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Knowledge of lithospheric structure is essential for understanding the impact of continental collision and oceanic subduction on surface tectonic configurations. Full‐waveform tomographic images reveal lateral heterogeneities and anisotropy of the lithosphere and asthenosphere in Asia. Estimating lithospheric thickness from seismic velocity reductions at depth exhibits large variations underneath different tectonic units. The thickest cratonic roots are present beneath the Sichuan, Ordos, and Tarim basins and central India. Radial anisotropy signatures of 11 representative tectonic provinces uncover the different nature and geodynamic processes of their respective past and present deformation. The large‐scale continental lithospheric deformation is characterized by low‐velocity anomalies from the Himalayan Orogen to the Baikal rift zone in central Asia, coupled with the post‐collision thickening of the crust. The horizontal low‐velocity layer of ∼100–300 km depth extent below the lithosphere points toward the existence of the asthenosphere beneath East and Southeast Asia, with heterogeneous anisotropy indicative of channel flows. Plain Language Summary The lithospheric plates, like mosaics of the Earth’s surface, are moving coherently over the weaker, convecting asthenosphere. The lithospheric structure and thickness dictated by mantle dynamics play a first‐order role in understanding the active tectonics and morphological evolution of the Asian region. Here, the latest high‐resolution full‐waveform tomographic model, SinoScope 1.0, is employed to investigate the seismic structure and dynamics of the lithosphere and asthenosphere from a seismological perspective. The lithospheric thickness of known various geological units and cratonic blocks is retrieved with large variability. The observed anisotropic signatures within the lithosphere and asthenosphere provide important constraints on the deformation state and history of different tectonic provinces. The India‐Eurasia collision primarily induced large‐scale lithospheric deformation and thickening of the crust in the west of the North‐South Gravity Lineament. The narrow low‐velocity layer below the lithosphere lies beneath East and Southeast Asia and is bounded by subduction trenches and cratonic blocks, which provides seismic evidence for the low‐viscosity asthenosphere that partially decouples plates from mantle flow beneath and allows plate tectonics to work above. The lithospheric thinning and extension, intensive magmatism, and mineralization are potentially associated with the strong interaction between the lithosphere and asthenospheric flow in the eastern Asian margin. Key Points Full‐waveform tomographic images reveal lateral heterogeneities and anisotropy in the lithosphere and asthenosphere beneath the Asian region India‐Eurasia collision induced large‐scale low‐velocity anomaly and crustal thickening spanning from the Himalayas to the Baikal rift zone Asthenosphere in East and SE Asia exhibits strong vsh, > vsv, and partially decouples lithosphere, bounded by subduction trench and cratonic keels

Controversy surrounds the fixity of both hotspots and large low shear velocity provinces (LLSVPs). Paleomagnetism, plate-circuit analyses, sediment facies, geodynamic modeling, and geochemistry suggest motion of the Hawaiian plume in Earth’s mantle during formation of the Emperor seamounts. Herein, we report new paleomagnetic data from the Hawaiian chain (Midway Atoll) that indicate the Hawaiian plume arrived at its current latitude by 28 Ma. A dramatic decrease in distance between Hawaiian-Emperor and Louisville chain seamounts between 63 and 52 Ma confirms a high rate of southward Hawaiian hotspot drift (~47 mm yr −1 ), and excludes true polar wander as a relevant factor. These findings further indicate that the Hawaiian-Emperor chain bend morphology was caused by hotspot motion, not plate motion. Rapid plume motion was likely produced by ridge-plume interaction and deeper influence of the Pacific LLSVP. When compared to plate circuit predictions, the Midway data suggest ~13 mm yr −1 of African LLSVP motion since the Oligocene. LLSVP upwellings are not fixed, but also wander as they attract plumes and are shaped by deep mantle convection. Controversy surrounds the fixity of both hotspots and large low shear velocity provinces (LLSVPs). Here, the authors present new paleomagnetic data to show that the great bend in the Hawaiian-Emperor seamount chain can be attributed to mantle plume motion and that LLSVPs are mobile.

Bends in volcanic hotspot lineaments, best represented by the large elbow in the Hawaiian-Emperor chain, were thought to directly record changes in plate motion. Several lines of geophysical inquiry now suggest that a change in the locus of upwelling in the mantle induced by mantle dynamics causes bends in hotspot tracks. Inverse modeling suggests that although deep flow near the core-mantle boundary may have played a role in the Hawaiian-Emperor bend, capture of a plume by a ridge, followed by changes in sub-Pacific mantle flow, can better explain the observations. Thus, hotspot tracks can reveal patterns of past mantle circulation.

Continental rifting is the process by which land masses separate and create new ocean basins. The emplacement of large igneous provinces (LIPs) is thought to have played a key role in (super) continental rifting; however, this relationship remains controversial due to the lack of a clearly established mechanism linking LIP emplacement to continental fragmentation. Here, we show that plume flow links LIP magmatism to continental rifting quantitatively. Our findings are further supported by the sedimentary record, as well as by the mineralogy and petrology of the rocks. This study analyzes the early Cretaceous separation of West Gondwana into South America and Africa. Prior to rifting, Jurassic hiatuses in the stratigraphic record of continental sediments from both continents indicate plume ascent and the resulting dynamic topography. Cretaceous mafic dyke swarms and sill intrusions are products of major magmatic events that coincided with continental rifting, leading to the formation of large igneous provinces in South America and Africa, including the Central Atlantic Magmatic Province, Equatorial Magmatic Province, Paraná–Etendeka, and Karoo. It has been suggested that dyke intrusions may weaken the lithosphere by reducing its mechanical strength, creating structural weaknesses that localize extensional deformation and facilitate rift initiation. The sedimentary analysis and petrological evidence from flood basalt magmas indicate that plumes may have migrated from the depths toward the surface during the Jurassic and erupted during the Cretaceous. It is thought that the resulting fast plume flow, induced by one or more mantle plumes, generated a dynamic force that, in combination with lithospheric weakening from dyke intrusion, eventually rifted the lithosphere of West Gondwana.

Australia undergoes a directional plate motion change from westward to northward motion in the early Cenozoic that is associated with Australia/Antarctica separation. At the same time, there is evidence for early Cenozoic growing dynamic topography in the western part of the continent, which we infer by mapping geological hiatus—suggesting a high-pressure source in the upper mantle to the west of Australia. Plate motion changes can be used to better constrain the torques that drive plate tectonics. Such changes in motion need adjustments in either the torques exerted at plate boundaries or basal shear stresses. Furthermore, changes in the direction plate motion are useful to pinpoint torque locations. In particular, basal shear stresses can be understood in terms of Poiseuille flow. In this context, active driving asthenosphere torques arise from pressure gradients in the asthenosphere. Thus, Poiseuille flow inherently connects both horizontal and vertical plate motions, including dynamic topography. Mantle plumes generate positive pressure gradients in the asthenosphere, which is evident from elevated dynamic topography in regions with plume activity. Here, we apply a simple Poiseuille flow model to demonstrate that the Kerguelen plume is precisely located to provide the torque to initiate the early Cenozoic directional change of Australian plate motion; these results are entirely consistent with the hiatus occurrence in the western half of the continent at that time. Our findings point out the feasibility of identifying torque sources from active upper mantle flow that can account for shifts in the direction of plate motions.

The high-resolution seismic imaging of subducted oceanic slabs 1 , 2 has become a powerful tool for reconstructing palaeogeography 3 . The images can now be interpreted quantitatively by comparison with models of the general circulation of the Earth's mantle 4 . Here we use a three-dimensional spherical computer model of mantle convection 5 , 6 to show that seismic images of the subducted Farallon plate provide strong evidence for a Mesozoic period of low-angle subduction under North America. Such a period of low-angle subduction has been invoked independently to explain Rocky Mountain uplift far inland from the plate boundary during the Laramide orogeny 7 . The computer simulations also allow us to locate the largely unknown Kula–Farallon spreading plate boundary, the location of which is important for inferring the trajectories of ‘suspect’ terrain across the Pacific basin 8 .

Computer models of mantle convection constrained by the history of Cenozoic and Mesozoic plate motions explain some deep-mantle structural heterogeneity imaged by seismic tomography, especially those related to subduction. They also reveal a 150-million-year time scale for generating thermal heterogeneity in the mantle, comparable to the record of plate motion reconstructions, so that the problem of unknown initial conditions can be overcome. The pattern of lowermost mantle structure at the coremantle boundary is controlled by subduction history, although seismic tomography reveals intense large-scale hot (low-velocity) upwelling features not explicitly predicted by the models.

Data assimilation is an approach to studying geodynamic models consistent simultaneously with observables and the governing equations of mantle flow. Such an approach is essential in mantle circulation models, where we seek to constrain an unknown initial condition some time in the past, and thus cannot hope to use first-principles convection calculations to infer the flow history of the mantle. One of the most important observables for mantle-flow history comes from models of Mesozoic and Cenozoic plate motion that provide constraints not only on the surface velocity of the mantle but also on the evolution of internal mantle-buoyancy forces due to subducted oceanic slabs. Here we present five mantle circulation models with an assimilated plate-motion history spanning the past 120 Myr, a time period for which reliable plate-motion reconstructions are available. All models agree well with upper- and mid-mantle heterogeneity imaged by seismic tomography. A simple standard model of whole-mantle convection, including a factor 40 viscosity increase from the upper to the lower mantle and predominantly internal heat generation, reveals downwellings related to Farallon and Tethys subduction. Adding 35% bottom heating from the core has the predictable effect of producing prominent high-temperature anomalies and a strong thermal boundary layer at the base of the mantle. Significantly delaying mantle flow through the transition zone either by modelling the dynamic effects of an endothermic phase reaction or by including a steep, factor 100, viscosity rise from the upper to the lower mantle results in substantial transition-zone heterogeneity, enhanced by the effects of trench migration implicit in the assimilated plate-motion history. An expected result is the failure to account for heterogeneity structure in the deepest mantle below 1500 km, which is influenced by Jurassic plate motions and thus cannot be modelled from sequential assimilation of plate motion histories limited in age to the Cretaceous. This result implies that sequential assimilation of past plate-motion models is ineffective in studying the temporal evolution of core-mantle-boundary heterogeneity, and that a method for extrapolating present-day information backwards in time is required. For short time periods (of the order of perhaps a few tens of Myr) such a method exists in the form of crude 'backward' convection calculations. For longer time periods (of the order of a mantle overturn), a rigorous approach to extrapolating information back in time exists in the form of iterative nonlinear optimization methods that carry assimilated information into the past through the use of an adjoint mantle convection model.