The interplay between recycled and primordial heterogeneities: predicting Earth's mantle dynamics via numerical modeling

2021 ◽  
Author(s):  
Matteo Desiderio ◽  
Anna J. P. Gülcher ◽  
Maxim D. Ballmer
Keyword(s):  
Lower Mantle ◽  
Mantle Convection ◽  
Large Scale ◽  
Numerical Models ◽  
Bulk Composition ◽  
Oceanic Lithosphere ◽  
Mantle Dynamics ◽  
Density Anomaly ◽  
Mantle Mineral ◽  
Intrinsic Strength

<p>According to geochemical and geophysical observations, Earth's lower mantle appears to be strikingly heterogeneous in composition. An accurate interpretation of these findings is critical to constrain Earth's bulk composition and long-term evolution. To this end, two main models have gained traction, each reflecting a different style of chemical heterogeneity preservation: the 'marble cake' and 'plum pudding' mantle. In the former, heterogeneity is preserved in the form of narrow streaks of recycled oceanic lithosphere, stretched and stirred throughout the mantle by convection. In the latter, domains of intrinsically strong, primordial material (enriched in the lower-mantle mineral bridgmanite) may resist convective entrainment and survive as coherent blobs in the mid mantle. Microscopic scale processes certainly affect macroscopic properties of mantle materials and thus reverberate on large-scale mantle dynamics. A cross-disciplinary effort is therefore needed to constrain present-day Earth structure, yet countless variables remain to be explored. Among previous geodynamic studies, for instance, only few have attempted to address how the viscosity and density of recycled and primordial materials affect their mutual mixing and interaction in the mantle.</p><p>Here, we apply the finite-volume code <strong>STAGYY</strong> to model thermochemical convection of the mantle in a 2D spherical-annulus geometry. All models are initialized with a lower, primordial layer and an upper, pyrolitic layer (i.e., a mechanical mixture of basalt and harzburgite), as is motivated by magma-ocean solidification studies. We explore the effects of material properties on the style of mantle convection and heterogeneity preservation. These parameters include (i) the intrinsic strength of basalt (viscosity), (ii) the intrinsic density of basalt, and (iii) the intrinsic strength of the primordial material.</p><p>Our preliminary models predict a range of different mantle mixing styles. A 'marble cake'-like regime is observed for low-viscosity primordial material (~30 times weaker than the ambient mantle), with recycled oceanic lithosphere preserved as streaks and thermochemical piles accumulating near the core-mantle boundary. Conversely, 'plum pudding' primordial blobs are also preserved when the primordial material is relatively strong, in addition to the 'marble cake' heterogeneities mentioned above. Most notably, however, the rheology and the density anomaly of basalt affect the appearance of both recycled and primordial heterogeneities. In particular, they control the stability, size and geometry of thermochemical piles, the enhancement of basaltic streaks in the mantle transition zone, and they influence the style of primordial material preservation. These results indicate the important control that the physical properties of mantle constituents exert on the style of mantle convection and mixing over geologic time. Our numerical models offer fresh insights into these processes and may advance our understanding of the composition and structure of Earth's lower mantle.</p>

The formation, preservation and seismic signatures of chemical heterogeneities in the lower mantle

2020 ◽  
Author(s):  
Anna J. P. Gülcher ◽  
Maxim D. Ballmer ◽  
Paul J. Tackley ◽  
Paula Koelemeijer
Keyword(s):  
Physical Properties ◽  
Lower Mantle ◽  
Numerical Models ◽  
Bulk Composition ◽  
Oceanic Lithosphere ◽  
Global Scale ◽  
Seismic Velocities ◽  
Mantle Dynamics ◽  
Wide Range ◽  
Scientific Challenge

<p>Despite stirring by vigorous convection over billions of years, the Earth’s lower mantle appears to be chemically heterogeneous on various length scales. Constraining this heterogeneity is key for assessing Earth’s bulk composition and thermochemical evolution, but remains a scientific challenge that requires cross-disciplinary efforts. On scales below ~1 km, the concept of a “marble cake” mantle has gained wide acceptance, emphasising that recycled oceanic lithosphere, deformed into streaks of depleted and enriched compositions, makes up much of the mantle. On larger scales (10s-100s of km), compositional heterogeneity may be preserved by delayed mixing of this marble cake with either intrinsically-dense or intrinsically-strong materials. Intrinsically dense materials may accumulate as piles at the core-mantle boundary, while intrinsically viscous domains (e.g., enhanced in the strong mineral bridgmanite) may survive as “blobs” in the mid-mantle for large timescales, such as plums in the mantle “plum pudding”<sup>1,2</sup>. While many studies have explored the formation and preservation of either intrinsically-dense (recycled) or intrinsically-strong (primordial) heterogeneity, only few if any have quantified mantle dynamics in the presence of different types of heterogeneity with distinct physical properties.<span> </span></p><p>To address this objective, we use state-of-the-art 2D numerical models of global-scale mantle convection in a spherical-annulus geometry. We explore the effects of the <em>(i)</em> physical properties of primordial material (density, viscosity), <em>(ii)</em> temperature/pressure dependency of viscosity, <em>(iii)</em> lithospheric yielding strength, and <em>(iv)</em> Rayleigh number on mantle dynamics and mixing. Models predict that primordial heterogeneity is preserved in the lower mantle over >4.5 Gyr as discrete blobs for high intrinsic viscosity contrast (>30x) and otherwise for a wide range of parameters. In turn, recycled oceanic crust is preserved in the lower mantle as “marble cake” streaks or piles, particularly in models with a relatively cold and stiff mantle. Importantly, these recycled crustal heterogeneities can co-exist with primordial blobs, with piles often tending to accumulate beneath the primordial domains. This suggests that the modern mantle may be in a hybrid state between the “marble cake” and “plum pudding” styles.<span> </span></p><p>Finally, we put our model predictions in context with recent discoveries from seismology. We calculate synthetic seismic velocities from predicted temperatures and compositions, and compare these synthetics to tomography models, taking into account the limited resolution of seismic tomography. Convection models including preserved bridgmanite-enriched domains along with recycled piles have the potential of reconciling recent seismic observations of lower-mantle heterogeneity<sup>3</sup> with the geochemical record from ocean-island basalts<sup>4,5</sup>, and are therefore relevant for assessing Earth’s bulk composition and long-term evolution.<span> </span></p><p><sup>1</sup> Ballmer et al. (2017), <em>Nat. Geosci</em>., 10.1038/ngeo2898<br><sup>2</sup> Gülcher et al. (in review), <em>EPSL</em>: Variable dynamic styles of primordial heterogeneity preservation in Earth’s lower mantle <br><sup>3</sup> Waszek et al. (2018), <em>Nat. Comm., </em>10.1038/s41467-017-02709-4 <br><sup>4</sup> Hofmann (1997), <em>Nature, </em>10.1038/385219a0; <br><sup>5</sup> Mundl et al. (2017), <em>Science, </em>10.1126/science.aal4179</p>

The importance of phase morphology for rheology of ferropericlase-bridgmanite mixtures

2021 ◽  
Author(s):  
Marcel Thielmann ◽  
Gregor Golabek ◽  
Hauke Marquardt
Keyword(s):  
Lower Mantle ◽  
Mantle Convection ◽  
Effective Viscosity ◽  
Large Scale ◽  
Numerical Models ◽  
Phase Morphology ◽  
Strong Impact ◽  
Analytical Approximations ◽  
The Impact ◽  
Strong Control

<p>The rheology of the Earth’s lower mantle is poorly constrained due to a lack of knowledge of the rheological behaviour of its constituent minerals. In addition, the lower mantle does not consist of only a single, but of multiple mineral phases with differing deformation behaviour. The rheology of Earth’s lower mantle is thus not only controlled by the rheology of its individual constituents (bridgmanite and ferropericlase), but also by their interplay during deformation. This is particularly important when the viscosity contrast between the different minerals is large. Experimental studies have shown that ferropericlase may be significantly weaker than bridgmanite and may thus exert a strong control on lower mantle rheology.</p><p>Here, we thus explore the impact of phase morphology on the rheology of a ferropericlase-bridgmanite mixture using numerical models. We find that elongated ferropericlase structures within the bridgmanite matrix significantly lower the effective viscosity, even in cases where no interconnected network of weak ferropericlase layers has been formed. In addition to the weakening, elongated ferropericlase layers result in a strong viscous anisotropy. Both of these effects may have a strong impact on lower mantle dynamics, which makes is necessary to develop upscaling methods to include them in large-scale mantle convection models. We develop a numerical-statistial approach to link the statistical properties of a ferropericlase-bridgmanite mixture to its effective viscosity tensor. With this approach, both effects are captured by analytical approximations that have been derived to describe the evolution of the effective viscosity (and its anisotropy) of a two-phase medium with aligned elliptical inclusions, thus allowing to include these microscale processes in large-scale mantle convection models.</p>

scholarly journals Neo-Tethys geodynamics and mantle convection: from extension to compression in Africa and a conceptual model for obduction

2016 ◽  
Vol 53 (11) ◽  
pp. 1190-1204 ◽  
Author(s):  
Laurent Jolivet ◽  
Claudio Faccenna ◽  
Philippe Agard ◽  
Dominique Frizon de Lamotte ◽  
Armel Menant ◽  
...  
Keyword(s):  
Transition Zone ◽  
Lower Mantle ◽  
Mantle Convection ◽  
Large Scale ◽  
Time Window ◽  
Numerical Models ◽  
Conveyor Belt ◽  
Arabian Plate ◽  
African Plate ◽  
Northern Margin

Since the Mesozoic, Africa has been under extension with shorter periods of compression associated with obduction of ophiolites on its northern margin. Less frequent than “normal” subduction, obduction is a first order process that remains enigmatic. The closure of the Neo-Tethys Ocean, by the Upper Cretaceous, is characterized by a major obduction event, from the Mediterranean region to the Himalayas, best represented around the Arabian Plate, from Cyprus to Oman. These ophiolites were all emplaced in a short time window in the Late Cretaceous, from ∼100 to 75 Ma, on the northern margin of Africa, in a context of compression over large parts of Africa and Europe, across the convergence zone. The scale of this process requires an explanation at the scale of several thousands of kilometres along strike, thus probably involving a large part of the convecting mantle. We suggest that alternating extension and compression in Africa could be explained by switching convection regimes. The extensional situation would correspond to steady-state whole-mantle convection, Africa being carried northward by a large-scale conveyor belt, while compression and obduction would occur when the African slab penetrates the upper–lower mantle transition zone and the African plate accelerates due to increasing plume activity, until full penetration of the Tethys slab in the lower mantle across the 660 km transition zone during a 25 Myr long period. The long-term geological archives on which such scenarios are founded can provide independent time constraints for testing numerical models of mantle convection and slab–plume interactions.

scholarly journals Feedbacks between a non-Newtonian upper mantle, mantle viscosity structure and mantle dynamics

2020 ◽  
Vol 224 (2) ◽  
pp. 961-972
Author(s):  
A G Semple ◽  
A Lenardic
Keyword(s):  
Upper Mantle ◽  
Lower Mantle ◽  
Mantle Convection ◽  
Mantle Flow ◽  
Mantle Dynamics ◽  
Plate Motions ◽  
Low Viscosity ◽  
Mantle Viscosity ◽  
Flow Feature ◽  
Mantle Rheology

SUMMARY Previous studies have shown that a low viscosity upper mantle can impact the wavelength of mantle flow and the balance of plate driving to resisting forces. Those studies assumed that mantle viscosity is independent of mantle flow. We explore the potential that mantle flow is not only influenced by viscosity but can also feedback and alter mantle viscosity structure owing to a non-Newtonian upper-mantle rheology. Our results indicate that the average viscosity of the upper mantle, and viscosity variations within it, are affected by the depth to which a non-Newtonian rheology holds. Changes in the wavelength of mantle flow, that occur when upper-mantle viscosity drops below a critical value, alter flow velocities which, in turn, alter mantle viscosity. Those changes also affect flow profiles in the mantle and the degree to which mantle flow drives the motion of a plate analogue above it. Enhanced upper-mantle flow, due to an increasing degree of non-Newtonian behaviour, decreases the ratio of upper- to lower-mantle viscosity. Whole layer mantle convection is maintained but upper- and lower-mantle flow take on different dynamic forms: fast and concentrated upper-mantle flow; slow and diffuse lower-mantle flow. Collectively, mantle viscosity, mantle flow wavelengths, upper- to lower-mantle velocities and the degree to which the mantle can drive plate motions become connected to one another through coupled feedback loops. Under this view of mantle dynamics, depth-variable mantle viscosity is an emergent flow feature that both affects and is affected by the configuration of mantle and plate flow.

Coupled dynamics of primordial and recycled heterogeneity in Earth's lower mantle, and their present-day seismic signatures

2021 ◽  
Author(s):  
Anna J. P. Gülcher ◽  
Maxim D. Ballmer ◽  
Paul J. Tackley
Keyword(s):  
Oceanic Crust ◽  
Seismic Tomography ◽  
Lower Mantle ◽  
Large Scale ◽  
Numerical Models ◽  
Global Scale ◽  
Physical Parameters ◽  
Compositional Heterogeneity ◽  
Seismic Velocities ◽  
S Wave

<p>The nature of compositional heterogeneity in Earth’s lower mantle is a long-standing puzzle that can inform about the thermochemical evolution and dynamics of our planet. On relatively small scales (<1km), streaks of recycled oceanic crust (ROC) and lithosphere are distributed and stirred throughout the mantle, creating a “marble cake” mantle. On larger scales (10s-100s of km), compositional heterogeneity may be preserved by delayed mixing of this marble cake with either intrinsically-dense or -strong materials of e.g. primordial origin. Intrinsically-dense materials may accumulate as piles at the core-mantle boundary, while intrinsically viscous (e.g., enhanced in the strong mineral MgSiO<sub>3 </sub>bridgmanite) may survive as blobs in the mid-mantle for large timescales (i.e., as plums in the mantle “plum pudding”). So far, only few, if any, studies have quantified mantle dynamics in the presence of different types of heterogeneity with distinct physical properties.<br><br>Here, we use 2D numerical models of global-scale mantle convection to investigate the coupled evolution and mixing of (intrinsically-dense) recycled and (intrinsically-strong) primordial material. We explore the effects of ancient compositional layering of the mantle, as motivated by magma-ocean solidification studies, and the physical parameters of the primordial material. Over a wide parameter range, primordial and recycled heterogeneity is predicted to coexist with each other. Primordial material usually survives as mid-to-large scale blobs in the mid-mantle, and this preservation is largely independent on the initial primordial-material volume. In turn, recycled oceanic crust (ROC) persists as piles at the base of the mantle and as small streaks everywhere else. The robust coexistence between recycled and primordial materials in the models indicate that the modern mantle may be in a hybrid state between the “marble cake” and “plum pudding” styles.<br><br>Finally, we put our model predictions in context with geochemical studies on early Earth dynamics as well as seismic discoveries of present-day lower-mantle heterogeneity. For the latter, we calculate synthetic seismic velocities from output model fields, and compare these synthetics to tomography models, taking into account the limited resolution of seismic tomography. Because of the competing effects of compositional and thermal anomalies on S-wave velocities, it is difficult to identify mid-mantle bridgmanitic domains in seismic tomography images. This result suggests that, if present, bridgmanitic domains in the mid-mantle may be “hidden” from seismic tomographic studies, and other approaches are needed to establish the presence/absence of these domains in the present-day deep Earth.</p>

Strain-weakening rheology in Earth’s lower mantle: a multi-scale numerical endeavour

2020 ◽  
Author(s):  
Gregor J. Golabek ◽  
Anna J. P. Gülcher ◽  
Marcel Thielmann ◽  
Paul J. Tackley ◽  
Maxim D. Ballmer
Keyword(s):  
Lower Mantle ◽  
Mantle Convection ◽  
Numerical Models ◽  
Order Effect ◽  
Small Scale ◽  
Localized Deformation ◽  
Earth Planet ◽  
Multi Scale ◽  
Macro Scale ◽  
Heterogeneous Rocks

<p>Rocks in the Earth’s interior are not homogeneous but consist of different mineralogical phases with different rheological properties. Deformation of heterogeneous rocks is thus also heterogeneous, and strongly depends on the rheological contrasts and spatial distribution of the mineral phases. In Earth’s lower mantle, the main rock constituents are bridgmanite (Br) and smaller amounts of ferropericlase (Fp). Bridgmanite is substantially stronger than ferropericlase [1]. Recent studies propose that lower mantle rheology is highly dependent on the relative mineral abundances and distribution of these two phases [1,2]. It has been suggested that for bridgmanite-depleted compositions, the viscosity decreases with accumulating strain due to the interconnection of the weaker ferropericlase. This implies that deformation may localize in the lower mantle, potentially aiding the formation and preservation of compositionally distinct and “hidden” reservoirs away from these regions of localized deformation [3]. Therefore, understanding the rheological nature of Br-Fp aggregates on a small-scale is crucial for assessing the dynamics of global mantle convection. Here, we address this objective with multi-scale numerical approaches.  </p><p>Using a numerical-statistical approach, a connection between ferropericlase morphology and effective rheology of Earth’s lower mantle has recently been established [4]. Results show that bulk-rock weakening depends on the topology of the weak phase as well on its rheology, but also that significant rheological weakening can already be achieved when ferropericlase does not (yet) form an interconnected weak layer.</p><p>In a second suite of models, we implement a macro-scale description of strain-weakening based on the micro-scale solutions found in [4] in a global mantle convection model to test the first-order effect of strain weakening on convection dynamics in the lower mantle. We present 2D numerical models of thermochemical convection in a spherical annulus geometry [5] that include a new implementation of tracking the strain ellipse at each tracer through time. We further allow lower mantle materials to rheologically weaken once a certain strain threshold has been reached. Preliminary results indicate that strain localizes along both up- and downwellings in the lower mantle and that rheological weakening has a stabilizing effect on these conduits. </p><p>This multi-scale approach is essential for addressing lower-mantle rheological behavior and our results form an important step towards addressing the feasibility of isolated, long-lived geochemical reservoirs in Earth’s lower mantle.</p><p>[1] Yamazaki and Karato (2001), Am. Mineral. 86, 385-391. [2] Girard et al. (2016), Science 351, 144-147. [3] Ballmer et al. (2017), Nat. Geosci. 10, 236-240. [4] Thielmann et al. (2020), Geochem. Geophys. Geosyst., doi:10.1029/2019GC008688. [5] Hernlund and Tackley (2008), Phys. Earth Planet. Int. 171, 48–54.</p>

Isostatic and dynamic controls on neotectonic differential vertical movements and sediment transport reorganization of the Pannonian Basin, Central Europe

2020 ◽  
Author(s):  
Attila Balázs ◽  
Ádám Kovács ◽  
Orsolya Sztanó ◽  
Liviu Matenco ◽  
László Fodor ◽  
...  
Keyword(s):  
Large Scale ◽  
Pannonian Basin ◽  
Numerical Models ◽  
Gravity Anomalies ◽  
Seismic Structure ◽  
Dynamic Topography ◽  
Mantle Dynamics ◽  
Vertical Movements ◽  
Preliminary Model ◽  
Sedimentary Fill

<p>Extensive geophysical studies on gravity anomalies and seismic structure of the Pannonian Basin have determined that this extensional sedimentary basin is more elevated than predicted by Airy-type isostatic compensation models. European regional models assuming a two-layered lithosphere containing a uniform crust and a lithospheric mantle estimated ca. 750-1000 meters difference between the actual and calculated isostatic topography for the Pannonian region.</p><p>We have revisited this early finding and calculated a refined residual topography map of the Pannonian Basin that also takes into account the low-density sedimentary fill. We show that the actual residual topography of the eastern part of the region is much lower than previously thought and ca. 4-500 meters of positive residual topography characterizes the central and western part of the Pannonian Basin.</p><p>In order to interpret the observed residual topography of the basin we carried out a series of elasto-visco-plastic thermo-mechanical numerical models. Our simulation of the last 9Myr covering the classical  “post-rift” phase of the Pannonian Basin analyzes forcing factors, such as asthenospheric-scale mantle convection, elastic flexure of the lithosphere due to increased external stress and sediment re-distribution, and ductile lower crustal deformation. The large-scale positive residual topography is dominantly controlled by mantle dynamics.</p><p>Finally, 3D stratigraphic numerical forward modelling has been carried out by DionisosFlow, constrained by our previously calculated tectonic scenario. We analyzed the substantial reorganization of the main sedimentary transport routes in the Pannonian Basin mainly controlled by the development of the observed positive dynamic topography of the basin. Our preliminary model results are in good agreement with geological records, such as the ca. 200 km Pliocene eastward migration of the Paleo-Danube drainage network.</p>

scholarly journals Surface and mantle records reveal an ancient slab tear beneath Gondwana

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Guido M. Gianni ◽  
César Navarrete ◽  
Silvana Spagnotto
Keyword(s):  
Lower Mantle ◽  
Subduction Zones ◽  
Large Scale ◽  
P Wave ◽  
Late Triassic ◽  
Mantle Dynamics ◽  
Geological Record ◽  
Slab Tear ◽  
Oceanic Plates ◽  
Slab Tearing

AbstractVertical slab-tearing has been widely reported in modern convergent settings profoundly influencing subduction and mantle dynamics. However, evaluating a similar impact in ancient convergent settings, where oceanic plates have been subducted and the geological record is limited, remains challenging. In this study, we correlate the lower mantle structure, which retained the past subduction configuration, with the upper-plate geological record to show a deep slab rupture interpreted as a large-scale tearing event in the early Mesozoic beneath southwestern Gondwana. For this purpose, we integrated geochronological and geological datasets with P-wave global seismic tomography and plate-kinematic reconstructions. The development of a Late Triassic-Early Jurassic slab-tearing episode supports (i) a slab gap at lower mantle depths, (ii) a contrasting spatiotemporal magmatic evolution, (iii) a lull in arc activity, and (iv) intraplate extension and magmatism in the Neuquén and Colorado basins. This finding not only has implications for identifying past examples of a fundamental process that shapes subduction zones, but also illustrates an additional mechanism to trigger slab-tearing in which plate rupture is caused by opposite rotation of slab segments.

scholarly journals The impact of rheological uncertainty on dynamic topography predictions: Gearing up for dynamic topography models consistent with observations

2019 ◽  
Author(s):  
Ömer F. Bodur ◽  
Patrice F. Rey
Keyword(s):  
Mantle Convection ◽  
Numerical Models ◽  
Mantle Flow ◽  
Dynamic Topography ◽  
Dynamic Component ◽  
Density Anomaly ◽  
Low Viscosity ◽  
Local Reduction ◽  
Non Linear ◽  
The Impact

Abstract. Much effort has been given on extracting the dynamic component of the Earth’s topography, which is driven by density heterogeneities in the mantle. Seismically mapped density anomalies have been used as an input into mantle convection models to predict the present-day mantle flow and stresses applied on the Earth’s surface, resulting in dynamic topography. However, mantle convection models give dynamic topographies generally larger by a factor of ∼2 compared to dynamic topographies estimated from residual topography after extraction of the isostatically compensated topography. Our 3D thermo-mechanical numerical experiments suggest that this discrepancy can be explained by the use of a viscosity model, which doesn’t account for non-linear viscosity behaviour. In this paper, we numerically model the dynamic topography induced by a spherical density anomaly embedded into the mantle. When we use non-linear viscosities, our numerical models predict dynamic topographies lesser by a factor of ∼2 than those derived from numerical models using isoviscous rheology. This reduction in dynamic topography is explained by either the formation of a low viscosity channel beneath the lithosphere, or a decrease in thickness of the mechanical lithosphere due to induced local reduction in viscosity. Furthermore, we show that uncertainties related to activation volume and fluid activity, lead to variations in dynamic topography of about 20 %.

scholarly journals Mantle plumes and mantle dynamics in the Wilson cycle

2019 ◽  
Vol 470 (1) ◽  
pp. 87-103 ◽  
Author(s):  
Philip J. Heron
Keyword(s):  
Mantle Convection ◽  
Large Scale ◽  
Thermal Evolution ◽  
Mantle Flow ◽  
Mantle Plumes ◽  
Mantle Dynamics ◽  
The Core ◽  
Deep Mantle ◽  
Igneous Provinces ◽  
Wilson Cycle

AbstractThis review discusses the thermal evolution of the mantle following large-scale tectonic activities such as continental collision and continental rifting. About 300 myr ago, continental material amalgamated through the large-scale subduction of oceanic seafloor, marking the termination of one or more oceanic basins (e.g. Wilson cycles) and the formation of the supercontinent Pangaea. The present day location of the continents is due to the rifting apart of Pangaea, with the dispersal of the supercontinent being characterized by increased volcanic activity linked to the generation of deep mantle plumes. The discussion presented here investigates theories regarding the thermal evolution of the mantle (e.g. mantle temperatures and sub-continental plumes) following the formation of a supercontinent. Rifting, orogenesis and mass eruptions from large igneous provinces change the landscape of the lithosphere, whereas processes related to the initiation and termination of oceanic subduction have a profound impact on deep mantle reservoirs and thermal upwelling through the modification of mantle flow. Upwelling and downwelling in mantle convection are dynamically linked and can influence processes from the crust to the core, placing the Wilson cycle and the evolution of oceans at the forefront of our dynamic Earth.

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