The deep structure of the Australian continent from surface wave tomography

Simons, Frederik J.; Zielhuis, Alet; Hilst, R. D. van der

doi:10.1016/s0419-0254(99)80003-2

Cited by 94 publications

(163 citation statements)

References 78 publications

Supporting

Mentioning

144

Contrasting

Order By: Relevance

“…Where data quality allowed we ¢tted the fundamental mode between 5 and 25 mHz (40^200 s period) or a narrower frequency band within this range, while the higher modes were ¢tted between 8 and 50 mHz (20^125 s). With these frequency bounds the fundamental modes can provide sensitivity to structure down to at least 400 km, and, within the limits of our theoretical assumptions, the higher modes yield additional detail [37,47].…”

Section: Datamentioning

confidence: 58%

“…The broadband seismic data collected by the Skippy experiment [45] have led to increasingly detailed knowledge of the wave-speed structure of the Australian upper mantle and its anisotropy [35^37, 46,47].…”

Section: Datamentioning

confidence: 99%

“…Fig. 1 depicts an isotropic background model used in the waveform ¢tting [47] (Fig. 1A) and the associated sensitivities of the (unweighted) sum of all the surface modes making up the seismogram (Fig.…”

Section: Depth Sensitivitymentioning

confidence: 99%

See 2 more Smart Citations

Seismic and mechanical anisotropy and the past and present deformation of the Australian lithosphere

Simons

Hilst

2003

Earth and Planetary Science Letters

Self Cite

View full text Add to dashboard Cite

We interpret the three-dimensional seismic wave-speed structure of the Australian upper mantle by comparing its azimuthal anisotropy to estimates of past and present lithospheric deformation. We infer the fossil strain field from the orientation of gravity anomalies relative to topography, bypassing the need to extrapolate crustal measures, and derive the current direction of mantle deformation from present-day plate motion. Our observations provide the depth resolution necessary to distinguish fossil from contemporaneous deformation. The distribution of azimuthal seismic anisotropy is determined from multi-mode surface-wave propagation. Mechanical anisotropy, or the directional variation of isostatic compensation, is a proxy for the fossil strain field and is derived from a spectral coherence analysis of digital gravity and topography data in two wavelength bands. The joint interpretation of seismic and tectonic data resolves a rheological transition in the Australian upper mantle. At depths shallower than V150^200 km strong seismic anisotropy forms complex patterns. In this regime the seismic fast axes are at large angles to the directions of principal shortening, defining a mechanically coupled crust^mantle lid deformed by orogenic processes dominated by transpression. Here, seismic anisotropy may be considered 'frozen', which suggests that past deformation has left a coherent imprint on much of the lithospheric depth profile. The azimuthal seismic anisotropy below V200 km is weaker and preferentially aligned with the direction of the rapid motion of the Indo-Australian plate. The alignment of the fast axes with the direction of present-day absolute plate motion is indicative of deformation by simple shear of a dry olivine mantle. Motion expressed in the hot-spot reference frame matches the seismic observations better than the no-net-rotation reference frame. Thus, seismic anisotropy supports the notion that the hot-spot reference frame is the most physically reasonable. Independently from plate motion models, seismic anisotropy can be used to derive a best-fitting direction of overall mantle shear. ß

show abstract

Section: Datamentioning

confidence: 58%

Section: Datamentioning

confidence: 99%

See 1 more Smart Citation

Seismic and mechanical anisotropy and the past and present deformation of the Australian lithosphere

Simons

Hilst

2003

Earth and Planetary Science Letters

Self Cite

View full text Add to dashboard Cite

show abstract

“…This range may be the unstable result of subtracting two comparable numbers to get mantle heat flow and dividing by this number to get lithospheric thickness. Bank et al, 1998;Ritsema et al, 1998;Simons et al, 1999;Priestley, 1999;Ritsema and van Heist, 2000]. The more reliable studies take explicit account of downward smearing of cratonal features, a well-known artifact of tomographic inversion.…”

Section: Heat Flow Studiesmentioning

confidence: 99%

“…The depth $230 km, where tomographic velocity anomalies approach resolution and cease to correlate which surface features, is a robust measure of seismic lithospheric thickness [Röhm et al, 2000]. It is shallower than 250 km in the studies by Simons et al [1999] and by Ritsema and van Heist [2000].…”

Section: Heat Flow Studiesmentioning

confidence: 99%

Survival of Archean cratonal lithosphere

2003

View full text Add to dashboard Cite

[1] I use thermal convection models to search for combinations of physical parameters that are compatible with the results of xenolith studies on the history and present thermal structure of cratonal lithosphere. The cratonal lithosphere above $180 km depth formed in the Archean and remained stable until recently sampled. The mantle adiabat cooled $150 K over this time. The temperature change across the rheologically active boundary layer at the lithospheric base is <300 K over a depth range of several tens of kilometers. Modern cratonal lithospheric thicknesses are relatively uniform, $225 km, much thicker than old oceanic lithosphere. Cratonal lithosphere is now in quasi-steady state with conductive heat flow to the surface in balance with heat supplied to the base of the lithosphere by convection driven by local temperature contrasts within the rheologically active boundary layer. This heat flow and the lithosphere thickness changed little after the cratonal lithosphere stabilized. One possibility is that chemically buoyant lithosphere forms a conductive lid above the convecting normal mantle. To survive, the chemical lithosphere also needs to be more viscous than normal mantle. A reasonable situation has chemical lithosphere a factor of 20 more viscous than normal mantle with weakly temperature-dependent viscosity (a factor of e over 100 K) from 0.2 Â 10 20 Pa s along the modern mantle adiabat. However, a chemical lid is unnecessary for lithospheric thickness to change slowly over time. For example, the base of the lithosphere may be stable if the viscosity at its base (along an adiabat) decreases rapidly with depth.

show abstract

A new algorithm for three‐dimensional joint inversion of body wave and surface wave data and its application to the Southern California plate boundary region

et al. 2016

View full text Add to dashboard Cite

We introduce a new algorithm for joint inversion of body wave and surface wave data to get better 3‐D P wave (Vp) and S wave (Vs) velocity models by taking advantage of the complementary strengths of each data set. Our joint inversion algorithm uses a one‐step inversion of surface wave traveltime measurements at different periods for 3‐D Vs and Vp models without constructing the intermediate phase or group velocity maps. This allows a more straightforward modeling of surface wave traveltime data with the body wave arrival times. We take into consideration the sensitivity of surface wave data with respect to Vp in addition to its large sensitivity to Vs, which means both models are constrained by two different data types. The method is applied to determine 3‐D crustal Vp and Vs models using body wave and Rayleigh wave data in the Southern California plate boundary region, which has previously been studied with both double‐difference tomography method using body wave arrival times and ambient noise tomography method with Rayleigh and Love wave group velocity dispersion measurements. Our approach creates self‐consistent and unique models with no prominent gaps, with Rayleigh wave data resolving shallow and large‐scale features and body wave data constraining relatively deeper structures where their ray coverage is good. The velocity model from the joint inversion is consistent with local geological structures and produces better fits to observed seismic waveforms than the current Southern California Earthquake Center (SCEC) model.

show abstract

The deep structure of the Australian continent from surface wave tomography

Cited by 94 publications

References 78 publications

Seismic and mechanical anisotropy and the past and present deformation of the Australian lithosphere

Seismic and mechanical anisotropy and the past and present deformation of the Australian lithosphere

Survival of Archean cratonal lithosphere

A new algorithm for three‐dimensional joint inversion of body wave and surface wave data and its application to the Southern California plate boundary region

Contact Info

Product

Resources

About