Inferring upper-mantle temperatures from seismic velocities

Cammarano, Fabio; Goes, Saskia; Vacher, Pierre; Giardini, Domenico

doi:10.1016/s0031-9201(03)00156-0

Cited by 517 publications

(647 citation statements)

References 126 publications

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“…Midoceanic ridges, known to be hotter than average, are seismically slower than average; the cooling of the oceanic lithosphere with age appears as progressively faster wave speeds away from the midoceanic ridge systems; and ancient continental shields are in general marked by low average heat flow and faster than average seismic propagation speed. This is consistent with analyses of mineral physics data, which show that at shallow depths in the mantle, seismic velocities are generally much less sensitive to composition than to variations in temperature [Deschamps et al, 2002;Cammarano et al, 2003]. However, chemical depletion of subcontinental lithosphere [e.g., the tectosphere hypothesis of Jordan, 1975] can lead to small detectable changes in wave speeds identifiable by considering decorrelations between P-and S-wave tomography [Goes et al, 2000], combined tomography and gravity data [Forte and Perry, 2000;Deschamps et al, 2002;van Gerven et al, 2004] and seismic anisotropy [Beghein and Trampert, 2004].…”

Section: Origin Of Wave Speed Anomalies: Demise Of the Thermal Paradigmsupporting

confidence: 83%

Towards a quantitative interpretation of global seismic tomography

Trampert

Hilst

2005

Geophysical Monograph Series

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We review the success of seismic tomography in delineating spatial variations in the propagation speed of seismic waves on length scales from several hundreds to many thousands of kilometers. In most interpretations these wave speed variations are thought to reflect variations in temperature. Careful consideration of shear wave, bulk sound, and, most recently, density variations is, however, producing increasingly compelling evidence for chemical heterogeneity (that is, spatial variations in bulk major element composition) having a first-order effect on the lateral variations in mass density and elasticity of the mantle. This has profound consequences for our understanding of mantle dynamics and the thermochemical evolution of our planet. We argue that the quantitative integration of constraints from seismology, mineral physics, and geodynamics, which underlies the inference of thermochemical parameters, requires careful uncertainty analyses and should move away from emphasizing visually pleasing images and single, nonunique solutions.

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Section: Origin Of Wave Speed Anomalies: Demise Of the Thermal Paradigmsupporting

confidence: 83%

Towards a quantitative interpretation of global seismic tomography

Trampert

Hilst

2005

Geophysical Monograph Series

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“…This method, which is distinct from but complements geothermal modeling of heat flow data, provides a means to estimate the 3D upper-mantle temperature structure from measured seismic velocities. This temperature estimation method has been successfully applied in the studies of several continents (Cammarano et al, 2003;Goes and Van der Lee, 2002;Goes et al, 2000;Rohm et al, 2000;Shapiro and Ritzwoller, 2004). An and Shi (2006) calculated the 3D upper-mantle temperature structure of the Chinese continent from seismic velocities measurements in 3D, and used these results to estimate the lithospheric thickness on a 1°× 1°grid, as shown in Fig.…”

Section: Gravitational Effect Of the Undulated Mantle Lithospherementioning

confidence: 99%

Mantle origin of the Emeishan large igneous province (South China) from the analysis of residual gravity anomalies

Deng

Zhang

Mooney

et al. 2014

Lithos

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“…By adding constraints from gravity or geoid data, joint inversions for seismic velocity and density have been performed because of the better chance to isolate thermal and compositional effects (11-13). Whereas temperature sensitivity dominates for seismic velocities, especially at shallow depths (7,14,15), density also strongly varies with composition.Besides the trade-off between temperature and composition, an important issue for seismic interpretation concerns the fact that a seismic model is not required to have a meaning in terms of these physical parameters.Typically, the interpretation of a given seismic data set is performed in two steps. First, a seismic model is constructed that fits the data satisfactorily.…”

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Insights into the nature of the transition zone from physically constrained inversion of long-period seismic data

Cammarano¹,

Romanowicz²

2007

Proc. Natl. Acad. Sci. U.S.A.

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Imposing a thermal and compositional significance to the outcome of the inversion of seismic data facilitates their interpretation. Using long-period seismic waveforms and an inversion approach that includes constraints from mineral physics, we find that lateral variations of temperature can explain a large part of the data in the upper mantle. The additional compositional signature of cratons emerges in the global model as well. Above 300 km, we obtain seismic geotherms that span the range of expected temperatures in various tectonic regions. Absolute velocities and gradients with depth are well constrained by the seismic data throughout the upper mantle, except near discontinuities. The seismic data are consistent with a slower transition zone and an overall faster shallow upper mantle, which is not compatible with a homogenous dry pyrolite composition. A gradual enrichment with depth in a garnet-rich component helps to reduce the observed discrepancies. A hydrated transition zone would help to lower the velocities in the transition zone, but it does not explain the seismic structure above it.mantle composition ͉ seismology ͉ mineral physics T he thermal state and composition of Earth's upper mantle and transition zone dictate its dynamics from microscale (e.g., creep mechanisms and earthquakes) to macroscale (e.g., modality of mantle convection and plate tectonics). The knowledge of these fundamental physical parameters and their 3D variations in Earth's deep interior is indirect and relies entirely on the interpretation of geophysical data, based on insights from theoretical and experimental mineral physics. Among these data, seismological observations constitute a main source of information. Seismic waves record information about the elastic (and anelastic) structure of Earth. Long-period seismic data provide the most comprehensive global constraints on upper mantle shear velocity structure. Fundamental-mode surface waves are mostly sensitive to the uppermost mantle structure, and including overtones provides resolution in the transition zone.Lateral temperature variations in the Earth have been inferred since the first tomographic studies began to reconstruct 3D seismic velocity structure (1, 2). However, despite the everimproving resolution of seismic velocity models and a general agreement of different models on at least the large-scale structure (e.g., refs. 3-6), interpretation is still challenging. The few quantitative interpretation efforts made to date have shown that much of the seismic heterogeneity in the uppermost mantle is probably thermal in origin (7, 8), but it is likely that there is a compositional contribution under cratons (9, 10) and that fluids influence the very low velocities in the mantle wedge above subduction zones (8). By adding constraints from gravity or geoid data, joint inversions for seismic velocity and density have been performed because of the better chance to isolate thermal and compositional effects (11-13). Whereas temperature sensitivity dominates for seismic velociti...

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Inferring upper-mantle temperatures from seismic velocities

Cited by 517 publications

References 126 publications

Towards a quantitative interpretation of global seismic tomography

Towards a quantitative interpretation of global seismic tomography

Mantle origin of the Emeishan large igneous province (South China) from the analysis of residual gravity anomalies

Insights into the nature of the transition zone from physically constrained inversion of long-period seismic data

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