Complicated Lithospheric Structure Beneath the Contiguous US Revealed by Teleseismic S‐Reflections

Liu, Tianze; Shearer, Peter M.

doi:10.1029/2020jb021624

Cited by 21 publications

(79 citation statements)

References 39 publications

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“…Wang et al, 2022). (c) Receiver function studies revealed a relatively shallow Moho and shallow lithosphere-asthenosphere boundary beneath the NMSZ (T. Liu & Shearer, 2021;Ma & Lowry, 2017;McGlannan & Gilbert, 2016), which reflects a weak and thinned lithosphere. Moreover, Thomas and Powell (2017) proposed that most intraplate seismic zones are developed from ancient rifts or tectonic sutures, which happened for all the three seismic zones (i.e., NMSZ, ETSZ, and SCSZ) in the CEUS.…”

Section: Formation Of the Intraplate Seismic Zonesmentioning

confidence: 99%

Mantle Tomography of Central‐Eastern USA: Influence of Inversion Volume Size

et al. 2022

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The central and eastern United States (CEUS), inherited from Laurentia, has a thick, stable, and old continental lithosphere. The continental lithosphere, that is, the North American Craton (NAC), has remained stable for over 1.3 Ga despite subsequent reworking and deformation with the assembly and breakup of the Rodina and Pangaea supercontinents. In the past decade, seismic velocity structure of the crust and lithospheric mantle beneath the North American continent has been investigated by several techniques, including body wave tomography (

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Section: Formation Of the Intraplate Seismic Zonesmentioning

confidence: 99%

Mantle Tomography of Central‐Eastern USA: Influence of Inversion Volume Size

et al. 2022

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“…Therefore, variations in the Ssds traveltime are primarily due to seismic structure in the upper mantle beneath the seismic stations. There is no source-side and receiver side ambiguity if the analysis is limited to earthquakes deeper than the reflecting boundaries of interest (Liu and Shearer, 2021) but the data set would be significantly smaller.…”

Section: Mapping Of the 410 And 660 By 1-d Common Reflection Point Im...mentioning

confidence: 99%

Influence of shear wave velocity heterogeneity on SH-wave reverberation imaging of the mantle transition zone

Liu

Ritsema

Chaves

2022

Geophysical Journal International

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Summary Long-period (T > 10 s) shear-wave reflections between the surface and reflecting boundaries below seismic stations are useful for studying phase transitions in the mantle transition zone (MTZ) but shear-velocity heterogeneity and finite-frequency effects complicate the interpretation of waveform stacks. We follow up on a recent study by Shearer & Buehler (2019) (SB19) of the top-side shear-wave reflection Ssds as a probe for mapping the depths of the 410-km and 660-km discontinuities beneath the USArray. Like SB19, we observe that the recorded Ss410s-S and Ss660s-S traveltime differences are longer at stations in the western US than in the central-eastern US. The 410-km and 660-km discontinuities are about 40–50 km deeper beneath the western US than the central-eastern US if Ss410s-S and Ss660s-S traveltime differences are transformed to depth using a common-reflection point (CRP) mapping approach based on a 1-D seismic model (PREM in our case). However, the east-to-west deepening of the MTZ disappears in the CRP image if we account for 3-D shear-wave velocity variations in the mantle according to global tomography. In addition, from spectral-element method synthetics, we find that ray theory overpredicts the traveltime delays of the reverberations. Undulations of the 410-km and 660-km discontinuities are underestimated when their wavelengths are smaller than the Fresnel zones of the wave reverberations in the MTZ. Therefore, modeling of layering in the upper mantle must be based on 3-D reference structures and accurate calculations of reverberation traveltimes.

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“…Due to the influence of thick sedimentary layers atop the crust in the Atlantic and Gulf coastal plains, it is difficult to reliably image crustal and upper‐mantle structure using RF analysis or surface wave tomography alone, leading to occasionally conflicting crustal thickness and lithospheric velocity measurements. Additionally, many of the recent studies on crustal and upper mantle properties either target the entire contiguous United States (e.g., Buehler & Shearer, 2017; Liu & Shearer, 2021; Ma & Lowry, 2017; Shen & Ritzwoller, 2016; Yuan et al., 2014), or along densely spaced profiles (e.g., Hopper et al., 2016; Li et al., 2020; MacDougall et al., 2015; Parker et al., 2013; Verellen et al., 2020). There are only a limited number of post‐USArray studies on crustal and mantle structure focusing on the SEUS (e.g., Biryol et al., 2016; Hopper et al., 2017; Wagner et al., 2018), among which none has used the RF and Rayleigh wave dispersion joint inversion technique that this study employs.…”

Section: Introductionmentioning

confidence: 99%

“…Surface wave tomography studies (e.g., Bensen et al., 2008; Gaite et al., 2012; Porter et al., 2016; Spica et al., 2016) image low velocity anomalies in the upper crust beneath the Gulf Coastal Plain, which are attributed to the thick sediments (up to 10 km thick, Laske & Masters, 1997). RF and seismic tomography studies indicate that compared with the SAM, the Atlantic and Gulf of Mexico coastal plains possess relatively thin crust, in the range of ∼25–35 km (Buehler & Shearer, 2017; Li et al., 2020; Liu & Shearer, 2021; Ma & Lowry, 2017; Shen & Ritzwoller, 2016). With the exception of the central Suwannee Terrane, the observed

κ

values in the coastal plains and most part of the Suwannee Terrane are generally greater than 1.80 (Ma & Lowry, 2017), which are higher than the global average value of 1.78 for continental crust (Christensen, 1996) and thus may indicate a mafic composition.…”

Section: Introductionmentioning

confidence: 99%

Crustal and Upper Mantle Structure Beneath the Southeastern United States From Joint Inversion of Receiver Functions and Rayleigh Wave Dispersion

et al. 2021

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Using data from 186 stations belonging to the USArray Transportable Array, a three‐dimensional shear wave velocity model for the southeastern United States is constructed for the top 180 km by a joint inversion of receiver functions and Rayleigh wave phase velocity dispersion computed from ambient noise and teleseismic earthquake data. The resulting shear wave velocity model and the crustal thickness and Vp/Vs (κ) measurements show a clear spatial correspondence with major surficial geological features. The distinct low velocities observed in the depth range of 0–25 km beneath the eastern Gulf Coastal Plain reflect the thick layer of unconsolidated or poorly consolidated sediments atop the crystalline crust. The low κ (1.70–1.74) and slow lowermost crustal velocities observed beneath the eastern Southern Appalachian Mountains (including the Carolina Terrane and Inner Piedmont) relative to the adjacent Blue Ridge Mountains and Valley and Ridge can be interpreted by lower crustal delamination followed by relamination. The Osceola intrusive complex in the central Suwannee Terrane has similar crustal characteristics as the eastern Southern Appalachian Mountains and thus can similarly be attributed to crustal delamination/relamination processes. The Grenville Province and adjacent areas possess relatively high κ values which can be attributed to mafic intrusion associated with crustal extension in a recently recognized segments of the eastern arm of the Proterozoic Midcontinent Rift.

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Complicated Lithospheric Structure Beneath the Contiguous US Revealed by Teleseismic S‐Reflections

Cited by 21 publications

References 39 publications

Mantle Tomography of Central‐Eastern USA: Influence of Inversion Volume Size

Mantle Tomography of Central‐Eastern USA: Influence of Inversion Volume Size

Influence of shear wave velocity heterogeneity on SH-wave reverberation imaging of the mantle transition zone

Crustal and Upper Mantle Structure Beneath the Southeastern United States From Joint Inversion of Receiver Functions and Rayleigh Wave Dispersion

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