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3-D iso-surface representations of fast wavespeed anomalies with magnitude >1.5% (green bodies), and fast axes (yellow arrows) at a depth of 500 km in model US32 Topographic variations are superimposed on top of the 3-D iso-surface bodies. Fast anomalies shallower than 250 km, mainly the North and South American lithospheres, are clipped for better visualization of sinking slabs. Cyan arrows are used to highlight slab features, whereas orange arrows are used to denote mantle flow fields.
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Laboratory experiments and geodynamic simulations demonstrate that poloidal- and toroidal-mode mantle flows develop around subduction zones. Here, we use a new 3-D azimuthal anisotropy model constructed by full waveform inversion, to infer deep subduction-induced mantle flows underneath Middle America. At depths shallower than 150 km, poloidal-mode...
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We investigated the primary mechanisms triggering the S-wave splitting of 7 unusually deep local earthquakes (between 50km and 60km) that originated in the lithosphere beneath the Rwenzori region, in attempt to develop an understanding of the relationship between anisotropic structures in the lithosphere and tectonic deformation processes. A total...
New passive- and active-source seismic experiments reveal unusually high mantle P-wave speeds that extend beneath the remnants of the world’s largest known large igneous province, making up the 120-million-year-old Ontong-Java-Manihiki-Hikurangi Plateau. Sub-Moho P n phases of ~8.8 ± 0.2 km/s are resolved with negligible azimuthal seismic anisotrop...
Citations
... To date, some shear-wave splitting measurements have suggested the presence of prominent seismic anisotropy in the upper portion of the lower mantle (UPLM) beneath several subduction zones [11][12][13][14][15] . In addition, a whole-mantle shear-wave anisotropic model suggests a wide Article https://doi.org/10.1038/s41561-024-01404-6 ...
... The prominent N-S FVDs at 700-900-km depths beneath the middle PSP ( Fig. 2a-c) seem to be less affected by the slab subduction because they occur generally away from the present subduction zones. In addition, previous seismic anisotropy studies revealed that the UPLM is generally characterized by trench-parallel FVDs [11][12][13][14][15][16] , which are possibly caused by interactions between the subducted slab and the lower mantle inducing high differential stresses and dislocation creep 16 . Similarly, surface-wave anisotropic tomography revealed prominent anisotropies in the UPLM away from subduction zones beneath central Asia 26 . ...
Seismic anisotropy could provide vital information about the evolution and internal convection of the deep Earth interior. Although previous seismological studies have revealed a wide distribution of seismic anisotropy in the upper portion of the lower mantle beneath many subduction zones, the existence of anisotropy at these depths away from subducted slabs remains debated. Here we use P-wave azimuthal anisotropy tomography to image the crust and mantle down to 1,600-km depth. We find prominent anisotropic patterns in the upper portion of the lower mantle beneath the Philippine Sea Plate. Substantial azimuthal anisotropy with N–S fast-velocity directions occurs at 700–900-km depths. We interpret this azimuthal anisotropy as a remnant of the Pacific lower mantle flow field about 50 million years ago. Two isolated high-velocity anomalies at 700–1,600-km depths may be vestigial pieces of the subducted Izanagi slab with seismic velocity features suggesting a shift in the Pacific lower mantle flow field by about 40 million years ago. Our findings provide seismic evidence for the existence of complex lower mantle flows and deformation mechanisms away from subduction zones.
... Seismic anisotropy, a powerful tool for probing the Earth's interior, has been widely applied to constrain the deformation and dynamic processes of subduction zones in the past two decades (e.g., Castellanos et al., 2020; Eberhart-Phillips & Henderson, 2004;Liang et al., 2022;Liu & Zhao, 2017;Wang & Zhao, 2013Zhu et al., 2020). This feature manifests itself as some properties of seismic waves varying with the wave propagation direction resulting from a strain-induced preferential orientation of anisotropic materials in the Earth's interior (e.g., Karato et al., 2008;Park & Levin, 2002). ...
The 180°curvature of the Banda arc at the eastern end of the Java-Banda subduction zone reflects complicated geodynamic processes. A detailed investigation of its anisotropic structure would reveal its subduction dynamics, further resolving the controversial issue on how the highly arcuate Banda arc formed. We apply tilting-axis anisotropic tomography to obtain a high-resolution 3-D anisotropic model beneath the Java-Banda region. Our results show significant differences between Java and Banda in the pattern of anisotropy in both the subducting slab and its surrounding mantle, which reflect two distinctly different deformation modes in the two domains. Our results support the single-slab subduction model for the Banda region. In addition, trench-normal and upright fast-velocity-planes appear in the deep upper mantle, which may indicate material migrations in the big mantle wedge. Fast-velocity-planes in the shallow mantle exhibit a toroidal distribution, reflecting past counterclockwise rotation and asthenospheric material extrusion.
... The FGA is relatively sensitive to topography, the BGA after terrain correction exhibits a wide range of high values at the deep-sea basins, which masks some of the details, and the IGA is overall similar to the distribution of FGA, but has a relatively smaller amplitude (Fig. 2). In addition, the published crustal thickness (Chen et al., 2021) and the regional seismic tomographic models (Hosseini et al., 2020;Zhu et al., 2020) are also used for further interpretation and discussion. ...
... 27 Then, the COFs with different metal porphyrin or various linker phthalocyanine cores were developed to catalyze the CO 2 RR. 3,[27][28][29][30][31][32][33][34][35][36][37][38][39] However, the difficult for designing and synthesizing the catalytic building units hindered us further exploring the new catalytic centers in COFs for CO 2 RR. In addition to developing the functional COFs, COFs are also an ideal template to construct functional carbons because of their uniformly distributed atoms and high pore volumes. ...
Covalent organic frameworks (COFs) have been developed as the precursors to construct porous carbons for electrocatalytic systems. However, the influences of carbon dimensions on the catalytic performance are still underexplored. In this work, we have first constructed COF‐derived carbons by template‐synthesis strategy in different dimensions to catalyze the carbon dioxide reduction (CO 2 RR). By using different templates, the one‐dimensional (1D), two‐dimensional (2D), and three‐dimensional (3D) COF‐derived carbons have been employed to anchor Co‐porphyrin to form the Co‐N 5 sites to catalyze CO 2 RR. The 1D catalyst templated by carbon nano tubes presents high binding ability of CO 2 , more defective sites, and higher electronic conductivity, resulting in a higher catalytic activity for CO 2 and selectivity of CO than 2D and 3D carbon‐based catalysts. The 1D catalyst delivers the turnover frequency values of 1150 h ⁻¹ and the FECO of 94.5% at 0.7 V versus RHE, which is significantly better than those of 2D and 3D carbon‐based catalysts.
... The P-wave imaging results for this area are limited by the resolution, and often show only the large-scale low-velocity structure beneath the volcanic belt and high-velocity of the subduction plate. In some relatively new imaging results, the detailed information on the velocity structure directly related to the possible tearing of the Cocos plate is also not provided (Amaru, 2007;Hosseini et al., 2020;Li et al., 2008;Lu et al., 2019;van Benthem, Govers, et al., 2013;van der Hilst et al., 1997;Zhu et al., 2020). The existing shear-wave splitting research in this region can provide the overall anisotropic effect under the station (Bernal-Lopez et al., 2016;Castellanos et al., 2017;Celis et al., 2022;Soto et al., 2021;van Benthem, Valenzuela, & Ponce, 2013), but the spatial coverage and depth constraint are insufficient. ...
... The consistency of the results obtained from different data and methods supports the reliability of these results. However, although there is consensus between the imaging of the upper mantle provided by waveform inversion (Zhu et al., 2020) and our study on some large-scale structures, such as the observed high-velocity structure in Yucatan Block, significant low-velocity in southern Mexico, and the NE-SW anisotropy in the Cocos plate beneath the Pacific Ocean; However, in the waveform inversion results, the NE-SW anisotropy extends from the ocean to the coast of the Gulf of Mexico, and no arc-parallel anisotropy beneath the arc has been observed, and does not provide spatial changes in velocity structures associated with the complex plate subduction processes and potential tears in southern Mexico. We are not sure whether this is limited by the resolution or because its results contain structural information of different depths. ...
... The tear is an important factor for the significant difference in the form and angle of slab subduction on both sides and leads to the termination of the TMVB volcanic belt to the east. Some tomography results in a larger spatial do not reflect the difference in the velocity structure between the flat-slab subduction zone and the North and South Cocos plate subduction segments on both sides (Amaru, 2007;Gaite et al., 2012;Hosseini et al., 2020;Li et al., 2008;van Benthem, Govers, et al., 2013;Zhu et al., 2020), which may be due to the restriction of resolution. The uppermost mantle beneath the LTVF area in the northern part of Oaxaca area presents a relatively high-velocity structure (Figure 3a), which is consistent with previous studies (Castellanos et al., 2018;Chen & Clayton, 2012;Espindola-Corona et al., 2021), indicating that the LTVF may have a lack of vertical thermal material supply from the mantle. ...
Plain Language Summary
The collision and subduction of the Cocos and North American plates created a complex geological structure in southern Mexico. Although some scholars proposed that there are some tears in the subducted Cocos slab based on the research of seismic parameters, the support of seismic tomography research for tear models is insufficient. Here, we applied a unique Pn tomography method and obtained the first Pn velocity and anisotropy model of the uppermost mantle in southern Mexico. The study clarified the mid‐oceanic ridge‐perpendicular anisotropy of the Cocos oceanic plate and the trench‐parallel anisotropy beneath the subduction arc. The spatial variations in Pn velocity and anisotropic structure in southern Mexico provide new seismological constraints on the tears of the subducted Cocos plate corresponding to fracture zones. The observed low Pn velocity beneath the Trans‐Mexican Volcanic Belt and the northern area and the trench‐perpendicular anisotropy support the retreat model of the Central Cocos plate. Our study provides a new and reliable tomography basis for a complicated subduction dynamics process in the southern Mexico subduction zone and provides new constraints for a slab‐tearing model corresponding to the fracture zones and the slab retreat model of the Central Cocos plate.
... This model, however, is inconsistent with more recent tomographic images. A regional-scale full-waveform inversion study (Zhu et al., 2020) revealed a continuous Cocos slab extending from the surface to a depth of at least 1000 km. The same study also found that in the top 200 km, the velocity anomaly of the slab is significantly weaker than that in deeper sections of the slab (Fig. S2), consistent with the reduced seismicity around this depth (Fig. 2B). ...
... The same study also found that in the top 200 km, the velocity anomaly of the slab is significantly weaker than that in deeper sections of the slab (Fig. S2), consistent with the reduced seismicity around this depth (Fig. 2B). Additionally, at depths greater than 80 km, the dominant fast orientation of seismic anisotropy, which represents the mantle flow direction in the sublithospheric mantle, is different between the oceanic and continental sides (Zhu et al., 2020). Specifically, it is trench-perpendicular on the Cocos side and becomes east-west on the Caribbean side with a clear right-turn pattern (Fig. S3). ...
... In particular, the resulting fast orientations tend to be more perpendicular to the trench for ray paths arriving at the stations from the southwest, which sample the ocean side of the mantle, than those from other back azimuths. This pattern is consistent with a clockwise rotation of the inferred mantle flow directions that is also revealed by results from a full-waveform tomographic inversion (Zhu et al., 2020) (Fig. S3). Another notable feature is a sudden change in anisotropy orientations across the North American-Caribbean Plate boundaries, where results in the northern part are more trench-normal, which resembles typical corner flow. ...
Fundamental to plate tectonics is the subduction of cold and mechanically strong oceanic plates. While the subducted plates are conventionally regarded to be impermeable to mantle flow and separate the mantle wedge and the subslab region, isolated openings have been proposed. By combining new shear wave splitting measurements with results from geodynamic modeling and recent seismic tomography and geochemical observations, we show that the upper ∼200 km of the Cocos slab in northern Central America is intensively fractured. The slab there is strong enough to produce typical arc volcanoes and Benioff Zone earthquakes but allows mantle flow to traverse from the subslab region to the mantle wedge. Upwelling of hot subslab mantle flow through the slab provides a viable explanation for the behind-the-volcanic-front volcanoes that are geochemically distinct from typical arc volcanoes, and for the puzzling high heat flow, high elevation, and low Bouguer gravity anomalies observed in northern Central America.
... 3a, d-f). The continuity of the subducting slab is further supported by the existence of seismicity along the plate interface ( Figs. 1 and 3) and the detection of a typical corner flow within the mantle wedge of the southern Cocos plate 21 . Here we consider two primary factors that can significantly reduce the seismic velocity of the subducting slab near the trench. ...
A typical subduction of an oceanic plate beneath a continent is expected to be accompanied by arc volcanoes along the convergent margin. However, subduction of the Cocos plate at the Middle American subduction system has resulted in an uneven distribution of magmatism/volcanism along strike. Here we construct a new three-dimensional shear-wave velocity model of the entire Middle American subduction system, using full-wave ambient noise tomography. Our model reveals significant variations of the oceanic plates along strike and down dip, in correspondence with either weakened or broken slabs after subduction. The northern and southern segments of the Cocos plate, including the Mexican flat slab subduction, are well imaged as high-velocity features, where a low-velocity mantle wedge exists and demonstrate a strong correlation with the arc volcanoes. Subduction of the central Cocos plate encounters a thick high-velocity feature beneath North America, which hinders the formation of a typical low-velocity mantle wedge and arc volcanoes. We suggest that the presence of slab tearing at both edges of the Mexican flat slab has been modifying the mantle flows, resulting in the unusual arc volcanism.
... Nonetheless, regions of pronounced low velocity (<4.52 km/s), about −2% velocity perturbation, can be observed under northeastern Mexico and offshore the northwestern US Gulf Coast. Slow shear-wave anomalies in northern Mexico have been observed in previous studies (Gaite et al., 2012(Gaite et al., , 2015Zhu et al., 2020), which identify the anomalies as fluid-induced melting in the back arc of the Rivera and Cocos subduction beneath the North American plate. The slow anomaly offshore Texas and eastern Mexico can be seen to persist to depth greater than 100 km, albeit with a decreasing amplitude. ...
... Although each of these processes is considered individually, they are not necessarily mutually exclusive. Slow seismic velocity anomalies at depths of 50-400 km in the northwestern GOM vicinity have been reported previously (Krauss & Menke, 2020;Yao & Li, 2016;Zhu et al., 2020). A deep thermal anomaly represented by slow Vs at 250-km depth as well as a shallower (50-150 km) low Vs body were imaged by teleseismic tomography centered around 92°W and 29°N (Krauss & Menke, 2020). ...
... Also, teleseismic study onshore Texas detected low Vs from 40 to 200 km below the US Gulf Coast. Zhu et al. (2020) performed full-waveform inversion for the entire Middle America and captured a slow Vs anomaly between 200 and 400-km depth, centered at 96°W 25°N in the northwestern GOM. This anomaly appears to directly overlie the subducted Rivera slab, and it might be associated with the mantle wedge seen in subduction zones under a back-arc (Wiens et al., 2008). ...
We used cross-correlation of ambient noise records from seismic stations in the US, Mexico, and Cuba to extract dispersion data of Rayleigh surface wave. Our derived 3D shear-wave velocity model of the greater Gulf of Mexico (GOM) region captures variations in the crustal and lithospheric structures across the continental margins of the US Gulf Coast and Yucatan, Mexico. The model shows a zone of reduced velocity in the mantle lithosphere underlying the extended continental margin of the northwestern GOM. We attributed this velocity reduction to extensional deformation and melt-induced weakening of the lithosphere during the Triassic continental rifting that preceded the seafloor spreading that formed the GOM. Melt extraction might have been hindered by the greater lithospheric thickness in the western region along the US Gulf Coast margin that resulted in the westward decrease of rift-related volcanism/magmatism reported from previous studies. The clear asymmetry between the US Gulf Coast and its conjugate Yucatan margin suggests extension along a shear-zone that focused more deformation on the North American plate prior to breakup. In contrast to the counterclockwise rotation of the Yucatan block during seafloor-spreading, our analyses using deformable plate models demonstrate that continental rifting occurred in a predominantly northwest-southeast direction. This change in plate motion is attributed to the development of mantle shear-zones in the western part of the rift. We estimated the depth of the lithosphere-asthenosphere boundary and determined that the extended continental and oceanic lithospheres have mostly regained their thickness since the time of breakup.
... This paper uses multiple geophysical data sets in order to sample a range of physical properties and depths from crustal levels to the lower mantle. This is particularly appropriate because the study area is one with long-lived subduction with oceanic lithosphere that can be imaged to depths greater than 1,000 km (Simmons et al., 2012;van Benthem et al., 2013;Zhu et al., 2020). The scientific value of a multidisciplinary approach to structural and tectonic studies in this region is well documented (Bernal-Olaya et al., 2015;Finger et al., 2021;Romito & Mann, 2020). ...
... The deep lithospheric and mantle structure of South America and the Caribbean has been investigated using seismic tomography (Bijwaard et al., 1998;Braszus et al., 2021;Celli et al., 2020;Cornthwaite et al., 2021;Obayashi et al., 2013;Sallarès et al., 2000;Schaeffer & Lebedev, 2013;Simmons et al., 2012;M. Sun et al., 2022;van Benthem et al., 2013;Zhu et al., 2020). A recent teleseismic P-wave tomography model (DETOX-P1) has brought the geometries of subducted slabs under South America into sharper focus through the use of regional South American data (Hosseini et al., 2020;Mohammadzaheri et al., 2021). ...
... A comparison of the DETOX-P1 tomography model (Hosseini et al., 2020;Mohammadzaheri et al., 2021) with the recent S-wave tomographic models of Zhu et al. (2020) and Celli et al. (2020) shows: (a) excellent agreement for the geometry and depth extent of the high-velocity subducting slabs and (b) poor agreement for the strength of the low-velocity features beneath the Caribbean plate. ...
The Caribbean plate is an enclosed oceanic basin whose formation and evolution are controversial. In the most commonly accepted model, the Caribbean plate is mainly composed of the Caribbean Large Igneous Province (CLIP) and the buoyant characteristic of this oceanic plateau resisted subduction and allowed an eastward migration to its present position north of South America. In this study, we integrate a broad range of geophysical and geomorphological data to define structural elements and present-day tectonics of the Caribbean plate and the surrounding region. We present a Bouguer gravity anomaly map and a new crustal thickness map that documents large areas of normal-thickness oceanic crust within the Venezuela and Colombia basins of the Caribbean plate. Selected cross sections of seismicity and P-wave anomalies from a seismic tomographic model depict the present-day geometry of subducting oceanic plates within the Caribbean region. We observe that rather than resisting subduction, as expected for the thick crust of a buoyant large igneous province, the subduction of the Caribbean plate can be traced to a depth of 600 km beneath NW South America. This, together with the crustal thickness map, implies that a significant area of the Caribbean plate, including the subducted portion, is composed of normal-thickness oceanic crust. As proposed by the Pacific origin model, the Caribbean plate likely migrated eastward from the Pacific Ocean as an oceanic plate mostly with normal-thickness crust and limited portions of the crust thickened by hot spot volcanism (CLIP).
... These inconsistent interpretations of the SWS results are not surprising considering the fact that they are path-integrated measurements offering limited vertical resolution. Compared to the SWS measurements, the depth-dependent anisotropy can be better revealed by body and surface wave inversions (e.g., Yuan & Romanowicz, 2010;Zhao et al., 2016;Zhu et al., 2020). In particular, due to the short-period nature of local and teleseismic P wave arrival-time data, P wave anisotropic inversion is theoretically capable of resolving the fine-scale anisotropic structure (e.g., Eberhart-Phillips & Henderson, 2004;Wang & Zhao, 2008). ...
We determine 3‐D isotropic and anisotropic P‐wave velocity models beneath eastern SE Asia by inverting a large number of P‐wave arrival times selected from the ISC‐EHB database. Our results reveal detailed structures of the subducting South China Sea (SCS), Negros, Molucca Sea, Philippine Sea, and Banda slabs, the previously subducted Proto‐SCS slab and remnants of other paleo slabs, showing long‐lived subductions of these oceanic slabs in eastern SE Asia. There is an obvious change in the subduction angle of the SCS slab at 18°N along the Manila trench. We suggest that the relatively low dip angle of the SCS slab to the south of 18°N was caused by subduction of an extinct mid‐ocean ridge, and a slab tear is possibly formed at 18°N. This feature is supported by the resolved fast velocity directions (FVDs) of P‐wave azimuthal anisotropy in the mantle wedge, which show that 3‐D toroidal mantle flow may develop around the southern part of the SCS slab. Trench‐normal FVDs are revealed in the deeper mantle wedge of the Sangihe subduction zone, which are associated with the deep subduction and stagnancy of the Molucca Sea slab. A nearly trench‐parallel FVD is observed beneath the Molucca Sea slab, which may be caused by trench‐parallel extension due to the retreating slab or reflect subslab mantle flow associated with the double‐sided subduction. The subducting Banda slab exhibits a curved feature, which greatly affects the flow pattern in the mantle wedge.
