Water storage capacity of deep Earth mantle minerals allows storing several ocean masses. However, the amount of water delivered to the mantle through geological history remains uncertain because this depends on tectonic style. It also remains unclear how the water storage capacity of oceanic plates and the mode of delivery changed through time and how these variations controlled mantle water content and distribution. Here, we use 2D numerical modeling of subduction styles at different mantle potential temperatures (T-p) corresponding to different stages of the Earth's evolution to show two principal regimes of subduction - shallow flat subduction in the early Earth vs. deep and steep subduction in the modern Earth - that provide contrasting regimes of water recycling into the mantle. Deep and steep subduction occurs at lower mantle potential temperatures (Delta T=0-similar to 100 degrees C, T-p compared to today). During the modern regime, abundant water is transported to the mantle transition zone, where some is released from subducted slabs and retained in nominally anhydrous minerals (NAMs, wadsleyite and ringwoodite). Shallow, low angle subduction is obtained in the experiments corresponding to the hotter Precambrian mantle (Delta T=similar to 150-275 degrees C, similar to 1.5-3.0 Ga), which recycled most water into the shallow (<120 km) mantle. This regime provided cool conditions along the flattened subduction interface with limited slab melting of the mantle wedge. Shallow, flat subduction caused strong hydration of the overriding lithosphere, with water predominantly stored in hydrous minerals (e.g. serpentine, chlorite). Due to the breakdown of hydrous minerals, most of this water was easily returned to the surface and/or was stored in the continental crust. We conclude that if the secular cooling of the Earth's mantle was accompanied by changes in the subduction style from shallow to deep, then it decreased the total volume of oceanic water recycled by subduction but increased the depth of recycling and the average water content in the Mantle Transition Zone. These conclusions pertain to episodes of plate tectonics in Earth history; other modes of water delivery must be considered for single lid tectonic episodes.

Two series of numerical experiments are conducted to simulate the initiation and evolution of subduction of the Pacific Plate beneath the northern segment of the Kamchatka subduction zone. The first series modeled the self-evolving submergence at initial kinematic and physical parameters of the subduction zone. The second series additionally tested a new element of the regional subduction model: a zone of kinematic stabilization in the asthenospheric mantle to allow a shallower trajectory of slab submergence. In the first series of numerical experiments (without the stabilization zone) we studied steeply dipping subduction, which is inconsistent with the slab configuration according to available geophysical data, with the full absence of magmatism during the first 14 million years of the model time. In the second series (with the stabilization zone), we simulated the slab configuration from seismotomographic data and plotted the P–T trends (geotherms) for the slab surface and the base of the oceanic crust (Moho boundary). Volcanism was observed in the second series starting after 9 million years of the modeling time. The volcanism is mostly felsic and volcanic structures that are located at a distance of 200 km from the trench; the latter generally corresponds to the spatial arrangement of the Eastern volcanic belt relative to the trench.

The modern Earth's crust is predominantly preserved in continents, marking a significant shift from early Earth when oceanic crust was far more dominant. The growth of continental crust, composed largely of felsic rocks, began similar to 4 billion years ago in the Archean eon. The origins of these felsic rocks and thus the mechanism behind continental crust formation remains debatable, with contrasting tectonic regimes proposed for the Archean. Our new numerical modeling of intraoceanic plate convergence at elevated mantle potential temperatures (150 200 degrees C higher than present day) corresponding to the early Earth shows a shallow-dipping (flat) regime of subduction and voluminous felsic magmatism (plutonic and related volcanic) forming a thin felsic crust on top of the overriding oceanic plate. This is in strong contrast to the modern deep and steep subduction regime, which results in notably less generation of both basaltic and felsic magmas. Further modeling shows that during subsequent flat subduction of oceanic crust containing thin felsic domains, these buoyant crustal segments detach from the shallow slab portions. They rise as diapirs through the serpentinised mantle wedge, thereby forming a thick nucleus of continental crust within the oceanic crust of the upper plate. The modeled migration of felsic melts and rocks through the mantle wedge is in agreement with the presence of Precambrian sanukitoids and to some extent by Mg, Ni, and Cr enrichment in rocks from tonalite-trondhjemite-granodiorite (TTG) suites. Therefore, we conclude that shallow Precambrian subduction likely contributed notably to the formation and recycling of continental crust in Earth's early history. (c) 2025 China University of Geosciences (Beijing) and Peking University. Published by Elsevier B.V. on behalf of China University of Geosciences (Beijing). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

The epicenters of earthquakes in the Severomuysky tunnel area were found to be confined to positive anomalies of three morphometric parameters of the relief (depth of vertical dissection, asymmetry and excess of heights), contoured by values, exceeding the median or the 3rd quartile. Processing these parameters with the fuzzy logic γ-operator and the equivalent gradation method showed that both algorithms are equally informative for identifying seismically active areas. It was found that seismic events are accompanied by an increase in the horizontal velocity of movement of the IRKJ and BADG GNSS points and occur mainly at a small distance from the Earth to the Moon and the Sun, which can be explained by the increased gravitational effect of the latter on the Earth’s lithosphere. Thus, a spatial relationship between seismicity and relief and a temporal relationship with astronomical parameters and velocities of modern crustal movements was revealed.

Zonal metamorphism is widely manifested within the North Taimyr tectonic zone; it is composed mainly of rocks from the continental slope and the foot of the Kara continent passive margin. To explain the features of the observed zonal metamorphism, we have carried out numerical geodynamic modeling, which reproduces the continental collision of the Kara and Siberian continents in the Late Paleozoic. It is shown that the modeled dynamics of P–T conditions of continental crust rocks (P–T–t trends) corresponds well to the thermodynamic parameters of the observed metamorphic zonality. A geodynamic scheme has been proposed, according to which the metamorphic zonality in northwestern Taimyr was formed on the descending branch of the P–T–t metamorphism trend. This metamorphism occurred at the final stage of collision, which formed the North Taimyr tectonic zone.

In this article we examine the effects of eclogitization of slab rocks on the subduction regime under a continent. Eclogitization of rocks in high-pressure metamorphic complexes occurs only in the areas of penetration of hydrous fluid. In the absence of hydrous fluid, the kinetic delay of eclogitization preserves low-density rocks under P‒T conditions of eclogite metamorphism, delaying the weighting of a slab and reducing the efficiency of the slab-pull mechanism, which contributes to steep subduction into the deep mantle. The results of numerical petrological–thermomechanical 2D modeling of subduction under a continent in a wide range of eclogitization parameters of oceanic crustal rocks (discrete eclogitization) are presented. The effects of a lower kinetic delay of eclogitization in a water-bearing basalt layer, compared to a drier underlying gabbro layer, have been tested. Based on the results of 112 numerical experiments with 7 variants of eclogitization ranges (400–650°C for basalt and 400–1000°C for gabbro) at different potential mantle temperatures (ΔT = 0–250°C, above the modern value), and steep, flat, and transitional subduction regimes were identified. The steep subduction regime occurs under modern conditions (ΔT = 0°C) with all ranges of eclogitization. Here, it is characterized by an increase in the angle of subduction of the slab as the plate descends, and above the boundary of the mantle transition zone there is a flattening and/or tucking of the slab. Subduction is accompanied by the formation of felsic and mafic volcanics and their plutonic analogues. At elevated mantle temperatures (ΔT ≥ 150°С) and discrete eclogitization over a wide range, the flat subduction regime is observed with periodic detachments of its steeper frontal eclogitized part. The flat subduction regime is accompanied by significant serpentinization of the mantle wedge and sporadic, scarce magmatism (from mafic to felsic), which occurs at a significant distance (≥500 km) from the trench. During the transition regime, which is also achieved in models with elevated mantle temperatures, a characteristic change occurs from flat to steep subduction, resulting in a stepped shape of the slab. As the kinetic shift of eclogitization increases, flat subduction develops. An increase in the thickness of the continental lithosphere from 80 to 150 km contributes to steep subduction, while the influence of the convergence rate (5–10 cm/year) is ambiguous. Discrete eclogitization of thickened oceanic crust and depletion of lithospheric mantle in the oceanic plate are the main drivers of flat subduction. In modern conditions, their influence becomes insignificant due to the decrease in thickness of oceanic crust and degree of depletion of the oceanic mantle lithosphere. As a result, less frequent flat movement of slabs is determined by other factors.

Morphostructural analysis of the stream network of the south of the Far East has been carried out. It has been established that the latest vertical movements in the region were manifested against the background of an older, already formed and not fully eroded relief. Three stages of relief development are identified, reflecting neotectonic activity in the region: a) pre–Oligocene, characterized by a more intense uplift of the Bureinsky ridge, and less intense – the Sikhote-Alin ridge; b) Oligocene–Pliocene, characterized by the most intense vertical movements in the region during the period under review – late Eocene-Holocene; c) the Pleistocene is Holocene, during which a modern developed erosion-denudation relief was formed and no significant vertical movements occurred in amplitude. A map of the total amplitude of vertical neotectonic movements is constructed.

The newest structures of the east of the Taimyr Peninsula, which are manifested in relief, have been studied using the structural and geomorphological method; this allows us to identify the latest deformations, which have been compared with the features of the gravitational field and its transformants. A good correspondence between gravitational anomalies and magnitude of conerosional rises has been shown. It has been established that the selected blocks and their boundaries are attributed of to the specific features of the transformant field. The zones of seismicity within the Eastern Taimyr and adjacent territories tend to faults that were active in the Cenozoic, as well as to an elongated zone of contrasting values of the gravitational anomalies and their NW-striking transformants.

Morphostructural analysis of the stream network in the southern part of the Far East has been carried out. It has been established that the latest vertical movements in the region were manifested against the background of an older, partially eroded relief. Three stages of relief development are identified, reflecting neotectonic activity in the region: (a) pre–Oligocene, characterized by a more intense uplift of the Bureya Ridge, and less intense, the Sikhote-Alin Ridge; (b) Oligocene–Pliocene, characterized by the most intense vertical movements in the region during the period from the Late Eocene to the Holocene; and (c) the Pleistocene and the Holocene, during which a modern erosion-denudation relief was formed and no vertical movements of significant amplitude occurred. A map of the total amplitude of vertical neotectonic movements is constructed.

We present new results of geochronological, rock magnetic, paleomagnetic and paleointensity studies of the olivine gabbro dyke located at the northern part of the Murmansk craton, NE Fennoscandia (the Kola Peninsula). According to its geochemistry, petrographic and geochronology features, the dyke belongs to the 2.68 Ga dyke swarm, as confirmed by Sm-Nd mineral isochron. We find a significant difference in the rock magnetic and paleomagnetic characteristics of the central and marginal parts of the dyke, which is independently supported by petrography and geochemistry. It is shown that the rocks of the central part of the dyke retained not only their primary mineral composition, but also the primary component of the natural remanent magnetization. We use its direction to determine the 2.68 Ga virtual geomagnetic pole for the Murmansk craton: Slat = 68.64292° N, Slong = 37.7945° E, N = 41 specimens, Plat = –73.5°, Plong = 138.9°, dp/dm = 3.2°/3.4°, paleolat = –65.9°. We also obtain reliable estimates (17 samples) of the Earth’s magnetic field intensity at ca. 2.68 Ga: VDM value is found to be 1.85 × 1022 A m2 corresponding to the geomagnetic field several times weaker than the present-day field.

Flat (shallow) subduction is mainly proposed as an Archean-Paleoproterozoic process, contributing to the growth of continental lithosphere. However, numerical models of Precambrian subduction commonly show steep subduction. Here we investigate the effects of lithology-dependent eclogitization (minor for gabbroic lower crust, strong for basaltic upper crust) of oceanic crust during subduction. We performed 2D petrological-thermomechanical modeling of subduction at potential mantle temperatures up to 250 degrees C warmer than present, using a numerical approach that accounts for buoyancy effects from both mantle depletion and eclogitization. The modeling reveals that increases in mantle potential temperature and the related thickness of oceanic crust and depleted mantle may induce transition to the flat subduction regime at DT >= 150 degrees C but only when a delayed eclogitization of gabbroic compared to basaltic crust is taken into account. Otherwise, subduction operates in the steep slab regime. Flat Precambrian subduction models show episodic bimodal magmatism within arcs located > 400 km from the trench, caused by short-lived (1-4 Myr) subduction transients consisting of three consecutive stages: (1) twisting downward of the eclogitized slab portion, (2) subvertical descent and break-off of this twisted portion, (3) rising of the remnant non-eclogitised slab tip and continuation of flat subduction. Limited formation of TTG-series granitoids is caused by partial melting of the subducting basaltic layer but becomes less pronounced at DT = 250 degrees C. Flat subduction produces an overthickened, layered keel-like continental mantle root, with an intermediate layer of subducted oceanic crust. However, construction of longlived mantle keels by this mechanism might be limited by peeling off of the gradually eclogitizing oceanic crust and the underlaying mantle when plate convergence ends. At elevated mantle temperatures flat subduction produces voluminous hydration of the mantle wedge, forming a subcrustal serpentinite melange layer that becomes a potential source of fluids in the subsequent evolution of the overlying continental crust. CO 2023 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

In this paper, we kinematically analyze the movements of plates and blocks of the region of southeastern Turkey, where strong earthquakes occurred on February 6, 2023, based on a homogeneous database of displacement velocities of GNSS permanent monitoring stations. Along the East Anatolian fault zone from 2008 to 2018, the Arabian Plate was established to shift relative to the Anatolian Plate, which corresponds to a left shift (without a normal component) at a rate from 1 cm/yr in the eastern part to 0.8 cm/yr in the western part. Along the Chardak fault, displacements corresponding to the left shift occurred at a rate of less than 0.7 cm/year. The revealed kinematics is confirmed by focal mechanisms and cosesismic displacements of the studied earthquakes. The M 7.5 earthquake that occurred directly on the Chardak fault is not an aftershock of the M 7.8 earthquake, but is a relatively independent event. An analysis of the seismic regime shows that the stresses on the East Anatolian fault after the main M 7.8 event are relieved by the first large latitudinal fault zone (the Chardak fault). The results of our study suggest that the counterclockwise rotation of the Anatolian and Arabian plates associated with the opening of the Red Sea Rift is most likely decisive for the general kinematics of the plates in the region.

Abstract—Morphostructural analysis of the topography and the analysis of the drainage network self-similarity of the Northern Sikhote-Alin and adjacent territories has been carried out. The topography of the studied territory has an inherited nature; it was formed in several phases during the neotectonic stage. The most intense vertical movements occurred at the beginning of the neotectonic stage. The intensity of vertical movements decreased significantly in the Pleistocene, when the modern erosion-denudation landforms were formed. At the final stages of neotectonic evolution (at the end of the Pleistocene–Holocene), there was a slight activation of vertical movements that caused structural changes and the emergence of structures with an NNE stretch, which was reflected in the features of the residual relief. The areas with elevated residual relief coincide with areas of increased seismicity in the region. The proposed modification of the complex self-similarity parameter PRNS shows better correlation with the latest (youngest) movements detected by the morphostructural method. Zones of maximum PRNS values coincide with the areas of greatest relief increment, and zones of minimum PRNS coincide with areas either with the smallest relief increment, or with most significant erosion. The self-similarity characteristics obtained for the river network are mainly comparable with the manifestations of vertical tectonic movements at the final neotectonic stages.

The geological position, morphology of serpentinite bodies, limitation of ophiolite occurrences by faults, fragments of host metamorphic rocks within the Stanovaya complex of ophiolites, the character of metamorphism, the high deformation of rocks of both ophiolites and sequences at the contact zone, and mineral parageneses of secondary transformations point to the introduction of the Stanovaya ophiolites into the deeply metamorphosed Faddey Block of the Northeastern Taimyr, rather than to their obduction. The results of modeling showed that fragments of the oceanic crust introduced into the metamorphosed complexes of the continental crust during the collision may have dual origins, that is, from the primary oceanic crust, and from the newly formed crust of the back-arc basin. A detailed analysis of the chemical composition of the Stanovsky ophiolites indicates that they were formed in the suprasubduction setting of a back-arc basin, which supports the possibility of the second scenario.

The geological position, morphology of serpentinite bodies, limitation by faults, the presence of surrounding metamorphites as enclosing strata fragments within the Stanovsky ophiolite complex, the nature of metamorphism, high deformation of rocks of both ophiolites and contact zone strata, and the mineral parageneses of secondary transformations fully correspond to the signs of Stanovsky ophiolites introduction into the deeply metamorphosed Faddeevsky block strata of Northeastern Taimyr, and not their obduction. The modeling results showed that fragments of the oceanic crust introduced into the metamorphosed complexes of the continental crust during the collision can have a dual origin — from the primary oceanic crust, and from the newly formed crust of the back-arc basin. A detailed chemical composition analysis of the Stanovsky ophiolites indicates their formation in the suprasubduction setting of the back-arc basin, which justifies the possibility of the second scenario.

Morphostructural analysis of the relief and the analysis of the self-similarity characteristics of stream network of the Northern Sikhote-Alin and adjacent territories were carried out. The relief of the studied territory has an inherited character; it was formed in several stages during the neotectonic stage. The most intense vertical movements occurred at the early phases of the neotectonic stage. At Pleistocene time the intensity of vertical movements decreased significantly. At this time, the modern erosion-denudation forms of relief was formed. At the final stages of neotectonic development (at the end of the Pleistocene — Holocene), there was a slight activation of vertical movements with a changes in the structural plan and the manifestation of NNE stretched structures in the relief, which was reflected in the features of the residual relief. The boundaries of areas with increased residual relief coincide with areas of increased seismicity in the region. A modification of the complex self-similarity parameter PRNS was proposed, the use application of which allowed us to improve the correlation of this parameter with the latest (youngest) movements detected by the morphostructural method. Zones of maximum PRNS values correlate with the areas of greatest relief increment, and zones of it’s minimum correlate with areas the smallest relief increment, or areas of most significant erosion. The results of the analysis of the characteristics of self-similarity of the stream network are mainly comparable with the manifestations of vertical tectonic movements at the final stages of neotectonic development.

We present results of apatite fission-track analysis of seven intrusions located within the Permian-Triassic Siberian Traps Large Igneous Province (LIP): (1) alkaline-ultramafic central type plutons of Odikhincha, Yessey and Magan, (2) intrusions of Norilsk-1 and Kontay, (3) Padunsky sill, and (4) Kotuy dike. Additionally, we also present a set of new geochmnological data for some of studied intrusions: (a) LA-ICPMS U-Pb apatite ages of the Odikhincha pluton (266 +/- 29 Ma) and the Padunsky sill (241 +/- 12); (b) Rb-Sr ages from the Odikhincha (258.0 +/- 0.6 Ma), Magan (242.8 +/- 6.8 Ma) and Yessey (243.1 +/- 2.7 Ma) plutons; and (c) 40Ar/39Ar mica ages from the Odikhincha (264.3 +/- 3.0 Ma) and Magan (254.7 +/- 3.1 Ma) plutons. Most of these intrusions, probably with the exception of the Odikhincha, were emplaced during the most voluminous phase of the Siberian Traps magmatism ca. 252-251 Ma, but their AFT ages are distributed from 207 +/- 17 to 173 +/- 13 Ma and much younger than Late Permian to Early Triassic isotopic ages from these and other Siberian Traps LIP intrusions. Available AFT, U-Pb, Rb-Sr and 40Ar/39Ar data and time-temperature modeling has allowed us to create the first model of the post-Paleozoic tectono-thermal history of the Siberian Traps. After their emplacement ca. 251 Ma the studied rocks underwent a later phase of rapid cooling to below 120-60 degrees C during the time interval similar to 207-173 Ma and have remained near the surface until present. We propose this later cooling event is linked to exhumation associated with coeval Late Triassic-Early Jurassic large-scale uplift of the Siberian platform caused by collisional processes at its periphery. Our new results also indicate that at least a 1-2 km thickness of Siberian Traps lavas have been removed by erosion in the north of the Siberian platform since eruption, implying the total volume of the Permian-Triassic lavas was much greater than that currently preserved today.

Available data suggest that the breakup of the Neoarchean Kenorland supercontinent at 2.5-2.4 Ga was likely triggered by a large mantle plume upwelling that caused significant magmatism. Here, we present 2D high-resolution magmatic-thermomechanical numerical models of extension of the continental crust underplated by a hot mantle plume material. Using this model, it is demonstrated that mantle plume underplating generates a large amount of mafic melt by decompression melting. This melt penetrates into the extending continental crust along normal faults thereby forming multiple generations of mafic dyke-like intrusions along normal faults. In case of extension velocity of 0.2-1 cm/yr, lower crustal heating and hot mafic melt emplacement may cause partial melting of the continental crust that can generate significant volume of felsic melts. This in turn triggers emplacement of felsic intrusions that temporarily and spatially associate with the mafic dyke-like intrusions. The modeling results agree well with geological data from the Karelian Craton and provide possible explanation for the observed association of Paleoproterozoic mafic dykes and felsic intrusions which formed in a relatively short time interval (up to 20 Myrs) in the early stages of the supercontinent breakup.