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Concealed deep beneath the oceans is a carbon conveyor belt, propelled by plate tectonics. Our understanding of its modern functioning is underpinned by direct observations, but its variability through time has been poorly quantified. Here we reconstruct oceanic plate carbon reservoirs and track the fate of subducted carbon using thermodynamic modelling. In the Mesozoic era, 250 to 66 million years ago, plate tectonic processes had a pivotal role in driving climate change. Triassic–Jurassic period cooling correlates with a reduction in solid Earth outgassing, whereas Cretaceous period greenhouse conditions can be linked to a doubling in outgassing, driven by high-speed plate tectonics. The associated ‘carbon subduction superflux’ into the subcontinental mantle may have sparked North American diamond formation. In the Cenozoic era, continental collisions slowed seafloor spreading, reducing tectonically driven outgassing, while deep-sea carbonate sediments emerged as the Earth’s largest carbon sink. Subduction and devolatilization of this reservoir beneath volcanic arcs led to a Cenozoic increase in carbon outgassing, surpassing mid-ocean ridges as the dominant source of carbon emissions 20 million years ago. An increase in solid Earth carbon emissions during Cenozoic cooling requires an increase in continental silicate weathering flux to draw down atmospheric carbon dioxide, challenging previous views and providing boundary conditions for future carbon cycle models. Oceanic plate carbon reservoirs are reconstructed and the fate of subducted carbon is tracked using thermodynamic modelling, challenging previous views and providing boundary conditions for future carbon cycle models.

About four billion years ago, Earth’s outer layer is thought to have been composed mostly of a 25- to 50-km-thick basaltic crust that differentiated to form the oldest stable continental crust. However, the tectonic processes responsible for the formation of this continental material remain controversial. Suggested explanations include convergent plate boundary processes akin to subduction operating today and a variety of relatively shallow (<50 km) non-plate-tectonic intracrustal mechanisms. Here we perform high-pressure–temperature melting experiments on an oceanic plateau analogue for the early basaltic crust and show that magmas with the composition of the early continental crust cannot form at pressures <1.4 GPa (~50 km depth). This suggests that Eoarchaean continental magmas are formed in deep (>50 km) subduction-like environments. Our results support previous Eoarchaean field evidence and analyses of igneous rocks that date to 4.0–3.6 billion years ago, which are consistent with subduction-like processes and suggest a primitive type of plate tectonics operated as long as 4 billion years ago on early Earth.Early continental crust formed at depth, implying some type of plate tectonics operating as long as 4 billion years ago, according to high-pressure and temperature melting experiments of an analogue material.

The ancient cores of continents (cratons) are underlain by mantle keels—volumes of melt-depleted, mechanically resistant, buoyant and diamondiferous mantle up to 350 kilometres thick, which have remained isolated from the hotter and denser convecting mantle for more than two billion years. Mantle keels formed only in the Early Earth (approximately 1.5 to 3.5 billion years ago in the Precambrian eon); they have no modern analogues 1 – 4 . Many keels show layering in terms of degree of melt depletion 5 – 7 . The origin of such layered lithosphere remains unknown and may be indicative of a global tectonics mode (plate rather than plume tectonics) operating in the Early Earth. Here we investigate the possible origin of mantle keels using models of oceanic subduction followed by arc-continent collision at increased mantle temperatures (150–250 degrees Celsius higher than the present-day values). We demonstrate that after Archaean plate tectonics began, the hot, ductile, positively buoyant, melt-depleted sublithospheric mantle layer located under subducting oceanic plates was unable to subduct together with the slab. The moving slab left behind craton-scale emplacements of viscous protokeel beneath adjacent continental domains. Estimates of the thickness of this sublithospheric depleted mantle show that this mechanism was efficient at the time of the major statistical maxima of cratonic lithosphere ages. Subsequent conductive cooling of these protokeels would produce mantle keels with their low modern temperatures, which are suitable for diamond formation. Precambrian subduction of oceanic plates with highly depleted mantle is thus a prerequisite for the formation of thick layered lithosphere under the continents, which permitted their longevity and survival in subsequent plate tectonic processes. Modelling reveals how thick diamondiferous continental mantle ‘keels’ were formed only at increased mantle temperatures when the melt-depleted, hot, ductile mantle located under subducting oceanic plates flowed backwards, underplating the continents.

Earth’s mantle convection, which facilitates planetary heat loss, is manifested at the surface as present-day plate tectonics 1 . When plate tectonics emerged and how it has evolved through time are two of the most fundamental and challenging questions in Earth science 1 – 4 . Metamorphic rocks—rocks that have experienced solid-state mineral transformations due to changes in pressure ( P ) and temperature ( T )—record periods of burial, heating, exhumation and cooling that reflect the tectonic environments in which they formed 5 , 6 . Changes in the global distribution of metamorphic ( P , T ) conditions in the continental crust through time might therefore reflect the secular evolution of Earth’s tectonic processes. On modern Earth, convergent plate margins are characterized by metamorphic rocks that show a bimodal distribution of apparent thermal gradients (temperature change with depth; parameterized here as metamorphic T/P ) in the form of paired metamorphic belts 5 , which is attributed to metamorphism near (low T/P ) and away from (high T/P ) subduction zones 5 , 6 . Here we show that Earth’s modern plate tectonic regime has developed gradually with secular cooling of the mantle since the Neoarchaean era, 2.5 billion years ago. We evaluate the emergence of bimodal metamorphism (as a proxy for secular change in plate tectonics) using a statistical evaluation of the distributions of metamorphic T/P through time. We find that the distribution of metamorphic T/P has gradually become wider and more distinctly bimodal from the Neoarchaean era to the present day, and the average metamorphic T/P has decreased since the Palaeoproterozoic era. Our results contrast with studies that inferred an abrupt transition in tectonic style in the Neoproterozoic era (about 0.7 billion years ago 1 , 7 , 8 ) or that suggested that modern plate tectonics has operated since the Palaeoproterozoic era (about two billion years ago 9 – 12 ) at the latest. Variability in Earth’s thermal gradients, recorded by metamorphic rocks through time, shows that Earth’s modern plate tectonics developed gradually since the Neoarchaean era, three billion years ago.

The 2024 Mw 7.5 Noto Peninsula, Japan, earthquake was initiated within the source region of intense swarm activity. To reveal the mainshock early process, we relocated the earthquake hypocenters and found that many key phenomena, including the mainshock initiation, foreshocks, swarm earthquakes, and deep aseismic slip, occurred at parts of a previously unrecognized fault in intricate fault network. This fault is subparallel (several kilometers deeper) to a known active fault, and the mainshock initiation and foreshocks occurred at the front of a 2‐year westward swarm migration. The initiation location coincides with the destination of the upward migration of a deeper earthquake cluster via several smaller faults. Fluid supply, small earthquakes, and aseismic slip on the fault likely triggered the mainshock, leading to the first major rupture at the western region, propagating further to the west and east sides, resulting in an Mw7.5 event, exceeding 100 km in length. Plain Language Summary In 2024, an earthquake of magnitude 7.5 happened on the Noto Peninsula, Japan. This earthquake started in an area where many small earthquakes occurred. To reveal how this large earthquake occurred, we precisely determined the hypocenters of the mainshock, foreshocks, aftershocks, and swarm earthquakes. We observed that the mainshock initiation, foreshocks, and some aftershocks occurred on the largest fault in the complex network. Aseismic slip also occurred near the deeper extension. This fault is not a previously known active fault, but small earthquakes migrated westward on it for over 2 years, and the mainshock rupture was initiated at the front. Directly below the mainshock initiation area, small earthquakes moved upward through several small faults. Aseismic slip propagation, fluid supply, and small earthquakes likely triggered the mainshock. The initiated mainshock rupture caused the first major slip in the western region, causing considerable uplift there and further propagating to the east and west. Despite the existence of many minor faults, many key phenomena have occurred on this previously unrecognized fault, which plays a vital role in stress release and tectonic processes in this crust. Key Points The mainshock initiation, foreshocks, and deep aseismic slip occurred on a previously unknown fault deeper than a known active fault Many swarm earthquakes that appeared to have occurred on different faults actually occurred on different parts of the same fault Mainshock rupture was initiated in a westward earthquake migration front where fluid was supplied from depth through several small faults

The Trans-Hudson orogen of North America is a circa 1,800 million year old, middle Palaeoproterozoic continental collisional belt. The orogen may represent an ancient analogue to the Himalayan orogen, which began forming 50 million years ago and remains active today. Both mountain belts exhibit similar length scales of deformation and timescales of magmatism and metamorphism. A notable divergence in this correlation has been the absence of high-pressure, low-temperature metamorphic rocks in the Trans-Hudson compared with the Himalaya. It has been debated whether this absence reflects a secular tectonic change, with the requisite cool thermal gradients precluded by warmer ambient mantle temperatures during the Palaeoproterozoic, or a lack of preservation. Here we identify eclogite rocks within the Trans-Hudson orogen. These rocks, which typically form at high pressures and cool temperatures during subduction, fill the gap in the comparative geologic record between the Trans-Hudson and Himalayan orogens. Through the application of phase equilibria modelling and in situ U–Pb monazite dating we show that the pressure–temperature conditions and relative timing of eclogite-facies metamorphism are comparable in both orogenies. The results imply that modern-day plate tectonic processes featuring deep continental subduction occurred at least 1,830 million years ago. This study highlights that the global metamorphic rock record (particularly in older terrains) is skewed by overprinting and erosion. The timing of onset of modern-style plate tectonics on Earth is unclear. Identification of eclogite rocks—typically formed during subduction—in the Trans-Hudson orogen implies modern-style tectonics may have been active 1,830 million years ago.

Plate tectonics was originally established as a kinematic theory of global tectonics, in which the Earth’s rigid outer layer, the lithosphere, consists of different size plates that move relative to each other along divergent, convergent or transform boundaries overlying the ductile asthenosphere. It comprises three elements: rigid lithosphere plates, ductile asthenosphere, and coupled movement systems. It operates through the interlinked processes of continental drift, seafloor spreading and lithospheric subduction, resulting in the generation, modification and demise of lithospheres throughout geological time. The system of lithospheric plates in horizontal and vertical movements forms the spatiotemporal linkages of matter and energy between the surface and interior of Earth, advancing the kinematic theory with a dynamic explanation. While top-down tectonics through lithospheric subduction plays a key role in the operation of plate tectonics, it is balanced for the conservation of both mass and momentum on the spherical Earth by bottom-up tectonics through asthenospheric upwelling to yield seafloor spreading after continental breakup. The gravity-driven subduction of cool lithosphere proceeds through convergence between two plates on one side, and rollback of the subducting slab makes the vacancy for upwelling of the hotter asthenosphere to form active rifting in backarc sites. Plate convergence is coupled with plate divergence between two plates along mid-ocean ridges on the other side, inducing passive rifting for seafloor spreading as a remote effect. Thus, plate tectonics is recognizable in rock records produced by tectonic processes along divergent and convergent plate margins. Although the asthenospheric upwelling along fossil suture zones may result in continental breakup, seafloor spreading is only induced by gravitational pull of the subducting oceanic slab on the remote side. Therefore, the onset and operation of plate tectonics are associated with a series of plate divergent-convergent coupling systems, and they are critically dependent on whether both construction and destruction of plates would have achieved and maintained the conservation of both mass and momentum on the spherical Earth. Plate margins experience different types of deformation, metamorphism and magmatism during their divergence, convergence or strike-slip, leaving various geological records in the interior of continental plates. After plate convergence, the thickened lithosphere along fossil suture zones in intracontinental regions may be thinned by foundering. This causes the asthenospheric upwelling to reactivate the thinned lithosphere, resulting in superimposition and modification of the geological record at previous plate margins. The operation of plate tectonics, likely since the Eoarchean, has led to heat loss at plate margins and secular cooling of the mantle, resulting in the decrease of geothermal gradients and the increase of rheological strength at convergent plate margins. Modern plate tectonics is characterized by the predominance of rigid plate margins for cold subduction, and it has prevailed through the Phanerozoic. In contrast, ancient plate tectonics, that prevailed in the Archean and Proterozoic, is dominated by relatively ductile plate margins for collisional thickening at forearc depths and then warm subduction to subarc depths. In either period, the plate divergence after lithospheric breakup must be coupled with the plate convergence in both time and space, otherwise it is impossible for the operation of plate tectonics. In this context, the creation and maintenance of plate divergent-convergent coupling systems are responsible for the onset and operation of plate tectonics, respectively. Although a global network of mobile belts is common between major plates on modern Earth, it is difficult to find its geological record on early Earth if microplates would prevail at that time. In either case, it is important to identify different types of the geological record on Earth in order to discriminate between the different styles of plate tectonics in different periods of geological history.

The structural and metamorphic evolution of the lower crust has direct effects on the lithospheric response to plate tectonic processes involved in orogeny, including subsidence of sedimentary basins, stability of deep mountain roots and extension of high-topography regions. Recent research shows that before orogeny most of the lower crust is dry, impermeable and mechanically strong 1 . During an orogenic event, the evolution of the lower crust is controlled by infiltration of fluids along localized shear or fracture zones. In the Bergen Arcs of Western Norway, shear zones initiate as faults generated by lower-crustal earthquakes. Seismic slip in the dry lower crust requires stresses at a level that can only be sustained over short timescales or local weakening mechanisms. However, normal earthquake activity in the seismogenic zone produces stress pulses that drive aftershocks in the lower crust 2 . Here we show that the volume of lower crust affected by such aftershocks is substantial and that fluid-driven associated metamorphic and structural transformations of the lower crust follow these earthquakes. This provides a ‘top-down’ effect on crustal geodynamics and connects processes operating at very different timescales. During continent collision and associated mountain building, a surprisingly large volume of the lower crust is shown to be affected by earthquake aftershocks, producing a top-down effect on crustal geodynamics.

Changes in microbialite abundance during the Archean and Paleoproterozoic have been attributed to a variety of environmental and biological factors, yet past work looking at large‐scale patterns of microbialite abundance generally assumes shallow marine deposition rather than incorporating specific settings. We compiled Archean and Paleoproterozoic microbialite occurrences and depositional environment information to assess how microbialite development and preservation changed across settings. Microbially induced sedimentary structures formed a significant part of the record, but may be undercounted as they were identified mostly in units that also contained stromatolites. While broad trends in abundance resembled previous compilations, critically, we found that more microbialites formed in tidal environments than subtidal marine. The proportion of terrestrially influenced (including tidal) microbialites peaked during periods of craton development and following the Great Oxidation Event and Huronian Glaciations. These findings highlight the importance of continental landmasses and tectonic processes in defining the distribution and preservation of early life.

Earth’s continental crust has grown and been recycled throughout geologic history along convergent plate margins. The main locus of continental crustal growth is in intra-oceanic and continental-margin arc systems in Archean time. In arc systems, oceanic lithosphere is subducted to the deeper mantle, and together with its overlying sedimentary sequence is in some cases off-scraped to form accretionary prisms. Fluids are released from the subducting slab to chemically react with the mantle wedge, forming mafic-ultramafic metasomatites, whose partial melting generates mafic melts that rise up to form arcs. In intra-oceanic arcs, they produce dominantly basaltic lavas, with a mid-crust that includes variably-developed vertically-walled intermediate plutons and higher-level dikes and sills. In continental-margin arcs, different petrogenetic processes cause assimilation and fractionation of basaltic magmas, partial melting/reworking of juvenile basaltic rocks, and mixing of mantle- and crust-derived melts, so they produce andesitic calc-alkaline melts but still have a mid-crust dominated by vertically-walled felsic plutons, which form 3-D dome-and-basin structures, akin to those in some Archean terranes such as parts of the Pilbara and Zimbabwe cratons. Notably, the continental crust of Archean times is dominated by tonalite-trondhjemite-granodiorite (TTG) plutons, similar to that of the mid-crust of these arc systems, suggesting that early continental crust may have formed largely by the amalgamation of multiple arc systems. The patterns of magmatism, in terms of petrogenesis, rock types, duration of magmatic and accretionary events, and the spatial scales of deformation and magmatism have remained essentially the same throughout geological history, demonstrating that plate tectonic processes characterized by subduction and arc magmatism have been in operation at least as long as recorded by the preserved geologic record, since the Eoarchean. However, the early Earth was dominated by accretionary orogens and oceanic arcs, that gradually grew thicker through multiple accretion events to form early continental-margin arcs by 3.5–3.2 Ga, and accretionary orogens. Slab melting and warmer metamorphism was more common in Archean arc systems due to higher mantle temperatures. These early arcs were further amalgamated into large emergent continents by ∼3.2–3.0 Ga, allowing large-scale processes such as lithospheric rifting and continental collisions, and the start of the supercontinent cycle. Further work should apply the null hypothesis, that plate tectonics explains the geologic record, to test for differences in the style of plate tectonics and magmatism through time, based on the fundamental difference in planetary heat production and the evolution of rotational dynamics of the Earth-Sun-Moon system.