The longevity of cratons usually implies that the entire cratonic lithosphere remained unchanged over billions of years, which is traditionally attributed to their intrinsically buoyant and strong lithospheric roots. By reviewing relevant studies and recent observational constraints, we show that the present cratonic roots are notably denser than the ambient mantle, with the compositional buoyancy offsetting only one-fifth of the negative thermal buoyancy. In addition, the presence of a weak mid-lithospheric discontinuity could decouple the upper and lower lithosphere upon perturbation, allowing delamination of the lower portion, while most of the delaminated lithosphere would eventually relaminate to the base of the lithosphere after sufficient warming inside the convective mantle. This process generates enduring (>100 Myr) and prominent (>1 km) surface uplifts within continents, a mechanism more compatible with data, especially those reflecting lithospheric deformation, than the model of all continents climbing up a steady region of dynamic uplift. Subsequent lithospheric cooling gradually draws the surface down to below sea level, where the lithospheric mantle density reaches a maximum upon formation of the next supercontinent. We argue that such cratonic deformation has happened repeatedly over supercontinent cycles since the Neoproterozoic and has largely shaped the properties of the present cratonic lithosphere. A few new research directions are also suggested.

大陆岩石圈的应力、应变状态对理解地球的构造演化至关重要,同时对防震减灾工作也有着重要意义.文章系统地梳理了基于不同方法和大陆岩石圈结构的相关研究,总结了目前对大陆岩石圈形变驱动力的认识,并就未来研究方向做出了展望.

Plate reconstructions reveal that two secular centers of convergence formed beneath eastern Eurasia and North America no later than 200 Ma. The cause of these convergence centers, which featured flat subduction, slab stagnation, and/or continental margin subduction, remains uncertain. Here, we propose that upper-mantle thermal inhomogeneity, particularly an anomalously cool Northern Hemispheric upper mantle, was a fundamental driver of this long-lived convergence. By considering the pattern of observed thermal inhomogeneity, our numerical models show that flow-induced asymmetrical subduction will tend to develop toward cold mantle domains, even when the subducting plate is buoyant. The models can reproduce the diverse subduction styles observed in the Northern Hemisphere by including proposed pre-subduction plate distributions and/or properties.

The western United States is one of Earth's most tectonically active regions, characterized by extensive crustal deformation through intraplate earthquakes and geodetic motion. Such intracontinental deformation is usually ascribed to plate boundary forces, lithospheric body forces, and/or viscous drag from mantle flow. However, their relative importance in driving crustal deformation remains controversial due to inconsistent assumptions on crustal and mantle structures in prior estimations. Here, we utilize a fully dynamic three-dimensional modeling framework with data assimilation to simultaneously compute lithospheric and convective mantle dynamics within the western United States. This approach allows for quantitative estimations of crustal deformation while accounting for the realistic three-dimensional lithospheric structure. Our results show the critical role of the complex lithospheric structure in governing intraplate deformation. Particularly, the interaction between the asthenospheric flow and lithospheric thickness step along the eastern boundary of the Basin and Range represents a key driving mechanism for localized crustal deformation and seismicity. The lithospheric structure controls crustal deformation in the western US. Particularly, its abrupt thickness change along the eastern boundary of the Basin and Range leads to enhanced lithosphere-asthenosphere interaction and localized earthquakes.

The driving force behind the Cenozoic India-Asia collision remains elusive. Using global-scale geodynamic modeling, we find that the continuous motion of the Indian plate is driven by a prominent upper-mantle flow pushing the thick Indian lithospheric root, originated from the northward rollover of the detached Neo-Tethyan slab and sinking slabs below East Asia. The maximum mantle drag occurs within the strong Indian lithosphere and is comparable in magnitude to that of slab pull (1013 N m−1). The thick cratonic root enhances both lithosphere-asthenosphere coupling and upper-plate compressional stress, thereby sustaining the topography of Tibetan Plateau. We show that the calculated resistant force from the India-Asia plate boundary is also close to that due to the gravitational potential energy of Tibetan Plateau. Here, we demonstrate that this mantle flow is key for the formation of the Tibetan Plateau and represents part of a hemispheric convergent flow pattern centered on central Asia. Global geodynamic modeling and force analysis reveal that the Cenozoic India-Asia collision is driven by an upper-mantle flow pushing the Indian cratonic root, a consequence of asthenosphere-lithosphere interaction within a hemispheric convergence.

The Hawaii-Emperor seamount chain showed two sub-parallel geographical and geochemical volcanic trends since ~5 Ma, the Loa and Kea trends, regarding which numerous models have been proposed that usually involved a single mantle plume sampling different compositional sources of the deep or shallow mantle. However, the eruption rate of the Hawaiian plume also dramatically increased since ~5 Ma. Moreover, this was accompanied by nearly simultaneous southward bending of the Hawaiian chain. Here, we propose a plume-plume interaction model, where the Kea trend represents the original Hawaiian plume tail, and the Loa trend represents an emerging plume head southeast of the original Hawaiian plume tail with enriched isotopic compositions. Geodynamic modeling suggests that the interaction between the emerging Loa plume head and the existing Hawaiian plume tail is responsible for the southward bending of the Hawaiian chain and the rapid growth of the eruption rate along the hotspot track. We suggest that this double-plume scenario also represents an important mechanism for the formation of other hotspot tracks in the Pacific plate, likely reflecting a dynamic reorganization of the lowermost mantle. It has implications to the formation of the LLSVP and mantle plumes in general.

Paleolatitudes of volcanic rocks reveal that prominent changes in volcanic trend of the Hawaii-Emperor hotspot chain represent meridional migration of the magma source. However, models assuming latitudinal plume migration fail to explain the observed age distribution, rock composition, and erratic paleolatitude changes of the oldest Emperor seamounts. Here we use data-assimilation models to better reproduce the Hawaii-Emperor hotspot track by systematically considering plate reconstruction, plume-lithosphere interaction, and simplified melt generation and migration. Our results show that plate drag and plume-ridge interaction are both important in explaining the observed seamount ages. These shallow dynamic processes could account for 50% of the observed paleolatitude's secular reduction and erratic variations over time, where the necessary southward migration of the Hawaiian plume root is significantly less than previously thought. We conclude that plume-lithosphere interaction represents a common mechanism in affecting hotspot track, and has important implications in understanding mantle dynamics and plate reference frames. Plume-ridge interaction modulates plume-lithosphere interaction and leads to hotspot track deviations and paleolatitude offsets in multiple hotspot chains, according to 3D data assimilation models focused on the Hawaii-Emperor hotspot track.

>1. Introduction The lithosphere is a fundamental component of Earth’s layered structure, and its stress state and deformation mechanisms are critical to understanding Earth’s tectonic evolution (Ghosh and Holt, 2012) and managing natural resources(Heidbach et al., 2018). According to the classical theory of plate tectonics, significant lithospheric deformation is expected near active plate boundaries due to the relative motion between tectonic plates.

The thermal evolution of the Earth’s interior and its dynamic effects are the focus of Earth sciences. However, the commonly adopted grid-based temperature solver is usually prone to numerical oscillations, especially in the presence of sharp thermal gradients, such as when modeling subducting slabs and rising plumes. This phenomenon prohibits the correct representation of thermal evolution and may cause incorrect implications of geodynamic processes. After examining several approaches for removing these numerical oscillations, we show that the Lagrangian method provides an ideal way to solve this problem. In this study, we propose a particle-in-cell method as a strategy for improving the solution to the energy equation and demonstrate its effectiveness in both one-dimensional and three-dimensional thermal problems, as well as in a global spherical simulation with data assimilation. We have implemented this method in the open-source finite-element code CitcomS, which features a spherical coordinate system, distributed memory parallel computing, and data assimilation algorithms.

The Hawaiian-Emperor seamount chain has shown two subparallel geographical and geochemical volcanic trends, Loa and Kea, since ∼5 Ma, for which numerous models have been proposed that usually involve a single mantle plume sampling different compositional sources of the deep or shallow mantle. However, both the dramatically increased eruption rate of the Hawaiian hotspot since ∼5 Ma and the nearly simultaneous southward bending of the Hawaiian chain remain unexplained. Here, we propose a plume-plume interaction model where the compositionally depleted Kea trend represents the original Hawaiian plume tail and the relatively enriched Loa trend represents an emerging plume head southeast of the Hawaiian plume tail. Geodynamic modeling further suggests that the interaction between the existing Hawaiian plume tail and the emerging Loa plume head is responsible for the southward bending of the Hawaiian chain. We show that the arrival of the new plume head also dramatically increases the eruption rate along the hotspot track. We suggest that this double-plume scenario may also represent an important mechanism for the formation of other hotspot tracks in the Pacific plate, likely reflecting a dynamic reorganization of the lowermost mantle.

Abstract Subduction is a fundamental process that drives plate tectonics1, 2 and supercontinent cycles3-5. The separation of a supercontinent requires the initiation of new subduction zones along its passive margins, evidenced in the appearance and increase in global continental arc volcanism6, 7 during the breakup of Pangea and Rodinia. However, the mechanism of subduction initiation (SI) at the passive margin remains elusive. Previous studies show that the mechanical resistance for SI at a mature passive margin cannot be overcome by the gravitational force of old oceanic lithosphere, even with the addition of ridge push and sediment loading8-10. Here we propose a new mechanism for passive margin SI due to delamination of the nearby cratonic lithospheric mantle (CLM), following recent findings that the CLM consists of a buoyant upper layer and a dense lower layer11-14, with the net CLM buoyancy significantly greater than that of the ambient mantle13, 14. We demonstrate that dynamic perturbations, such as plume underplating, could trigger lower CLM delamination along preexisting weak zones, while the buoyant upper CLM uplifts to damage the passive margin, ultimately leading to the formation of a new subduction zone. We further show that the developing oceanic subduction generates large extensional stress in the overriding plate, facilitating supercontinent breakup. We suggest that this new SI mechanism represents a key driving force for the periodic operation of supercontinent cycles.

The cratonic crust is the most long-lived tectonic unit on Earth. The longevity of Earth's cratonic crust has been attributed to neutrally buoyant and mechanically strong lithospheric keels. However, this is inconsistent with observed secular cratonic deformation and alteration. Here we analyse the density profile and dynamic evolution of the lithospheric mantle underlying cratons to show that cratonic lithosphere may have experienced continuous and cyclic deformation and evolution since the break-up of the Rodinia supercontinent similar to 800 million years ago. We find that the thickness of cratonic crust correlates linearly with that of the mantle lithosphere, suggesting coupled evolution. Seismic evidence for depth-dependent radial anisotropy implies that the dense lower cratonic lithosphere experienced pervasive vertical deformation consistent with delamination. Geologic data and azimuthal anisotropy further suggest repeated post-Rodinia thinning of cratonic lithosphere followed by gradual restabilization of the perturbed lower lithosphere. Geodynamic simulations support our interpretation that partial lithospheric delamination, potentially triggered by plume underplating, can generate rapid surface uplift and erosion, with subsequent lithospheric stabilization leading to gradual craton subsidence. We propose that Earth's long-lived cratons have been maintained by this cyclic deformation style since the Neoproterozoic.

Past efforts to interrogate the mantle's contribution to Earth's topography suffer from inadequate in-situ measurements of true bathymetry and the involvement of an empirical plate model whose presumed lithospheric density profile interferes with the interpretation of other mantle forces. Here, we introduce a machine learning algorithm that estimates the oceanic residual topography based solely on surface and crustal attributes, providing a more objective proxy for the topographic contribution from the mantle. Ablation studies show that seafloor age is the most important factor, while other properties help further improve the fit to bathymetry. The resulting residual topography has notably smaller amplitudes than previous estimates, indicating that more surface features can be explained by crustal properties than previously thought. This exercise, designed to allow detection of long-wavelength signals, uncovers a more prominent degree-one topographic component than the degree-two pattern, both with much smaller amplitudes than previously thought. We suggest that this result reflects a hemispheric contrast in mantle dynamics, especially the two large low shear-wave velocity provinces (LLSVPs). This inference is further strengthened by quantifying the respective topographic contributions from lithospheric isostasy and dynamic topography. We conclude that mantle convection beneath the Atlantic is more vigorous than that beneath the Pacific, likely due to their different thermal-chemical states.

Subduction of young seafloors straddling mid-ocean ridges (MOR) is an inevitable consequence of plate tectonics. Surprisingly, this process correlates globally with prolonged back-arc extension when the MOR is largely trench-parallel. We investigate the underlying mechanism by analyzing the East China Sea Basin (ECSB) whose Cenozoic tectonic history consists of three syn-rift stages with the rift center progressively migrating oceanward. Global geodynamic models satisfying the past subduction history and present-day mantle structures successfully reproduce the lithospheric stress states of the evolving ECSB. We show that segmented removal of the Mesozoic Izanagi slab due to subduction of the young seafloor initiated Paleocene rifting within the western ECSB. Detachment of the former slab facilitated a strong landward mantle wind driven by the large pressure gradient across the slab. The resulting mantle traction pushed the thickened upper plate landward while entraining the young seafloors behind to slowly subduct, a process causing long-lasting Eocene extension of the central ECSB. The waning mantle wind after 30 Ma reduced basal traction and upper plate extension. A final phase of ECSB extension since the late Miocene formed the Okinawa Trough, when the subducting plate became old enough to trigger slab retreat. A similar dynamic scenario is also predicted in other circum-Pacific margins. We conclude that this enduring back-arc extension during MOR subduction represents an important mechanism for continental evolution during the closure of major ocean basins.

The crustal stress field determines continental deformation, including intraplate seismicity and topographic undulations. However, the sources of observed crustal stress patterns remain debated, with proposed mechanisms including lateral variations in gravitational potential energy and mantle flow, the latter of which comprises plate boundary interactions and basal tractions. Here, we present a series of geodynamic models that simultaneously consider lithospheric and mantle dynamics in the same physical framework, based on which we investigate the sources of crustal stress over the conterminous U.S. The data‐oriented nature of these models allows us to systematically explore the relative contributions of different dynamic sources to the three‐dimensional crustal stress field. These models reveal that forces from the plate boundaries play a dominant role in generating the directional pattern of long‐wavelength horizontal crustal stress across the conterminous U.S. In the central U.S., especially regions of high‐topography, lithospheric density heterogeneities locally modify the crustal stress field. Similarly, mantle flow beneath the North American plate modulates crustal stress orientation in the eastern U.S., particularly in regions with thin lithosphere. Furthermore, we find that a denser‐than‐ambient lithospheric mantle beneath the central and eastern U.S. is required to match the observed continental‐scale E‐W topographic contrast.

East Asia is characterized by an east-west topographic dichotomy on the two sides of the North-South Gravity Lineament (NSGL), a feature not associated with major basement boundaries. The NSGL also marks an abrupt change in the thickness of the continental crust and the lithospheric mantle, as well as that in the associated residual topography. Both the mechanism and timing for the formation of this unique East Asian lithospheric property remain unclear. We reviewed the key tectonic records of East Asia since the early Mesozoic, with a particular focus on the plausible underlying mantle dynamics. The observation that widespread Jurassic-Early Cretaceous crustal extension occurred on both sides of the NSGL and that Cenozoic rift basins were predominantly to the east of the NSGL suggests that the seismically observed East Asian lithospheric structure came into being no earlier than the Cretaceous. Several flat-slab models have been proposed. We suggest that a combination of these models could explain the unique East Asian lithospheric evolution since the Middle Mesozoic. Further ground truth using quantitative geodynamic models with data assimilation demonstrates that a flat slab could significantly reduce the thickness of the overriding plate by dislocating and entraining the lower mantle lithosphere. Meanwhile, an advancing flat slab causes widespread upper-lithosphere compression and disappearance of the mantle wedge, implying regional-scale surface uplift (or reduced subsidence) and magmatic quiescence, respectively. We identify two episodes of Mesozoic flat slabs below East Asia, one during the Jurassic-Early Cretaceous and the other during the Late Cretaceous. The former affected the eastern half of North China and Northeast China, and the latter affected the entire region east of the NSGL from Northeast China to South China. These two flat-slab cycles largely determined the evolution of the lithosphere and topography within East Asia since the Mesozoic.