Anisotropic Tomography and Dynamics of the Big Mantle Wedge

Liang, Xuran; Zhao, Dapeng; Xu, Yi–Gang; Hua, Yilei

doi:10.1029/2021gl097550

Cited by 32 publications

(22 citation statements)

References 87 publications

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“…Because the FVDs are distributed in a wide region, we consider that they reflect mantle flow around the bottom of the upper mantle. This kind of large‐scale mantle flow was firstly observed in NE Asia from Vp anisotropic tomography (Wei et al., 2015), which was regarded as the cause of local inclined upwelling (Wei, Hammond, et al., 2019) to feed the intraplate volcanism in northeast China (Jia et al., 2022; Liang et al., 2022; Zhao, 2004). This observation is confirmed by recent SWS measurements at long‐period permanent stations (Guo et al., 2021).…”

Section: Discussionmentioning

confidence: 96%

Complex Patterns of Mantle Flow in Eastern SE Asian Subduction Zones Inferred From P‐Wave Anisotropic Tomography

Wei

Zhao

2022

JGR Solid Earth

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In subduction zones, the subduction of oceanic plates would drive complex mantle flow with a pattern affected by several factors, including the thermal structure of the subducting slab, the slab shape, the overriding plate thickness, and the viscosity of the surrounding mantle (e.g., Funiciello et al., 2003;Jadamec & Billen, 2010;Stegman et al., 2006). For a single slab subduction system, the dominant flow regimes include 2-D corner flow in the mantle wedge and subslab domain induced by viscous coupling between the subducting slab and the surrounding mantle (e.g., Kincaid & Sacks, 1997;Van Keken et al., 2002), and 3-D toroidal flow invoked by slab rollback (e.g., Faccenda & Capitanio, 2012;Long & Silver, 2008). The flow pattern may become more complicated when considering interactions of multiple subducting slabs as revealed by recent numerical modeling studies (e.g., Di Leo et al., 2014;Holt et al., 2017;Király et al., 2018). The eastern SE Asia region represents one of the ideal places for studying dynamics and evolution of subduction zones because of its long-lived subduction history and the assembly of slab subduction at various stages (Figure 1) (e.g., Hall, 2002;Yin, 2010). In its northern part, the Philippine region is characterized by the presence of active subduction zones on its both sides. To the west, the South China Sea (SCS), Sulu Sea, and Celebes Basins are subducting beneath the Philippine archipelago along

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Section: Discussionmentioning

confidence: 96%

Complex Patterns of Mantle Flow in Eastern SE Asian Subduction Zones Inferred From P‐Wave Anisotropic Tomography

Wei

Zhao

2022

JGR Solid Earth

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“…Nevertheless, AAN is widespread in the MTZ, which is detected by global long‐period surface wave overtones (Trampert & van Heijst, 2002; Yuan & Beghein, 2013). Many regional tomographic models also show strong anisotropy in the MTZ in the vicinity of subduction zones, for example, the big mantle wedge beneath East Asia (Jia et al., 2022; Liang, Zhao, Xu, & Hua, 2022; Ma et al., 2019; Wei et al., 2015, 2016), and SE Asia (Hua et al., 2022; Huang et al., 2015; Wei et al., 2022). In the uppermost lower mantle (660–1,000 km depths), anisotropy is also visible in both SWS measurements and anisotropic tomography (Gou et al., 2019; Hua et al., 2022; Huang et al., 2015; Lynner & Long, 2015; Nowacki et al., 2015; Zhao, 2021).…”

Section: Discussionmentioning

confidence: 99%

Seismic Anisotropy Tomography and Mantle Dynamics of Central‐Eastern USA

et al. 2022

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We present high‐resolution 3‐D tomographic models of isotropic P‐wave velocity (Vp), azimuthal anisotropy, and radial anisotropy down to 1,300 km depth beneath the central and eastern United States (CEUS), which are obtained by inverting a great number of local and teleseismic data and making a whole‐mantle correction to teleseismic travel‐time data recorded by the USArray. Trade‐offs between azimuthal and radial anisotropies occur due to the correlation between the azimuthal and incidence angles of seismic rays, but the use of uniform and crisscrossing rays can reduce the trade‐off effect. Our tomographic images reveal the North American Craton with layered anisotropy and strong anisotropies in the lower mantle related to the deeply subducted Farallon slab and passage of the Bermuda hotspot. In the upper mantle, low‐velocity anomalies with significant seismic anisotropy are revealed beneath three intraplate seismic zones in New Madrid, East Tennessee, and South Carolina, suggesting that hot and wet mantle upwelling occurs under the seismic zones, and the related fluids affect the earthquake generation. The most important dynamic processes in the mantle beneath the CEUS are the deep subduction of the Farallon plate and the passage of the Bermuda hotspot, which have caused strong structural heterogeneities, seismic anisotropy, as well as thermal anomalies and fluids that contributed to the formation of intraplate seismic zones in the CEUS.

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“…During the past decade, the RAN tomographic method has been applied extensively to study the 3-D Vp structure and dynamics of the crust and upper mantle in many regions, including NE Japan (Wang and Zhao 2013;Ishise et al 2018), SW Japan (Wang and Zhao 2013), South Kuril (Niu et al 2016), Eastern China (Wang et al 2014;Jiang et al 2021;Liang et al 2022), Tibet (Zhang et al 2021), the Philippines (Fan and Zhao 2019), Alaska (Gou et al 2019a), Cascadia (Zhao and Hua 2021), Southern California (Yu and Zhao 2018;Yu et al 2020b), Alps (Hua et al 2017), Africa (Yu et al 2020a), Greenland (Toyokuni and Zhao 2021), and Antarctica (Zhang et al 2020).…”

Section: Radial Anisotropy Tomographymentioning

confidence: 99%

“…5). This feature reflects mantle flows in the big mantle wedge (BMW) above the northwestward subducting Pacific slab and the stagnant slab in the mantle transition zone (MTZ) under East Asia (Zhao et al 2004(Zhao et al , 2009Lei and Zhao 2005;Chen et al 2017;Liang et al 2022;Cloetingh et al 2022). The hot and wet (Wei et al 2016).…”

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confidence: 99%

“…In the past one and a half decades, a number of researchers have used the AAN tomographic methods to study the 3-D Vp structure and dynamics of many subduction zones, including New Zealand (Eberhart-Phillips and Henderson 2004; Eberhart-Phillips and Reyners 2009), NE Japan (Wang and Zhao 2008;Cheng et al 2011;Ishise et al 2018Ishise et al , 2021, SW Japan (Ishise and Oda 2008;Wang and Zhao 2012, 2013), South Kuril (Koulakov et al 2015aNiu et al 2016;Gou et al 2019b;Liu et al 2013), NW Pacific (Wei et al 2015;Ma et al 2019;Liang et al 2022), Taiwan-Philippine (Koulakov et al 2015b;Zhao 2019, 2021a), SE Asia (Koulakov et al 2009;Hua et al 2022;Wei et al 2022), Alaska (Tian and Zhao 2012;Gou et al 2019a), Cascadia (Zhao and Hua 2021), Central America (Rabbel et al 2011), Chile (Huang et al 2019), the Eastern Mediterranean and Middle East (Wei et al 2019), and Alps (Hua et al 2017;Rappisi et al 2022).…”

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confidence: 99%

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Seismic Anisotropy Tomography and Mantle Dynamics

et al. 2023

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Seismic anisotropy tomography is the updated geophysical imaging technology that can reveal 3-D variations of both structural heterogeneity and seismic anisotropy, providing unique constraints on geodynamic processes in the Earth’s crust and mantle. Here we introduce recent advances in the theory and application of seismic anisotropy tomography, thanks to abundant and high-quality data sets recorded by dense seismic networks deployed in many regions in the past decades. Applications of the novel techniques led to new discoveries in the 3-D structure and dynamics of subduction zones and continental regions. The most significant findings are constraints on seismic anisotropy in the subducting slabs. Fast-velocity directions (FVDs) of azimuthal anisotropy in the slabs are generally trench-parallel, reflecting fossil lattice-preferred orientation of aligned anisotropic minerals and/or shape-preferred orientation due to transform faults produced at the mid-ocean ridge and intraslab hydrated faults formed at the outer-rise area near the oceanic trench. The slab deformation may play an important role in both mantle flow and intraslab fabric. Trench-parallel anisotropy in the forearc has been widely observed by shear-wave splitting measurements, which may result, at least partly, from the intraslab deformation due to outer-rise yielding of the incoming oceanic plate. In the mantle wedge beneath the volcanic front and back-arc areas, FVDs are trench-normal, reflecting subduction-driven corner flows. Trench-normal FVDs are also revealed in the subslab mantle, which may reflect asthenospheric shear deformation caused by the overlying slab subduction. Toroidal mantle flow is observed in and around a slab edge or slab window. Significant azimuthal and radial anisotropies occur in the big mantle wedge beneath East Asia, reflecting hot and wet upwelling flows as well as horizontal flows associated with deep subduction of the western Pacific plate and its stagnation in the mantle transition zone. The geodynamic processes in the big mantle wedge have caused craton destruction, back-arc spreading, and intraplate seismic and volcanic activities. Ductile flow in the middle-lower crust is clearly revealed as prominent seismic anisotropy beneath the Tibetan Plateau, which affects the generation of large crustal earthquakes and mountain buildings.

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Anisotropic Tomography and Dynamics of the Big Mantle Wedge

Cited by 32 publications

References 87 publications

Complex Patterns of Mantle Flow in Eastern SE Asian Subduction Zones Inferred From P‐Wave Anisotropic Tomography

Complex Patterns of Mantle Flow in Eastern SE Asian Subduction Zones Inferred From P‐Wave Anisotropic Tomography

Seismic Anisotropy Tomography and Mantle Dynamics of Central‐Eastern USA

Seismic Anisotropy Tomography and Mantle Dynamics

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