and extends northwards beneath the Macquarie Arc. The higher velocities beneath the Hay–Booligal Zone are consistent with the idea that it may be floored by a fragment of Proterozoic continental lithosphere that was once part of the east Gondwana margin, while the higher velocities beneath the Macquarie Arc may be related to its origin as an intra-oceanic arc.

AB - We use teleseismic body wave tomography to reveal anomalous P wave velocity variations in the upper mantle beneath south-east Australia. Data are sourced from the WOMBAT transportable seismic array, the largest of its kind in the southern hemisphere, which enables horizontal resolution of approximately 50 km to be achieved over a large region that includes Victoria, New South Wales and southern South Australia. In order to account for long-wavelength structure that is lost due to the use of multiple teleseismic datasets from adjacent arrays with non-overlapping recording periods, the AuSREM mantle model is included as prior information in the inversion. Furthermore, AuSREM crust and Moho structure is explicitly included in the initial model in order to account for the presence of shallow heterogeneity which is poorly constrained by the teleseismic dataset. The P wave velocity model obtained from the joint inversion of WOMBAT teleseismic data represents a vast new resource on the seismic structure of the upper mantle beneath south-east Australia. One of the most striking features of the model is the presence of a north-dipping low-velocity anomaly beneath the Newer Volcanics province, a Quaternary intraplate basaltic province in western Victoria. The anomaly appears to terminate at approximately 200 km depth and has a structure that is more suggestive of a source confined to the upper mantle rather than a deeply rooted mantle plume. Other features that can be observed include a high-velocity anomaly beneath the Curnamona province and a high-velocity salient beneath the New England Orogen . Of particular interest is an extensive high-velocity anomaly beneath the Lachlan Orogen, which coincides almost exactly with the surface expression of the Hay–Booligal Zone in the south, and extends northwards beneath the Macquarie Arc. The higher velocities beneath the Hay–Booligal Zone are consistent with the idea that it may be floored by a fragment of Proterozoic continental lithosphere that was once part of the east Gondwana margin, while the higher velocities beneath the Macquarie Arc may be related to its origin as an intra-oceanic arc.

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