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The formation and preservation of cratons—the oldest parts of the continents, comprising over 60 per cent of the continental landmass—remains an enduring problem. Key to craton development is how and when the thick strong mantle roots that underlie these regions formed and evolved. Peridotite melting residues forming cratonic lithospheric roots mostly originated via relatively low-pressure melting and were subsequently transported to greater depth by thickening produced by lateral accretion and compression. The longest-lived cratons were assembled during Mesoarchean and Palaeoproterozoic times, creating the stable mantle roots 150 to 250 kilometres thick that are critical to preserving Earth’s early continents and central to defining the cratons, although we extend the definition of cratons to include extensive regions of long-stable Mesoproterozoic crust also underpinned by thick lithospheric roots. The production of widespread thick and strong lithosphere via the process of orogenic thickening, possibly in several cycles, was fundamental to the eventual emergence of extensive continental landmasses—the cratons. Cratons are the oldest parts of the Earth’s continents; this Review concludes that the production of widespread, thick and strong lithosphere via the process of orogenic thickening was fundamental to the eventual emergence of extensive continental landmasses.

The evolution of past global ice sheets is highly uncertain. One example is the missing ice problem during the Last Glacial Maximum (LGM, 26 000-19 000 years before present) – an apparent 8-28 m discrepancy between far-field sea level indicators and modelled sea level from ice sheet reconstructions. In the absence of ice sheet reconstructions, researchers often use marine δ 18 O proxy records to infer ice volume prior to the LGM. We present a global ice sheet reconstruction for the past 80 000 years, called PaleoMIST 1.0, constructed independently of far-field sea level and δ 18 O proxy records. Our reconstruction is compatible with LGM far-field sea-level records without requiring extra ice volume, thus solving the missing ice problem. However, for Marine Isotope Stage 3 (57 000-29 000 years before present) - a pre-LGM period - our reconstruction does not match proxy-based sea level reconstructions, indicating the relationship between marine δ 18 O and sea level may be more complex than assumed. The configuration of past ice sheets, and therefore sea level, is highly uncertain. Here, the authors provide a global reconstruction of ice sheets for the past 80,000 years that allows to test proxy based sea level reconstructions and helps to reconcile disagreements with sea level changes inferred from models.

New geochronological and geochemical data on magmatic activity from the India-Asia collision zone enables recognition of a distinct magmatic flare-up event that we ascribe to slab breakoff. This tie-point in the collisional record can be used to back-date to the time of initial impingement of the Indian continent with the Asian margin. Continental arc magmatism in southern Tibet during 80–40 Ma migrated from south to north and then back to south with significant mantle input at 70–43 Ma. A pronounced flare up in magmatic intensity (including ignimbrite and mafic rock) at ca. 52–51 Ma corresponds to a sudden decrease in the India-Asia convergence rate. Geological and geochemical data are consistent with mantle input controlled by slab rollback from ca. 70 Ma and slab breakoff at ca. 53 Ma. We propose that the slowdown of the Indian plate at ca. 51 Ma is largely the consequence of slab breakoff of the subducting Neo-Tethyan oceanic lithosphere, rather than the onset of the India-Asia collision as traditionally interpreted, implying that the initial India-Asia collision commenced earlier, likely at ca. 55 Ma.

Fault-zone fluids control effective normal stress and fault strength. While most earthquake models assume a fixed pore fluid pressure distribution, geologists have documented fault valving behavior, that is, cyclic changes in pressure and unsteady fluid migration along faults. Here we quantify fault valving through 2-D antiplane shear simulations of earthquake sequences on a strike-slip fault with rate-and-state friction, upward Darcy flow along a permeable fault zone, and permeability evolution. Fluid overpressure develops during the interseismic period, when healing/sealing reduces fault permeability, and is released after earthquakes enhance permeability. Coupling between fluid flow, permeability and pressure evolution, and slip produces fluid-driven aseismic slip near the base of the seismogenic zone and earthquake swarms within the seismogenic zone, as ascending fluids pressurize and weaken the fault. This model might explain observations of late interseismic fault unlocking, slow slip and creep transients, swarm seismicity, and rapid pressure/stress transmission in induced seismicity sequences. Coupling between fault zone fluid flow, permeability evolution, and elastic stress transfer produces fault valving and fluid-driven aseismic slip and pore pressure pulses. This model might explain late interseismic fault unlocking, slow slip, and rapid pressure transmission in induced seismicity.

Convergence between the Indian and Asian plates has reshaped large parts of Asia, changing regional climate and biodiversity, yet geodynamic models fundamentally diverge on how convergence was accommodated since the India–Asia collision. Here we report palaeomagnetic data from the Burma Terrane, which is at the eastern edge of the collision zone and is famous for its Cretaceous amber biota, to better determine the evolution of the India–Asia collision. The Burma Terrane was part of a Trans-Tethyan island arc and stood at a near-equatorial southern latitude at ~95 Ma, suggesting island endemism for the Burmese amber biota. The Burma Terrane underwent significant clockwise rotation between ~80 and 50 Ma, causing its subduction margin to become hyper-oblique. Subsequently, it was translated northward on the Indian Plate by an exceptional distance of at least 2,000 km along a dextral strike-slip fault system in the east. Our reconstructions are only compatible with geodynamic models involving an initial collision of India with a near-equatorial Trans-Tethyan subduction system at ~60 Ma, followed by a later collision with the Asian margin.

The rate of global-mean sea-level rise since 1900 has varied over time, but the contributing factors are still poorly understood 1 . Previous assessments found that the summed contributions of ice-mass loss, terrestrial water storage and thermal expansion of the ocean could not be reconciled with observed changes in global-mean sea level, implying that changes in sea level or some contributions to those changes were poorly constrained 2 , 3 . Recent improvements to observational data, our understanding of the main contributing processes to sea-level change and methods for estimating the individual contributions, mean another attempt at reconciliation is warranted. Here we present a probabilistic framework to reconstruct sea level since 1900 using independent observations and their inherent uncertainties. The sum of the contributions to sea-level change from thermal expansion of the ocean, ice-mass loss and changes in terrestrial water storage is consistent with the trends and multidecadal variability in observed sea level on both global and basin scales, which we reconstruct from tide-gauge records. Ice-mass loss—predominantly from glaciers—has caused twice as much sea-level rise since 1900 as has thermal expansion. Mass loss from glaciers and the Greenland Ice Sheet explains the high rates of global sea-level rise during the 1940s, while a sharp increase in water impoundment by artificial reservoirs is the main cause of the lower-than-average rates during the 1970s. The acceleration in sea-level rise since the 1970s is caused by the combination of thermal expansion of the ocean and increased ice-mass loss from Greenland. Our results reconcile the magnitude of observed global-mean sea-level rise since 1900 with estimates based on the underlying processes, implying that no additional processes are required to explain the observed changes in sea level since 1900. Observed global-mean sea-level rise since 1900 is reconciled with estimates based on the contributing processes, revealing budget closure within uncertainties and showing ice-mass loss from glaciers as a dominant contributor.

A whole-mantle seismic imaging technique, combining accurate wavefield computations with information contained in whole seismic waveforms, is used to reveal the presence of broad conduits beneath many of Earth’s surface hotspots, supporting the idea that these conduits are the source of hotspot volcanoes. Plume-like conduits beneath surface hotspots Scott French and Barbara Romanowicz use a whole-mantle seismic imaging technique, combining accurate wavefield computations with information contained in whole seismic waveforms, to reveal the presence of wide, quasi-vertical conduits beneath many of the Earth's surface hotspots. The conduits they image extend from the core–mantle boundary, where they are rooted in patches of strongly reduced shear velocity, and correspond to known locations of large ultralow-velocity zones beneath Hawaii, Iceland and Samoa, in support of the idea that they may be the source of hotspot volcanoes. As the conduits are broader than classical thermal plume tails, the authors suggest that they are long lived and may have a thermochemical origin. Plumes of hot upwelling rock rooted in the deep mantle have been proposed as a possible origin of hotspot volcanoes, but this idea is the subject of vigorous debate 1 , 2 . On the basis of geodynamic computations, plumes of purely thermal origin should comprise thin tails, only several hundred kilometres wide 3 , and be difficult to detect using standard seismic tomography techniques. Here we describe the use of a whole-mantle seismic imaging technique—combining accurate wavefield computations with information contained in whole seismic waveforms 4 —that reveals the presence of broad (not thin), quasi-vertical conduits beneath many prominent hotspots. These conduits extend from the core–mantle boundary to about 1,000 kilometres below Earth’s surface, where some are deflected horizontally, as though entrained into more vigorous upper-mantle circulation. At the base of the mantle, these conduits are rooted in patches of greatly reduced shear velocity that, in the case of Hawaii, Iceland and Samoa, correspond to the locations of known large ultralow-velocity zones 5 , 6 , 7 . This correspondence clearly establishes a continuous connection between such zones and mantle plumes. We also show that the imaged conduits are robustly broader than classical thermal plume tails, suggesting that they are long-lived 8 , and may have a thermochemical origin 9 , 10 , 11 . Their vertical orientation suggests very sluggish background circulation below depths of 1,000 kilometres. Our results should provide constraints on studies of viscosity layering of Earth’s mantle and guide further research into thermochemical convection.

The continental crust provides a record of Earth’s evolution. Analysis of the geochemical signature of continental crust formed since the Hadean points to the initiation of plate tectonics about 3 billion years ago. The continental crust is the principal record of conditions on the Earth during the past 4.4 billion years 1 , 2 . However, how the continental crust formed and evolved through time remains highly controversial 3 , 4 . In particular, the composition and thickness of juvenile continental crust are unknown. Here we show that Rb/Sr ratios can be used as a proxy for both the silica content and the thickness of the continental crust. We calculate Rb/Sr ratios of the juvenile crust for over 13,000 samples, with Nd model ages ranging from the Hadean to Phanerozoic. The ratios were calculated based on the evolution of Sr isotopes in the period between the T DM Nd model age and the crystallization of the samples analysed. We find that the juvenile crust had a low silica content and was largely mafic in composition during the first 1.5 billion years of Earth’s evolution, consistent with magmatism on a pre-plate tectonics planet. About 3 billion years ago, the Rb/Sr ratios of the juvenile continental crust increased, indicating that the newly formed crust became more silica-rich and probably thicker. This transition is in turn linked to the onset of plate tectonics 5 and an increase of continental detritus into the oceans 6 .

Formation of the Tibetan Plateau is generally ascribed to the Cenozoic India–Asia collision. However, the origin of along-strike deformation of the Indian mantle lithosphere, especially beneath the eastern Tibetan Plateau region, and its effect on the plateau’s eastward growth remain unclear. Here, we conduct multiscale seismic tomography to provide a revised structure of the Indian mantle lithosphere beneath the eastern Tibetan Plateau region. Our results demonstrate that the Indian mantle lithosphere is currently torn vertically along ~26° N, with its northern portion shallowly subducting northeastwards and the southern portion steeply subducting eastwards into the mantle transition zone. Analysis of tectonic and magmatic records is consistent with advancing and retreating migration of the slab tear after about 50 Myr ago. We suggest that the rigid Yangtze cratonic lithosphere tore the intruding cratonic Indian mantle lithosphere approximately 35 Myr ago, resulting in diverging shallow subduction. The subsequent Miocene rollback of the southeastern Indian mantle lithosphere is proposed to induce a giant turbo-engine-like flow that caused clockwise rotation of the plateau crust and underlying mantle around the eastern syntaxis, leading to differential eastward growth of the Tibetan Plateau. The Cenozoic eastward growth of the Tibetan Plateau can be explained by slab tear and the resulting mantle flow beneath the eastern region, according to analysis of seismic tomography, tectonic and magmatic records of the Indian mantle lithosphere.

Phase equilibria modelling of rocks from Western Australia confirms that the ancient continental crust could have formed by multistage melting of basaltic ‘parents’ along high geothermal gradients—a process incompatible with modern-style subduction. Early continents not formed by subduction Tim Johnson et al . perform phase equilibria modelling of the Coucal basalts from Western Australia and confirm their suitability as parent rocks of the Archaean continental crust. The authors suggest that these early crustal rocks were produced by 20–30 per cent melting along high geothermal gradients. They conclude that the production and stabilization of the first continents required a protracted, multistage process. When coupled with the high geothermal gradients, this suggests that the continents did not form by subduction. Instead it favours a 'stagnant lid' regime in the early Archaean eon in which a single, rigid plate lay over the mantle. The geodynamic environment in which Earth’s first continents formed and were stabilized remains controversial 1 . Most exposed continental crust that can be dated back to the Archaean eon (4 billion to 2.5 billion years ago) comprises tonalite–trondhjemite–granodiorite rocks (TTGs) that were formed through partial melting of hydrated low-magnesium basaltic rocks 2 ; notably, these TTGs have ‘arc-like’ signatures of trace elements and thus resemble the continental crust produced in modern subduction settings 3 . In the East Pilbara Terrane, Western Australia, low-magnesium basalts of the Coucal Formation at the base of the Pilbara Supergroup have trace-element compositions that are consistent with these being source rocks for TTGs. These basalts may be the remnants of a thick (more than 35 kilometres thick), ancient (more than 3.5 billion years old) basaltic crust 4 , 5 that is predicted to have existed if Archaean mantle temperatures were much hotter than today’s 6 , 7 , 8 . Here, using phase equilibria modelling of the Coucal basalts, we confirm their suitability as TTG ‘parents’, and suggest that TTGs were produced by around 20 per cent to 30 per cent melting of the Coucal basalts along high geothermal gradients (of more than 700 degrees Celsius per gigapascal). We also analyse the trace-element composition of the Coucal basalts, and propose that these rocks were themselves derived from an earlier generation of high-magnesium basaltic rocks, suggesting that the arc-like signature in Archaean TTGs was inherited from an ancestral source lineage. This protracted, multistage process for the production and stabilization of the first continents—coupled with the high geothermal gradients—is incompatible with modern-style plate tectonics, and favours instead the formation of TTGs near the base of thick, plateau-like basaltic crust 9 . Thus subduction was not required to produce TTGs in the early Archaean eon.