ORCID Profile
0000-0003-2131-8723
Current Organisations
ETH Zürich
,
Monash University
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Geology | Geodynamics | Tectonics | Geophysics | Palaeoclimatology | Basin Analysis | Atmospheric Dynamics | Geophysics Not Elsewhere Classified | Geotectonics | Numerical Computation
Expanding Knowledge in the Earth Sciences | Oil and Gas Exploration | Atmospheric Processes and Dynamics | Climate Change Models | Climate and Climate Change not elsewhere classified | Other |
Publisher: Elsevier BV
Date: 03-2010
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-4566
Abstract: The Earth has evolved into a habitable planet through ongoing and complex cycling. Decades of field studies, geochemical analyses and computational approaches to integrate data into feasible geodynamic models reveal that Earth& #8217 s evolution was not linear but evolved in discrete phases. The timing of changes between these phases, their loci within Earth& #8217 s crust or between discrete cratonic terranes, and most importantly the drivers or tipping point for these changes, remain elusive.Integrating the record from the continental archive with knowledge of the ongoing cooling of the mantle and lithospheric rheology (parametrized for its evolving thermal state) allows us to determine that a number of different tectonic modes operated through the early history of the Earth. The temporal boundaries between these proposed different phases in tectonic mode are approximate, transitional, and correspond with the first recording of a key feature of that phase.Initial accretion and the moon forming impact resulted in a proto-Earth phase (ca. 4.57-4.45 Ga) likely characterized by a magma ocean. Its solidification produced the primitive Earth lithosphere that extended from ca. 4.45-3.80 Ga, which based on the very minor fragments preserved in younger cratons provides evidence for intra-lithospheric reworking, but which also likely involved intermittent and partial recycling of the lid through mantle overturn and meteoritic impacts. Evidence for craton formation and stabilization during the primitive (ca. 3.8 Ga to 3.2 Ga), and juvenile (ca. 3.2 Ga to 2.5 Ga) phases of Earth evolution likely reflects some degree of coupling between the convecting mantle and a lithosphere initially weak enough to favour an internally deformable, squishy-lid behaviour. These regions of deformable lithosphere likely oscillated spatially and temporally with regions of more rigid, plate like, behaviour leading to a transition to global plate tectonics by the end of the Archean (ca. 2.5 Ga). Evidence for assembly of rigid cratonic blocks in the late Archean along with their subsequent rifting and breakup followed by their reassembly along major linear orogenic belts in the Paleoproterozoic marks the clear inception of the supercontinent cycle in response to a plate tectonic framework of oceans opening and closing.Since solidification of the magma ocean early in Earth history, the available record suggests some degree of mantle-lithosphere coupling. The development and stabilization of cratons from 3.8-2.5 Ga provides evidence for the progressive development of rigid lithosphere and represents the inexorable precursor to the development of plate tectonics.
Publisher: Informa UK Limited
Date: 22-01-2019
Publisher: Elsevier BV
Date: 15-10-2007
Publisher: Elsevier BV
Date: 02-2012
Publisher: American Association for the Advancement of Science (AAAS)
Date: 30-10-2020
Abstract: Ocean floor lavas from an active spreading ridge keep a geochemical memory of an Early Cretaceous subduction zone.
Publisher: American Geophysical Union (AGU)
Date: 04-2009
DOI: 10.1029/2008GC002348
Publisher: Elsevier BV
Date: 05-2013
Publisher: Springer Science and Business Media LLC
Date: 19-07-2017
DOI: 10.1038/NCOMMS15992
Abstract: The formation of the Tibetan plateau during the India-Asia collision remains an outstanding issue. Proposed models mostly focus on the different styles of Tibetan crustal deformation, yet these do not readily explain the observed variation of deformation and deep structures along the collisional zone. Here we use three-dimensional numerical models to evaluate the effects of crustal rheology on the formation of the Himalayan-Tibetan orogenic system. During convergence, a weaker Asian crust allows strain far north within the upper plate, where a wide continental plateau forms behind the orogeny. In contrast, a stronger Asian crust suppresses the plateau formation, while the orogeny accommodates most of the shortening. The stronger Asian lithosphere is also forced beneath the Indian lithosphere, forming a reversed-polarity underthrusting. Our results demonstrate that the observed variations in lithosphere deformation and structures along the India-Asia collision zone are primarily controlled by the strength heterogeneity of the Asian continental crust.
Publisher: Oxford University Press (OUP)
Date: 16-03-2020
DOI: 10.1093/GJI/GGAA125
Abstract: The Tibetan crust is sliced by several east–west trending suture zones. The role of these suture zones in the evolution of the Himalayan range and Tibetan plateau remains unclear. Here we use 3-D thermomechanical simulations to investigate the role of pre-existing weak zones within the Asian Plate in the formation of orogen and plateau growth during continental collision. Our results show that partitioning of deformation along the convergent margin leads to scraping off of crustal material into an orogenic wedge above the margin and crustal thickening in the retro-continent, eventually forming a large orogenic plateau in front of the indenter. Pre-existing weak zone(s) within the retro-continent is reactivated at the early stage of convergence, and facilitates the northward propagation of strain and widening of the orogenic plateau. The northernmost weak zone sets the northern limit of the Tibetan plateau. Our models also show rheological weakening of the congested buoyant crust within the collisional zone drives wedge-type exhumation of deeply buried crust at the southern flank of the plateau, which may explain the formation of the Greater Himalayan Sequence.
Publisher: Elsevier BV
Date: 08-2016
Publisher: Elsevier BV
Date: 08-2016
Publisher: American Geophysical Union (AGU)
Date: 10-2020
DOI: 10.1029/2020TC006339
Publisher: Elsevier BV
Date: 07-2021
Publisher: Elsevier BV
Date: 10-2007
Publisher: American Geophysical Union (AGU)
Date: 11-2014
DOI: 10.1002/2014GC005507
Publisher: Springer Science and Business Media LLC
Date: 23-11-2011
DOI: 10.1038/NATURE10596
Abstract: The building of the Andes results from the subduction of the oceanic Nazca plate underneath the South American continent. However, how and why the Andes and their curvature, the Bolivian orocline, formed in the Cenozoic era (65.5 million years (Myr) ago to present), despite subduction continuing since the Mesozoic era (251.0-65.5 Myr ago), is still unknown. Three-dimensional numerical subduction models demonstrate that variations in slab thickness, arising from the Nazca plate's age at the trench, produce a cordilleran morphology consistent with that observed. The age-dependent sinking of the slab in the mantle drives traction towards the trench at the base of the upper plate, causing it to thicken. Thus, subducting older Nazca plate below the Central Andes can explain the locally thickened crust and higher elevations. Here we demonstrate that resultant thickening of the South American plate modifies both shear force gradients and migration rates along the trench to produce a concave margin that matches the Bolivian orocline. Additionally, the varying forcing along the margin allows stress belts to form in the upper-plate interior, explaining the widening of the Central Andes and the different tectonic styles found on their margins, the Eastern and Western Cordilleras. The rise of the Central Andes and orocline formation are directly related to the local increase of Nazca plate age and an age distribution along the margin similar to that found today the onset of these conditions only occurred in the Eocene epoch. This may explain the enigmatic delay of the Andean orogeny, that is, the formation of the modern Andes.
Publisher: American Geophysical Union (AGU)
Date: 15-05-2018
DOI: 10.1029/2017GL076948
Publisher: American Geophysical Union (AGU)
Date: 12-2016
DOI: 10.1002/2016JB013005
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-904
Abstract: & & The collision of India and Eurasia since ~50 Ma has resulted in a broad range of deformation along the Himalaya-Tibetan orogeny, accommodating & km of convergence. The region is characterised by the Tibetan Plateau, the Himalayan internal units and fold-and-thrust belt from North to South. These formed as a consequence of a convergence history characterised by a progressive decrease in velocity, from ~10 cm/yr 50 Ma, to ~8 cm/yr 42.5 Ma and to present-day values of ~4 cm/yr around 20 Ma. Here, we test the controls of such a convergence velocity history on the orogeny of a viscoplastic wedge during collision, above a subducting continental lithosphere. We compare numerical models simulating India-Asia plate convergence and collision, comparing the structures observed throughout the evolution with those observed in the Himalayan-Tibetan region. The models display distinct phases of growth and structural style evolution in the Himalayan-Tibetan region that are a result of the change in convergence velocity and long-term collision. After an initial stacking, the high convergence velocity forces deformation migration towards the upper plate, where a plateau forms, while late stage slowdown of collision favours the formation of the Himalayan fold-and-thrust belt. While the latter is in agreement with the structuring of the southermost domains and the South Tibetan Detachment (STD) fault, the former provide constraints to the initial uplift of the Tibetan Plateau.& &
Publisher: Elsevier BV
Date: 05-2020
Publisher: Elsevier BV
Date: 11-2012
Publisher: American Geophysical Union (AGU)
Date: 03-2018
DOI: 10.1002/2017GC007199
Publisher: Geological Society of America
Date: 20-08-2019
DOI: 10.1130/G46239.1
Abstract: Thermomechanical models of mantle convection and melting in an inferred hotter Archean Earth show the emergence of pressure-temperature (P-T) regimes that resemble present-day plate tectonic environments yet developed within a non–plate tectonics regime. The models’ P-T gradients are compatible with those inferred from evolving tonalite-trondhjemite-granodiorite series rocks and the paired metamorphic belt record, supporting the feasibility of ergent and convergent tectonics within a mobilized, yet laterally continuous, lithospheric lid. “Hot” P-T gradients of 10–20 °C km–1 form along asymmetric lithospheric drips, then migrate to areas of deep lithospheric downwelling within ∼300–500 m.y., where they are overprinted by high-pressure warm and, later, cold geothermal signatures, up to ∼8 °C km–1. Comparisons with the crustal production and reworking record suggest that this regime emerged in the Hadean.
Publisher: Springer Science and Business Media LLC
Date: 02-2008
DOI: 10.1038/NATURE06691
Abstract: It is well accepted that subduction of the cold lithosphere is a crucial component of the Earth's plate tectonic style of mantle convection. But whether and how subducting plates penetrate into the lower mantle is the subject of continuing debate, which has substantial implications for the chemical and thermal evolution of the mantle. Here we identify lower-mantle slab penetration events by comparing Cenozoic plate motions at the Earth's main subduction zones with motions predicted by fully dynamic models of the upper-mantle phase of subduction, driven solely by downgoing plate density. Whereas subduction of older, intrinsically denser, lithosphere occurs at rates consistent with the model, younger lithosphere (of ages less than about 60 Myr) often subducts up to two times faster, while trench motions are very low. We conclude that the most likely explanation is that older lithosphere, subducting under significant trench retreat, tends to lie down flat above the transition to the high-viscosity lower mantle, whereas younger lithosphere, which is less able to drive trench retreat and deforms more readily, buckles and thickens. Slab thickening enhances buoyancy (volume times density) and thereby Stokes sinking velocity, thus facilitating fast lower-mantle penetration. Such an interpretation is consistent with seismic images of the distribution of subducted material in upper and lower mantle. Thus we identify a direct expression of time-dependent flow between the upper and lower mantle.
Publisher: Copernicus GmbH
Date: 28-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-11060
Abstract: & & Understanding the controls on large magnitude seismicity occurrence remains an open challenge, yet a pressing one, for the exceptional hazard associated with earthquakes. Different parameters are proposed to exert control on the generation and propagation of megathrust earthquakes and untangling their complex interactions across scales remains challenging. Here, we use explainable artificial intelligence to unravel the interactions between different parameters and elucidate the underlying mechanisms. We use three types of datasets from a number of convergent margins: & em& a& /em& ) a catalogue of earthquake hypocentre and rupture, & em& b& /em& ) geophysical observations of subduction zones properties (e.g., gravity, bathymetric roughness, sediment thickness), and& em& c& /em& ) the distribution of stress within the slab due to slab pull calculated from flexure models. These constitute the three types of nodes in the input layer of a Fully Connected Network (FCN) trained to classify earthquake magnitude embedding the state of the system (& em& b& /em& ), the driving mechanism (& em& c& /em& ) and the resulting seismicity (& em& a& /em& ). We then analyse the trained network using Layer-wise Relevance Propagation (LRP) to determine the relative weights of the input nodes, providing relevant constraints on the mechanisms that dominate the seismicity in a region, their scale and likelihood.& &
Publisher: Elsevier BV
Date: 07-2009
Publisher: Elsevier BV
Date: 11-2017
Publisher: Elsevier BV
Date: 2011
Publisher: Elsevier BV
Date: 11-2013
Publisher: Elsevier BV
Date: 2018
Publisher: American Geophysical Union (AGU)
Date: 07-2010
DOI: 10.1029/2010GL044054
Publisher: Elsevier BV
Date: 12-2017
Publisher: American Geophysical Union (AGU)
Date: 10-2018
DOI: 10.1029/2017TC004926
Publisher: American Geophysical Union (AGU)
Date: 09-2013
DOI: 10.1002/GGGE.20171
Publisher: American Geophysical Union (AGU)
Date: 18-09-2017
DOI: 10.1002/2017GL074686
Publisher: American Geophysical Union (AGU)
Date: 2013
DOI: 10.1002/GGGE.20055
Publisher: Elsevier BV
Date: 07-2019
Publisher: Springer Science and Business Media LLC
Date: 02-12-2020
Publisher: American Geophysical Union (AGU)
Date: 11-11-2019
DOI: 10.1029/2019GL085212
Abstract: Recent geophysical observations report the presence of a very weak and thin upper asthenosphere underneath subducting oceanic plates at convergent margins. Along these margins, trench migrations are significantly slower than plate convergence rates. We use numerical models to assess the role of a weak upper asthenospheric layer on plate and trench motions. We show that the presence of this layer alone can enhance an advancing trend for the motion of the plate and h er trench retreat. This mechanism provides a novel and alternative explanation for the slow rates of trench migration and fast‐moving plates observed globally at natural subduction zones.
Publisher: American Geophysical Union (AGU)
Date: 12-2014
DOI: 10.1002/2014TC003688
Publisher: American Geophysical Union (AGU)
Date: 12-2022
DOI: 10.1029/2022RG000789
Abstract: Understanding of secular evolution of the Earth system is based largely on the rock and mineral archive preserved in the continental lithosphere. Based on the frequency and range of accessible data preserved in this record, we ide the secular evolution into seven phases: (a) “ Proto‐Earth ” (ca. 4.57–4.45 Ga) (b) “ Primordial Earth ” (ca. 4.45–3.80 Ga) (c) “ Primitive Earth ” (ca. 3.8–3.2 Ga) (d) “Juvenile Earth ” (ca. 3.2–2.5 Ga) (e) “ Youthful Earth ” (ca. 2.5–1.8 Ga) (f) “ Middle Earth ” (ca. 1.8–0.8 Ga) and (g) “ Contemporary Earth ” (since ca. 0.8 Ga). Integrating this record with knowledge of secular cooling of the mantle and lithospheric rheology constrains the changes in the tectonic modes that operated through Earth history. Initial accretion and the Moon forming impact during the Proto‐Earth phase likely resulted in a magma ocean. The solidification of this magma ocean produced the Primordial Earth lithosphere, which preserves evidence for intra‐lithospheric reworking of a rigid lid, but which also likely experienced partial recycling through mantle overturn and meteorite impacts. Evidence for craton formation and stabilization from ca. 3.8 to 2.5 Ga, during the Primitive and Juvenile Earth phases, likely reflects some degree of coupling between the convecting mantle and a lithosphere initially weak enough to favor an internally deformable, squishy‐lid behavior, which led to a transition to more rigid, plate like, behavior by the end of the early Earth phases. The Youthful to Contemporary phases of Earth, all occurred within a plate tectonic framework with changes between phases linked to lithospheric behavior and the supercontinent cycle.
Publisher: Elsevier BV
Date: 03-2010
Publisher: Oxford University Press (OUP)
Date: 06-2006
Publisher: American Geophysical Union (AGU)
Date: 12-10-2022
DOI: 10.1029/2022GL099247
Abstract: The ability to estimate the likelihood of given earthquake magnitudes is critical for seismic hazard assessment. Earthquake magnitude‐recurrence statistics are empirically linked to stress, yet which fault‐zone processes explain this link remains debated. We use numerical models to reproduce the interplay between viscous creep and frictional sliding of a fault‐zone, for which inter‐seismic locking becomes linked to stress. The models reproduce the empirical stress‐dependent earthquake magnitude distribution observed in nature. Stress is related to the likelihood a fault section is near frictional failure, influencing likely rupture lengths. An analytical model is derived of a fault consisting of identical patches, each with a probability of inter‐seismic locking. It reproduces a similar magnitude‐recurrence relationship, which may therefore be caused by probabilistic clustering of locked fault patches. Contrasts in earthquake statistics between regions could therefore be explained by stress variation, which has future potential to further constrain statistical models of regional seismicity.
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-1935
Abstract: & & Rifting in the Afar region is considered to be the only known ex le of the formation of an& incipient ergent triple junction. Taking the Afar region as an ex le, we use three-dimensional& (3D) laboratory experiments to test hypotheses for the formation and evolution& of ergent triple junctions. We systematically evaluate the role of mechanical weakening& due to plume impingement versus inherited weak linear structures in lithospheric mantle& under both far-field orthogonal and rotational extensional boundary conditions. The& interaction between far-field boundary forces and inherited rheological heterogeneities results& in a range of complex rift propagation geometries and structural features, such as rift& segmentation and ridge jumps, which are comparable to those observed in the Afar region.& The combination of rotational boundary conditions and inherited linear heterogeneities& favours the formation of rifts that connect at high-angles. Lithospheric weakening associated with& a mantle plume triggers different rifting styles but has little influence on large-scale& continental breakup. When compared to the Afar region, our results suggest that the rotation& of the Arabian plate since the Oligocene led to rifting of the Red Sea and the Gulf of Aden, which are distinct from the formation of the Main Ethiopian Rift. We suggest that rifting in the Afar region& is not consistent with the incipient ergent triple junction hypothesis. Rather, the Afar triple& junction formed as a result of complex multi-phase rifting events driven by far-field tectonic& forces.& &
Publisher: Proceedings of the National Academy of Sciences
Date: 19-09-2022
Abstract: Continental, orogenic, and oceanic lithospheric mantle embeds sizeable parcels of exotic cratonic lithospheric mantle (CLM) derived from distant, unrelated sources. This hints that CLM recycling into the mantle and its eventual upwelling and relamination at the base of younger plates contribute to the complex structure of the growing lithosphere. Here, we use numerical modeling to investigate the fate and survival of recycled CLM in the ambient mantle and test the viability of CLM relamination under Hadean to present-day mantle temperature conditions and its role in early lithosphere evolution. We show that the foundered CLM is partially mixed and homogenized in the ambient mantle then, as thermal negative buoyancy vanishes, its long-lasting compositional buoyancy drives upwelling, relaminating unrelated growing lithospheric plates and contributing to differentiation under cratonic, orogenic, and oceanic regions. Parts of the CLM remain in the mantle as diffused depleted heterogeneities at multiple scales, which can survive for billions of years. Relamination is maximized for high depletion degrees and mantle temperatures compatible with the early Earth, leading to the upwelling and underplating of large volumes of foundered CLM, a process we name massive regional relamination (MRR). MRR explains the complex source, age, and depletion heterogeneities found in ancient cratonic lithospheric mantle, suggesting this may have been a key component of the construction of continents in the early Earth.
Publisher: Copernicus GmbH
Date: 19-03-2019
Publisher: American Geophysical Union (AGU)
Date: 03-2015
DOI: 10.1002/2014GC005660
Publisher: Geological Society of London
Date: 2011
DOI: 10.1144/SP357.17
Publisher: Geological Society of America
Date: 19-07-2016
DOI: 10.1130/G37912.1
Publisher: American Geophysical Union (AGU)
Date: 11-08-2014
DOI: 10.1002/2013RG000444
Publisher: American Geophysical Union (AGU)
Date: 09-2022
DOI: 10.1029/2022TC007242
Abstract: How seismotectonics of convergent margins reconciles with the force balance of subduction is contentious. The comparison of seismotectonics and available slab pull forces along the Sunda convergent margin shows an enigmatic inverse relationship: upper plate thickening and seismicity magnitude are highest along Sumatra and Andaman, where the slab is shorter than ∼300 km conversely, these are negligible along the Java segment, where the slab reaches deeper, ∼660 km. Using numerical models, we test the role of such slab pull gradients in the force balance of subduction in three‐dimensions, where the slab depth, and therefore its net pull, varies along the trench. We show that in the presence of a “slab step,” the deeper slab drives the convergence of the rigid plate, causing upper plate compression and trench advance in the neighboring trench segments, where a short slab may have no pull to subduct the incoming plate. While neglecting convergence obliquity, the simplified models show relevant along‐trench variations of coupling, trench rotations, and minor strike‐slip shearing due to the slab step, providing a diagnostic strain pattern, with compression/extension atop the short/long slab and minor strike‐slip, increasing in magnitude with depth difference. The modeled tectonic patterns are compared to Sunda margin deformation across scales, from the Cenozoic tectonics to the seismic strain rates, showing remarkable consistency with deformation gradients from Sumatra to Java, potentially illustrating the contribution of the slab step to the seismotectonics of the region.
Publisher: Elsevier BV
Date: 09-2014
Publisher: American Geophysical Union (AGU)
Date: 17-11-2016
DOI: 10.1002/2016GL071186
Publisher: American Geophysical Union (AGU)
Date: 08-2014
DOI: 10.1002/2014JB011163
Publisher: American Geophysical Union (AGU)
Date: 06-2012
DOI: 10.1029/2012GL051988
Publisher: Springer Science and Business Media LLC
Date: 10-01-2010
DOI: 10.1038/NGEO725
Publisher: American Geophysical Union (AGU)
Date: 09-2021
DOI: 10.1029/2020TC006570
Abstract: The collision of continental crust results in the formation of orogenic wedges to accommodate convergence. We use 2D thermomechanical models to address the growth of viscoplastic orogenic wedges, focusing on the structural evolution over time. We find that when the shear stress at the base of the crust is below the yield stress then viscous behavior dictates the evolution, with the wedge structure and geometry influenced by the convergence velocity. In contrast, when the shear stress is equal to or above the yield stress across the entire wedge then plastic behavior controls the evolution, with the structural style and geometry independent of convergence velocity. The models highlight the controls of the basal décollement rheology on the deformation style of the orogenic wedge. We find that for increasing crustal thickness, the velocity required to transition from viscous‐to‐viscoplastic and then to plastic‐dominated wedges increases. We determine empirically how the viscous deformation influences wedge strength and estimate an effective friction coefficient based on the geometry of the entire wedge. The models allow inferences on the dominant deformation mechanism currently accommodating convergence in the Zagros, Himalayas, and European Alps when estimating the effective friction coefficient from the geometry, showing the relevant role of rate‐dependent viscous deformation in each orogenic wedge.
Publisher: Copernicus GmbH
Date: 28-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-9365
Abstract: & & The Red Sea rift exhibits two distinct rifting styles: in the north, the rifting is magma-poor, the crust is hyperextended and the lithospheric necking is asymmetric, in the south, rifting rapidly localized atop a symmetric lithospheric necking. One of the long-standing questions is what drives such different lithospheric necking style? We ran 2D high-resolution thermomechanical numerical simulations of lithospheric rifting to address the northern and southern Red Sea extensional end members and validate the models& #8217 deformation patterns by comparing them against 2D data-driven structural models. The modelling& investigates (a)& the effect of rotational extension by varying extension velocities along the Red Sea, and (b) the thermal structure of the southern Red Sea due to plume impingement, while the& analysis of the outcomes focuses on the early rifting& stage, which involves normal rifting and dike intrusion. We find that asymmetrical lithospheric necking in the central and northern Red Sea is potentially driven by the velocity boundary conditions and inherited structures, mainly the Sirhan rift. The decoupling between the upper portion of the lithosphere and the asymmetrical lithospheric necking, which plays an essential role in the observed deformation patterns in the Arabian margin, is likely controlled by the lower crustal rheology and thickness. Furthermore, we find that the Afar plume near the southern Red Sea, which introduced in our models in form of thermal anomaly, promotes rifting localization.& &
Publisher: Elsevier BV
Date: 11-2023
Publisher: Wiley
Date: 25-09-2020
Publisher: Elsevier BV
Date: 11-2019
Publisher: American Geophysical Union (AGU)
Date: 04-2022
DOI: 10.1029/2021JB023911
Abstract: How the geological record of cratons reconciles with the tectonic environments in which they formed has remained debated. We use 2D Cartesian geometry numerical models of mantle convection varying temperatures from present day to Archaean‐inferred values, to address the formation of cratons, accounting for melt depletion‐dependent rheological stiffening. For mantle temperatures comparable to present day, melting is negligible and the convective regime depends on the strength of the thermal lithosphere. For mantle potential temperatures higher than present day, high depletion degree and large depleted mantle volumes are formed at low lithospheric strength and high surface mobility, whereas these are negligible beneath a poorly mobile lithosphere. When compared to the models, the record of tectonics and large volumes of high‐degree depleted mantle in Archaean cratons is best explained by a lithosphere initially prone to yielding and mobility. At high mobility, large depletion favors the progressive differentiation of the thermochemical lithosphere, which stiffens and thickens with increasing mantle temperatures. The ensuing reduced heat flow atop a hotter mantle is in agreement with the inferred Archaean thermal evolution, and may rule out the viability of a stagnant lid for the early Earth. Large‐scale depletion stiffening resists plate margin formation and this wanes as heat production decreases, thus may hold the key for the establishment of plate tectonics during secular cooling.
Publisher: American Geophysical Union (AGU)
Date: 29-01-2020
DOI: 10.1029/2019GC008649
Publisher: Copernicus GmbH
Date: 03-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-2322
Abstract: & & The largest and most devastating earthquakes on Earth occur along subduction zones. Here, long-term plate motions are accommodated in cycles of strain accumulation and release. Episodic strain release occurs by mechanisms ranging from rapid earthquakes to slow-slip and quasi-static creep along the plate interface. Slip styles can vary between and within subduction zones, though it is unclear what controls margin-scale variability. Current approaches to seismo-tectonics primarily relate the stress state and seismogenesis at subduction margins to interface material properties and plate kinematics, constrained by recorded seismic slip, GPS motions and integrated strain. At larger spatio-temporal scales, significant progress has been made towards the understanding of subduction dynamics and emerging self-consistent plate motions, tectonics and stress coupling at plate margins. The margin stress state is ultimately linked to the force balance arising from interactions between the slab, mantle flow and upper plate. These mantle and lithosphere dynamics are thus expected to govern the tectonic regimes under which seismicity occurs. It remains unclear how these longer- and shorter-term perspectives can be reconciled. We review the aspects of large-scale subduction dynamics that control tectonic loading at plate margins, discuss possible influences on the stress state of the plate interface, and summarise recent advances in integrating the earthquake cycle and large-scale dynamics. It is plausible that variations in large-scale subduction dynamics could systematically influence seismicity, though it remains unclear to what degree this interplay occurs directly through the plate interface stress state and/or indirectly, corresponding to variation of other subduction zone characteristics. While further constraints of the geodynamic controls on the nature of the plate interface and their incorporation into probabilistic earthquake models is required, their ongoing development holds promise for an improved understanding of the global variation of large earthquake occurrence and their associated risk.& &
Start Date: 07-2009
End Date: 01-2015
Amount: $255,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2013
End Date: 12-2017
Amount: $375,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 07-2017
End Date: 12-2024
Amount: $822,800.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2011
End Date: 12-2013
Amount: $200,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2022
End Date: 06-2025
Amount: $423,961.00
Funder: Australian Research Council
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