The serpentinized mantle in subduction zones plays a key role in transporting water into Earth’s interior and influencing subduction dynamics. However, estimates of serpentinization vary significantly across and within different trenches. Using 2-D thermomechanical numerical models, we investigate how variations in subduction angle, thickness, and serpentinization degree influence subduction processes in the southern and central Mariana Trench. Our models reveal three distinct subduction regimes: stable subduction, crustal exhumation, and crustal accretion, which depend on the thickness and degree of serpentinization. Stable subduction occurs in the southern and central Mariana regions where the serpentinized mantle is <13 km and 14 km thick, respectively. In the southern Mariana Trench, buoyancy-driven crustal exhumation occurs with a serpentinized mantle thickness of 14−17 km, consistent with the presence of high-pressure metamorphic rocks in the forearc. Crustal accretion, while theoretically possible, is not observed in the Mariana Trench, suggesting the serpentinized mantle is either thin or only partially serpentinized (e.g., ≤4.4 wt% at a thickness of 21 km). By integrating our model predictions with geophysical observations, we estimate the maximum thickness of fully serpentinized mantle at 17 km in the southern Mariana and 13 km in the central Mariana Trench, implying up to 30% higher water influx in the southern region. These findings refine constraints on water input variations along the Mariana Trench and highlight the significance of serpentinization in interpreting geophysical anomalies in subduction zones.

Abstract The formation of wide, magma‐starved continent–ocean transition (COT) zones remains incompletely understood. We use 2‐D thermo‐mechanical numerical experiments, coupling hydrous mantle melting with parameterized crustal accretion, to explore controls on magmatic lag: the delay between continental crustal break‐up and steady oceanic crustal accretion. Modeling results show that: (a) buoyant rise of subcontinental lithosphere up and toward the rift zone, which inhibits asthenosphere upwelling and decompression melting; (b) a weak mid‐lithospheric discontinuity lengthens magmatic lag by ∼15 Myr and widens the COT by >200 km; (c) the lateral distance over thick, depleted mantle influences rift magmatism is governed by lithospheric density and rheology; and (d) magmatic lag scales linearly with the density contrast between lithospheric mantle and asthenospheric mantle. Model outputs match observed COT widths from the central South Atlantic and conjugate Australia–Antarctica margins, linking inherited lithospheric mantle heterogeneity to melt starvation, mantle exhumation, and rifted‐margin architecture.

Abstract Evolutionary models for the Proterozoic Aravalli–Delhi fold belt (ADFB) in northwestern India are debatable due to the nonreflective crust resulting in a partially resolved crustal structure, poor imaging of the Moho, and ambiguity in the subduction polarity. Receiver function (RF) analysis was done using ≈5000 RFs from 30 broadband stations spaced at intervals of ≈10 to 12 km along a 250-km-long northwest–southeast traverse across the ADFB. High-resolution common conversion point imaging was performed using the VP/VS ratios (κ) and the 1D shear-wave velocity (VS) models estimated from H−κ stacking and neighbourhood inversion, respectively. The geometry and continuity of the Moho and the intracrustal layers beneath the ADFB are imaged with better resolution than the earlier studies. The Delhi Fold Belt (DFB), located between the Marwar basin (MB) and the Banded Gneissic Complex (BGC), is characterized by an anomalously thick (≈52 km) crust, a southeast-dipping Moho, a domal midcrustal interface, and a mafic lower crust with VS≥4 km/s. In contrast, MB is underlain by a thin (≈38 km) felsic crust, and BGC is predominantly characterized by a felsic crust with thickness increasing from ≈38 to ≈45 km toward DFB. The feasible mechanisms of crustal thickening, such as magmatic underplating, relamination, and crustal shortening, are examined within the framework of ensialic and plate tectonic models. The convergence between the Marwar and Aravalli cratons led to the subduction of the intervening oceanic crust, possibly comprising island arcs, which were detached, melted, and relaminated to the base of the crust, followed by crustal accretion and shortening due to collisional tectonics. The mafic residue of the rift-related magma and fractionated melts forms a high-velocity lower crust, resulting in a rheologically strong, thick crust beneath DFB.

Abstract The J magnetic anomaly in the Central Atlantic has 10 times larger amplitude than surrounding seafloor‐spreading magnetic lineations and is often associated with thick oceanic crust formed by excess magma. The anomaly has also been identified in the southern North Atlantic, where it has been linked to the onset of seafloor spreading, challenging traditional 2D models of lithospheric break‐up offshore Iberia. These findings underscore the importance of constraining the crustal structure along the J anomaly to fully understand its genetic processes and geodynamic significance. Yet, the crustal structure in the Central Atlantic, where the anomaly is strongest, remains poorly defined by low‐resolution legacy seismic data. We present wide‐angle and multichannel seismic data from the 2022 ATLANTIS survey across the J anomaly at ∼31°N in the Central Atlantic. We use 2D seismic tomography to invert for P‐wave ( Vp ) and S‐wave ( Vs ) velocities. Results reveal significant lateral variations in igneous basement thickness and seismic velocities, contradicting the idea of uniformly thick crust. The peak of the anomaly is not aligned with the thickest segment (10 km) but with a region where oceanic layer 3 exhibits the fastest Vp and Vs . Variations in basement thickness are accompanied by lateral differences in Vp / Vs , reflecting changes in composition and/or basement fracturing. These findings suggest diverse crustal accretion processes, influenced by a fertile mantle source and short‐term mantle temperature differences during the formation of the J anomaly.

Abstract New helium isotope data for basalt glasses from the Gulf of Tadjoura and Gulf of Aden reveal a mantle plume signal that has 3 He/ 4 He up to 17 R A . In the Gulf of Aden, plume helium is detectable ∼380 km from the Afar triple junction, up to the Shukra El Sheik Fracture Zone along the West Sheba Ridge, but not beyond. The trace of the fracture zone onto the coastal margins also marks the eastward extent of volcanic terranes attributed to Afar plume influence on the ocean‐continent transition. The lack of elevated 3 He/ 4 He beyond this point and the history of westward propagation of spreading in the Gulf of Aden toward the triple junction indicate that the Afar plume has a limited influence on modern‐day crustal accretion along most of the Sheba Ridge. Eastward of the Afar plume influence, basalts show uniform 3 He/ 4 He = 8.08 ± 0.20 R A (1 σ , n = 22) along >1,100 km of the ridge axis. This is among the most uniform sections of the global mid‐ocean ridge system for helium isotopes. The uniformity likely results from enhanced homogenization by small‐scale convection in the upper mantle beneath ultra‐slow spreading ridges. Regional He–Pb–Nd–Sr isotope variations follow a pattern similar to that for ocean island basalts, showing a decrease in 3 He/ 4 He as the proportion of recycled material increases in the mantle source region. Source contributions include the Afar mantle plume, shallow asthenosphere, Pan‐African lithosphere, and a sporadic HIMU component that originates either from the continental lithosphere or from within the Afar plume.

The metallogenic process of gold deposits is typically characterized by multi-stage mineralization and complex tectonic evolution. Precise determination of metallogenic age is thus critical yet challenging for establishing ore-forming models and tectonic evolutionary frameworks. The Koka gold deposit in Eritrea represents the largest gold discovery to date in the area, though its metallogenic age and tectonic evolution remain debated. This study employs in situ micro-analysis techniques to investigate major/trace elements and U-Pb geochronology of hydrothermal monazite coexisting with gold mineralization, providing new constraints on the metallogenic timeline and tectonic setting. Petrographic observations reveal well-crystallized monazite with structural associations to pyrite and native gold, indicating near-contemporaneous formation. Trace element geochemistry shows peak formation temperatures of 270–340 °C for monazite, consistent with fluid inclusion data. Genetic diagrams confirm a hydrothermal origin, enabling metallogenic age determination. Monazite Tera–Wasserburg lower intercept ages and weighted mean 208Pb/233Th ages yield 586 ± 8.7 Ma and 589 ± 2.3 Ma, respectively, overlapping error ranges with published sericite 40Ar/39Ar ages. This confirms Ediacaran gold mineralization, unrelated to the Koka granite (851 ± 2 Ma). Statistical analysis of reliable age data reveals a three-stage tectonic evolution model: (1) 1000–875 Ma, Rodinia supercontinental rifting, with depleted mantle-derived mafic oceanic crust formation and Mozambique Ocean spreading; (2) 875–630 Ma, subduction-driven crustal accretion and Koka granite emplacement; and (3) 630–570 Ma, post-collision crustal/lithospheric remelting, with mixed metamorphic–magmatic fluids and meteoric water input driving gold precipitation.

Summary Transform faults are one of the major tectonic plate boundaries offsetting the global mid-oceanic ridge system. The topographic features within these transform faults provide crucial evidence for tectono-magmatic processes and crustal accretion in transform fault zones. These interesting features include median ridges, which are major bathymetric anomalies found within both slow-slipping and fast-slipping transform faults, often associated with exposures of ultramafic rocks on the seafloor. To explain the origin of median ridges, previous studies have invoked multiple processes such as serpentinite diapirism, thermal uplift at ridge-transform intersections, or transpressive uplift induced by global plate reorganization, without any knowledge of the seismic structure. Here, we present results from 2D travel time tomography of downward-continued multi-channel seismic data along and across an ∼80 km long median ridge that lies within the eastern end of the slow-slipping (∼3.4 cm/yr) Chain transform fault in the equatorial Atlantic Ocean. The data were acquired during the 2018 ILAB-SPARC survey using a 6-km long streamer. Our high-resolution P-wave velocity model of the median ridge shows distinct high and low velocities ranging from 2.5 to 5 km/s within 500 m below the seafloor, on either side of the presently active strike-slip fault trace that cuts through the ridge. The low velocity on the eastern side of the ridge could be due to the presence of highly fractured basalt (with porosity in the range of 28 to 36 per cent) due to transform fault motion, whereas the high velocity on the western flank could be due to the presence of gabbro or highly serpentinised peridotite. The basaltic origin of the median ridge is supported by the observation of a seismic triplication event, which we call the T-event. The depth at which the T-event maps is shallow (200–500 m below seafloor) in high-velocity regions and deeper (600–1400 m) in low-velocity regions. We also find that the currently active strike-slip fault has been active since at least 0.26 Ma and has sliced the ridge. We image low-velocity pockets at the northern and southern limits of the median ridge that could represent the expression of the currently less active strike-slip faults.

Intraplate magmatic processes associated with crustal accretion at the West Philippine Basin, Western Pacific

Abstract Understanding the relationship between surface and deep geological processes in tectonically active settings is crucial for unraveling the factors controlling landscape evolution and topographic growth. Here, we present the first basin‐averaged 10Be‐derived denudation rates for the Albanides, a subduction orogen in the Central Mediterranean. By integrating these data with topographic and fluvial analyses, we quantify Quaternary uplift rates and better constrain the spatial and temporal distribution of tectonic deformation, linking the existing long‐term thermochronological data with short‐term river incision rates. Denudation rates from nine basins range from 0.18 to 1.28 mm/yr, showing a general increase from the external compressional domain to the internal extensional domain. The denudation rates, calculated in catchments assumed to be in dynamic equilibrium and hence interpreted as proxies for uplift, reveal a consistent spatial pattern of tectonic uplift that aligns with active tectonic structures. Higher rates are observed in basins located at the hanging wall of thrust faults or at the footwall of normal faults. The imprint of active tectonics in the landscape is indicated by evidence of river network reorganisation and in the topography. A broad, across‐strike increase in mean elevation, combined with local topographic variations along faults, suggests tectonic control on relief, modulated by lithological contrasts. We considered this uplift signal to be potentially controlled by a combination of both deep (e.g., crustal accretion) and shallow (i.e., surface faulting) processes. The former appears to drive the regional topographic pattern, while the latter contributes to localized uplift signals, enhanced denudation rates, and drainage reorganisation.

Asymmetric oceanic crustal accretion and mantle serpentinization in the southwestern propagator tip of the South China Sea basin

Paleoproterozoic continental crust accretion on the northern margin of the North China Craton: Evidence from the Shangyi Complex at the eastern segment of the Khondalite Belt

Crustal accretion, polygenetic reworking, and extensive porphyry-skarn Cu-Au/Fe and W-Mo mineralization: A case study from the central Yangtze River ore belt and adjacent areas, eastern China

The transition from the Archean to Proterozoic marks a critical period in Earth’s tectonic history, where primary crustal formation mechanisms may have shifted from vertical-accretion mantle plume tectonics to horizontal-accretion modern-style plate tectonics. Seismological evidence suggests that this regime shift might have left imprints in the crust of stable regions. However, due to sparse spatial and temporal sampling, there is no global consensus on whether seismic observations can infer the secular evolution of crustal characteristics. In this study, we utilized a dense seismic array deployed in the Capricorn Orogen of the West Australian Craton. By analyzing teleseismic receiver functions, we characterized the crustal VP/VS ratio and interface features across approximately two billion years of Archean to Proterozoic craton crust and correlated these observations with the two-stage Nd age model of surficial rocks. Our results indicate that during the Mesoarchean to Paleoproterozoic, crustal thickness in the Capricorn Orogen gradually increased. The changes of VP/VS ratio suggest a crustal evolution from felsic to more intermediate compositions, and the Moho gradient evolves from sharp to gradational. Significant crustal thickening and mafic compositions were observed along major block boundaries, accompanied by weak Moho amplitudes, and asymmetrically dipping Moho, spatially correlating with the Ophthalmia Orogeny (∼2.2 Ga) and the Glenburgh Orogeny (∼2.0 Ga). We propose that these changes in the crustal characteristic initially originated during these two collisional orogenies and were further modified by post-collision thermal and deformational events. Similar features are evident in seismic observations across many Precambrian subduction zones. Thus, we infer that around 2.2 to 2.0 billion years ago, primary crustal formation mechanisms in the West Australian Craton had transitioned to horizontal accretion modern plate tectonics. This study reveals the geometrical characteristics of Neoarchean to Paleoproterozoic subduction, providing new deep constraints for understanding the Archean-Proterozoic crustal accretion and geodynamic regime transitions.

Abstract We summarize evidence suggesting that magmatic accreted crust (subaerially accreted crust and submarine accreted oceanic crust) underlies a much larger portion of the Gulf of Mexico basin than has been appreciated previously. This conclusion suggests that traditional models of the Jurassic tectonic development of the basin, with wide areas of thinned continental crust underlying the salt basins, require significant modification. Using an updated compilation of long-offset, deep-penetrating offshore and reprocessed onshore seismic reflection profiles, we produced a new plate kinematic interpretation for the Gulf of Mexico linked to a process-based understanding of key tectonic events, their timing, and the distribution and structure of crustal types and pre-salt sediments observed across the Gulf of Mexico. The near-onshore and offshore Gulf of Mexico region is interpreted to be underlain by accreted magmatic crust formed during two phases of seafloor spreading: (1) an older rim of subaerial seafloor spreading marked by seaward-dipping reflectors that grade laterally into thin, accreted crust of an enigmatic nature overlain by an undeformed pre-salt sedimentary succession, and (2) younger production of more normal submarine Penrose crust. Continental breakup was diachronous, initiating at 200–190 Ma and becoming younger to the east, and marked by easterly trending extensional propagators preserved as basin systems along the western margin of Florida: the Mississippi Salt Basin, Apalachicola Basin, and Tampa Embayment. These propagators formed successively from north to south and west to east as the Gulf of Mexico spreading system adjusted to Yucatan rotation, before the spreading axis shifted southward into the Florida Straits. Phase 1 breakup initiated north of the present coast along the Houston magnetic anomaly, with little local evidence for upper-crustal faulting. Any crustal thinning there would thus have been a consequence of lower-crustal, depth-dependent continental extension. Regionally, unextended continental crust may be evidence of exploitation of preexisting Alleghanian-Ouachita weaknesses, of which the western continuation of the Suwannee shear zone is a prime candidate. Between phase 1 breakup (200–190 Ma) and 169 Ma, Yucatan migrated southeastward with South America (Gondwana) and rotated ~15° counterclockwise. This gradual southward shift of Gulf of Mexico accretion may have resulted from the region's extension axis encountering rheological strength barriers related to the Central Atlantic and proto–Caribbean Ocean margins. Each successive line of breakup was characterized by an initial phase of subaerial extrusions and development of seaward-dipping reflectors. Evidence suggests that these extension systems in the eastern Gulf of Mexico occurred in a widening and propagating basin network below global sea level, where continental sediments were deposited in subaerial and/or lacustrine environments and ultimately capped by evaporites. In phase 2, between 169 Ma and 140 Ma, Yucatan rotated an additional ~52° counterclockwise. Evaporites started forming in Bajocian (169 Ma) time during transient connection(s) to the global ocean. Fully marine conditions were established in Callovian (164 Ma) time as rotation continued, resulting in submarine accretion of Penrose crust. A major implication of this work is confirmation that prolific hydrocarbon systems can develop on “oceanic” (accreted) crust if ambient depositional environments are favorable.

Formation of new lithosphere at mid-oceanic ridges occurs through magmatic crustal accretion and cooling of the asthenosphere, and is essentially controlled by the spreading-rate, ridge segmentation, and eventual arrival of deeply-sourced hot mantle plumes. Its dependence on long-term inheritance is supposedly weak, except in cases where ridge segmentation is preconditioned by the reactivation of continental weak zones during the rifting phase. Here, we provide the first evidence that pre-rift lithospheric thickness variations constitute another forcing that may transmit influence from past Wilson cycles beyond the stage of continental break-up. This long-term control involves differential redistribution of heat/melt sources along young laterally-confined plume-assisted rifts. This is demonstrated here in the case of the Red Sea from the correlation between on-axis volcano-tectonic patterns, distribution of onshore volcanism, and lithospheric thickness variations of the rifted margins.

The Alto Moxotó Terrane is one of the best-preserved Paleoproterozoic crustal segments of the Borborema Province and shows a close correlation with basement domains of the Central African Fold Belt. Here, we review geochemical and isotopic data for Neoarchean and Paleoproterozoic rocks within the terrane and their implications for the crustal evolution of western Gondwana. The lithospheric framework of the terrane consists of three main tectonomagmatic stages: (1) Neoarchean ( c. 2.6 Ga) crustal accretion with tonalite, trondhjemite and granodiorite juvenile injections, consisting of calcic, magnesian and meta- to peraluminous magmas derived from a basaltic oceanic crust that probably experienced high-pressure conditions; (2) Rhyacian–Orosirian ( c. 2.1–1.9 Ga) tholeiitic mafic–ultramafic and calc-alkaline series Cordilleran-related granitic and gneissic rocks; (3) Statherian–Calymmian within-plate magmatism ( c. 1.6 Ga), with granitic rocks that correspond to A-type ferroan magmas, generated via partial melting of a continental source. The presence of older events within the Alto Moxotó Terrane allows correlation with basement domains within the Borborema Province and other Neoproterozoic orogens of Gondwana. These correlations strengthen the role of the province's Paleoproterozoic domains in palaeogeographical reconstructions of the Nuna–Columbia supercontinents.

Abstract As the most recent collisional event prior to the early Cenozoic India‐Asia collision, the suturing of the Lhasa‐Qiangtang terranes resulted in crustal accretion and the formation of lithospheric structures that greatly influenced subsequent Cenozoic rock uplift in central Tibet. The discovery of several microcontinents within the Bangong‐Nujiang suture zone between the Lhasa and Qiangtang terranes potentially implies multiple suturing stages, however, how and when the suturing of these terranes occurred are highly disputed. Here, we present a newly discovered latest Jurassic to Early Cretaceous deep‐marine gravity‐fan succession that is over 660 m thick in the Jienu Mountain region, south to the Cenozoic Lunpola basin. By employing multi‐proxy, single‐grain provenance analysis and forward modeling of sediment mixtures, we find the detritus was deposited in a syn‐collisional trench and was sourced from the Dongkaco microcontinent, the obducted ophiolite—subduction complex, the accreted seamounts, and the volcanic arc rocks. We interpret that this trench deposition occurred due to the latest Jurassic to Early Cretaceous collision of the Lhasa terrane beneath the Dongkaco microcontinent and other accreted components. The sutured Dongkaco microcontinent forms the basement to the Lunpola basin and is inferred not present beneath the narrower Nima, Gaize, and Awenco basins along strike to the west where these basins are either narrower or exhibit abrupt facies changes with time. This study highlights the importance of Mesozoic tectonic inheritance on subsequent Cenozoic uplift of the Tibetan Plateau.

Abstract The Lucky Strike segment at the Mid‐Atlantic ridge, characterized by a well‐defined median valley with a central volcano, is an archetypical slow‐spreading ridge segment and hence an ideal site for studying magmatic and tectonic processes at slow‐spreading ridges. Here we present fine‐scale velocity models of this segment, by applying full waveform inversion to wide‐angle seismic data, that allows characterization of crustal accretion processes along the entire segment. Along ridge axis, the crust thins from ∼8.4 km at the center of the segment to ∼3.7–4.1 km at the segment ends. This large variation in crustal thickness is mainly accommodated by lower crustal thinning toward the segment ends. The ratio of the lower/upper crust thickness varies from 2.2 at the segment center to 0.1 at the segment ends, so upper crust at segment ends accounts for ∼90% of the crustal thickness, suggesting that the lateral dyking is the primary crustal accretion mechanism. The reduction of lower crustal velocity at the segment center indicates the presence there of melt within the lower crust, which is the source of melt delivery for dyke propagation. The upper crustal velocity gradually decreases from the segment center to segment ends, consistent with an increase in faulting and the presence of more evolved magma toward the segment ends. These observations demonstrate the presence of focused magma supply to the segment center. Off‐axis, the upper crustal thickness shows little variation over ∼30 km on both flanks, suggesting the current magmatic accretion mode could have been active for 3 Myr.

The West Junggar area in the southwestern part of the Central Asian Orogenic Belt (CAOB), is one of the largest areas of growth of the Phanerozoic crust in the world that has experienced intense Late Paleozoic magmatic activity, where crust-mantle interaction is significant. The issue of crustal growth has long been regarded as one of the most fundamental in earth sciences. In light of the challenges posed by the composition of deep materials and the Late Paleozoic crustal growth in the West Junggar area, there is a continued need to systematically determine the spatial distribution characteristics of deep materials in the crust, analysis the growth pattern and growth volume of the crust, and enhance the Late Paleozoic tectonic evolution of the region. Focusing on granite type Sr-Nd-Pb-Hf isotopic mapping, this study found that the West Junggar area has the isotopic characteristics of high positive εHf (t) and εNd (t), low (87 Sr/86 Sr)i, and young crustal mode age, there is almost no old crystalline basement in the deep crust. During the Late Paleozoic, about 85% of West Junggar had 75%–95% crustal growth, dominated by lateral crustal growth and material recirculation; about 15% of the area (connected to the Jietebudiao area) had 50%–75% crustal growth, dominated by vertical crustal growth. The West Junggar area mainly experienced four orogenic stages in the Late Paleozoic. In the Early Carboniferous period (360–320 Ma), there was significant intra-oceanic subduction, involving a substantial amount of juvenile material in lateral crustal accretion. The Late Carboniferous-Early Permian period (320–294 Ma) is the post-orogenic extension stage, during which a massive amount of juvenile mantle source was added. This resulted in the most intense magmatism and crustal growth, which could have the growth of the crust potentially more than 75%. In the Early Permian period (294–272 Ma), there was an intracontinental evolution stage and a decrease in the participation of juvenile material. During the Early Permian-Early Triassic period (272–250 Ma), magmatic activity decreased significantly, where the southwestern region experienced high-temperature, low-pressure, crustal thinning extension. Despite this, the crust received juvenile material, and plutonic magma intrusion occurred.

The rare earth elements Sm and Nd significantly address fundamental questions about crustal growth, such as its spatiotemporal evolution and the interplay between orogenesis and crustal accretion. Their relative immobility during high-grade metamorphism makes the Sm-Nd isotopic system crucial for inferring crustal formation times. Historically, data have been disseminated sporadically in the scientific literature due to complicated and costly sampling procedures, resulting in a fragmented knowledge base. However, the scattering of critical geoscience data across multiple publications poses significant challenges regarding human capital and time. In response, we present an automated tabular extraction method for harvesting tabular geoscience data. We collect 10,624 Sm-Nd data entries from 9,138 tables in over 20,000 geoscience publications using this method. We manually selected 2,118 data points from it to supplement the previously constructed global Sm-Nd dataset, increasing its sample count by over 20%. Our automatic data collection methodology enhances the efficiency of data acquisition processes spanning various scientific domains.