The seismological signature of temperature and grain size variations in the upper mantle

Faul, U.; Jackson, Ian

doi:10.1016/j.epsl.2005.02.008

Cited by 467 publications

(556 citation statements)

References 68 publications

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“…Mckenzie, 1967;Parker and Oldenburg, 1973;Parsons and Sclater, 1977;Stein and Stein, 1992). The increase in shear velocity of the uppermost mantle with increasing age observed with surface wave dispersion is also well described by these simple thermal models that predict deepening of isotherms in proportion to the square root of age in young seafloor (Faul and Jackson, 2005;Forsyth, 1975;Kausel et al, 1974;Maggi et al, 2006;Nishimura and Forsyth, 1988;Ritzwoller et al, 2004).…”

Section: Introductionmentioning

confidence: 58%

“…As pointed out by many of these authors and others, the presence of water and/or melt in the asthenosphere and a dehydrated lithosphere following extraction of melt are probably necessary to explain the pattern of velocity and conductivity anomalies. Nevertheless, some recent studies have suggested that neither the effects of melt nor water are required to explain the seismological observations if the non-linear, anelastic effects of attenuation due to changes in temperature or grain size on velocity are considered within the context of cooling plate or cooling half-space models (Faul and Jackson, 2005;Priestley and McKenzie, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Thickening of young Pacific lithosphere from high-resolution Rayleigh wave tomography: A test of the conductive cooling model

Harmon

Forsyth

Weeraratne

2009

Earth and Planetary Science Letters

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a b s t r a c t a r t i c l e i n f oDirect seismic measurements of the thickening of oceanic lithosphere away from the spreading axis are rare due to the remoteness of mid ocean ridges. On the East Pacific Rise, at 17°S, there were two long-term broadband ocean bottom seismometer deployments, the MELT and GLIMPSE experiments. These arrays spanned young Pacific plate seafloor ranging in age from 0 to 8 Ma. Combining these two data sets, we describe the increase in Rayleigh wave phase velocities for 16-100 s period as function of distance from the ridge with two parameterizations: an arbitrary function of seafloor age and a simple polynomial function of age on the Pacific and Nazca plates. Although resolution analysis shows that 10 to 15 independent pieces of information about the age variation of phase velocity on the Pacific plate can be resolved at periods of ≤50 s, the three parameter polynomial model fits the data almost as well, indicating a simple pattern of the evolution of structure with age. To compare our observations to the predictions for the conductive cooling of the lithosphere, we convert a thermal half-space cooling model to shear velocity using anharmonic and anelastic contributions. The patterns in the velocities are not consistent with simple conductive cooling. The conductive cooling model under predicts the changes in phase velocity with age observed in the 20 to 78 s period range. We observe significant changes in shear velocity in the asthenosphere at depths greater than conductive cooling should extend. The asthenospheric low velocity zone is asymmetric, dipping to the west with the lowest velocities beneath the Pacific plate west of the spreading center. The conductive cooling model also over predicts the shear velocities in the lithosphere by~0.2 km/s. These anomalies indicate that more complicated mantle flow and significant mantle heterogeneities such as melt are required.

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Section: Introductionmentioning

confidence: 58%

Section: Introductionmentioning

confidence: 99%

Thickening of young Pacific lithosphere from high-resolution Rayleigh wave tomography: A test of the conductive cooling model

Harmon

Forsyth

Weeraratne

2009

Earth and Planetary Science Letters

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“…[7] The importance of the physical properties on the seismic attenuation parameters have been demonstrated in experimental studies applied to environmental and petrological conditions of the upper mantle [e.g., Jackson et al, [Jackson et al, 2002;Faul and Jackson, 2005], partial melting and the water content [Aizawa et al, 2008] play a crucial role in the attenuation of the seismic waves propagating in the upper mantle. The Q P M calculated in the frequency range between 0.25 and 8 Hz and the Q S M values for frequencies from 0.25 to 2 Hz (Figure 3) are low (Q P M = 74 and Q S M = 96 at 1 Hz), similar to the quality factors measured in high attenuation crustal domains.…”

Section: Resultsmentioning

confidence: 99%

Q_P and Q_S in the upper mantle beneath the Iberian peninsula from recordings of the very deep Granada earthquake of April 11, 2010

Mancilla

Pezzo

Stich

et al. 2012

Geophysical Research Letters

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[1] Granada (Southern Spain) is a place of rare and enigmatic very deep focus earthquakes, the last one on April 11, 2010, with magnitude of 6.3 and depth of 620 km. We use regional broadband recordings to estimate Q P and Q S in the mantle for frequencies between 0.25 and 8 Hz, computing the spectra of the direct P-and S-waves with their early P-and S coda. We use the spectral decay method, constraining crustal Q to values given in the literature. We obtain robust estimates of Q P in 6 frequency bands (0.25, 0.5,1, 2, 4 and 8 Hz) and of Q S in 4 bands (0.25, 0.5,1, 2 Hz). Q P in the mantle ranges from 13 at 0.25 Hz to 346 at 8 Hz and Q S from 59 at 0.25 to 183 at 2 Hz. The frequency dependence is well fitted by Q = Q 0 f a with a equal to 0.6 for Q S and 1.0 for Q P , and Q 0 equal to 109 for Q S and 63 for Q P . The Q P /Q S ratio is less than 1. These are extreme values within the ranges of mantle Q, Q P /Q S and a values reported in the literature, indicating strong scattering attenuation and absence of melt. We propose that such values, rather than being an exception, may approximate the average upper mantle, with solid olivine composition and small-scale heterogeneity.

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“…[45] In the upper mantle, temperature is the primary cause of perturbations in wave speed at a fixed depth; variability in rock and mineral composition has a smaller effect [e.g., Lee, 2003;Shapiro and Ritzwoller, 2004;Faul and Jackson, 2005]. Recent seismic images of the upper mantle across northwestern Canada have been obtained from teleseismic body waves [e.g., Mercier et al, 2008Mercier et al, , 2009] and surface waves [Frederiksen et al, 2001; van der Lee and Frederiksen, 2005;Nettles and Dziewonski, 2008].…”

Section: Discussionmentioning

confidence: 99%

CrustalV_Sstructure in northwestern Canada: Imaging the Cordillera-craton transition with ambient noise tomography

Dalton¹,

Gaherty²,

Courtier³

2011

J. Geophys. Res.

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Crustal seismic velocity structure in northwest Canada is imaged using group velocity measurements derived from ambient noise cross correlations. The focus area surrounds the Canadian Northwest Experiment (CANOE) array, a 16 month deployment of 59 broadband seismic stations. The CANOE array extended from the Northern Cordillera on the west into the Archean Slave province to the east, crossing crustal terranes that span ∼4 Gyr of Earth history. Forty broadband stations from the Canadian National Seismograph Network and the POLARIS network are also included. The Green's function for each pair of stations is estimated by cross‐correlating 24 h long time series of ambient noise for each day in the time period July 2004 to June 2005. Fundamental mode Rayleigh waves are observed on cross‐correlated vertical component records and Love waves on the transverse components. The group velocity measurements are inverted for 3‐D shear wave velocity within the crust. Local sensitivity kernels are used to account for the effects of a laterally variable sedimentary layer at shallow depths, and receiver function P‐s differential times at the CANOE stations constrain total crustal thickness. Known sedimentary basins dominate lateral variations in wave speed in the shallow crust. In the middle crust, the model contains a strong low‐velocity region that correlates spatially with the location of Proterozoic metasedimentary rocks that have been inferred from active source reflection profiles to occupy much of the crust beneath the Cordilleran terranes. Velocity variations in the lower crust, which are weakly resolved due to the limited period range of our data set (5–20 s), suggest a west‐to‐east transition from lower to higher wave speeds that aligns with the Cordilleran deformation front in parts of the study area. The results presented here are consistent with but do not confirm the notion of Proterozoic strata throughout much of the Cordilleran crust. These metasedimentary rocks, if present, must have experienced some deformation and metamorphism in order to also be consistent with upper mantle seismic models that contain a sharp transition from low to high velocity across the deformation front.

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The seismological signature of temperature and grain size variations in the upper mantle

Cited by 467 publications

References 68 publications

Thickening of young Pacific lithosphere from high-resolution Rayleigh wave tomography: A test of the conductive cooling model

Thickening of young Pacific lithosphere from high-resolution Rayleigh wave tomography: A test of the conductive cooling model

Q_P and Q_S in the upper mantle beneath the Iberian peninsula from recordings of the very deep Granada earthquake of April 11, 2010

CrustalV_Sstructure in northwestern Canada: Imaging the Cordillera-craton transition with ambient noise tomography

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The seismological signature of temperature and grain size variations in the upper mantle

Cited by 467 publications

References 68 publications

Thickening of young Pacific lithosphere from high-resolution Rayleigh wave tomography: A test of the conductive cooling model

Thickening of young Pacific lithosphere from high-resolution Rayleigh wave tomography: A test of the conductive cooling model

QP and QS in the upper mantle beneath the Iberian peninsula from recordings of the very deep Granada earthquake of April 11, 2010

CrustalVSstructure in northwestern Canada: Imaging the Cordillera-craton transition with ambient noise tomography

Contact Info

Product

Resources

About

Q_P and Q_S in the upper mantle beneath the Iberian peninsula from recordings of the very deep Granada earthquake of April 11, 2010

CrustalV_Sstructure in northwestern Canada: Imaging the Cordillera-craton transition with ambient noise tomography