Paul J. Tackley

Paul J. Tackley
ETH Zurich | ETH Zürich · Institute of Geophysics

Doctor of Philosophy

About

298
Publications
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10,259
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Publications

Publications (298)
Article
Full-text available
The timing of the onset of plate tectonics on Earth remains a topic of strong debate, as does the tectonic mode that preceded modern plate tectonics. Understanding possible tectonic modes and transitions between them is also important for other terrestrial planets such as Venus and rocky exoplanets. Recent two-dimensional modelling studies have dem...
Article
Full-text available
The recently adopted Ariel ESA mission will measure the atmospheric composition of a large number of exoplanets. This information will then be used to better constrain planetary bulk compositions. While the connection between the composition of a planetary atmosphere and the bulk interior is still being investigated, the combination of the atmosphe...
Article
Full-text available
The influence of composition-dependent thermal conductivity and heterogeneous internal heating of primordial dense material on the long-term evolution of primordial reservoirs in the lower mantle of the Earth is investigated utilizing thermochemical mantle convection simulations in a 2-D spherical annulus geometry. Our results show that a reduction...
Preprint
Full-text available
The timing of the onset of plate tectonics on Earth remains a topic of strong debate, as does the tectonic mode that preceded modern plate tectonics. Understanding possible tectonic modes and transitions between them is also important for other terrestrial planets such as Venus and rocky exoplanets. Recent two-dimensional modelling studies have dem...
Conference Paper
Although Venus shares many similar characteristics with Earth, like its size, distance to sun, and bulk composition, its surface characteristics significantly differ from those on Earth, especially in the lack of plate tectonics. From a geodynamic perspective, Venus has been proposed to be in an episodic-lid regime with catastrophic resurfacing and...
Preprint
Full-text available
The nature of compositional heterogeneity in Earth’s lower mantle remains a long-standing puzzle that can inform about the long-term thermochemical evolution and dynamics of our planet. Here, we use global-scale 2D models of thermo- chemical mantle convection to investigate the coupled evolution and mixing of (intrinsically-dense) recycled and (int...
Article
Full-text available
The presence of offsets, appearing at intervals ranging from 10s to 100s of kilometres, is a distinct characteristic of constructive tectonic plate margins. By comparison, boundaries associated with subduction exhibit uninterrupted continuity. Here, we present global mantle convection calculations that result in a mobile lithosphere featuring dynam...
Article
Full-text available
The history of the Hawaiian hotspot is of enduring interest in studies of plate motion and mantle flow, and has been investigated by many using the detailed history of the Hawaiian-Emperor Seamount chain. One of the unexplained aspects of this history is the apparent offset of several Emperor seamounts from the Hawaii plume track. Here we show that...
Preprint
Full-text available
The recently adopted Ariel ESA mission will measure the atmospheric composition of a large number of exoplanets. This information will then be used to better constrain planetary bulk compositions. While the connection between the composition of a planetary atmosphere and the bulk interior is still being investigated, the combination of the atmosphe...
Preprint
Full-text available
The tectonic regime of rocky planets fundamentally influences their long-term evolution and cycling of volatiles between interior and atmosphere. Earth is the only known planet with active plate tectonics, but observations of exoplanets may deliver insights into the diversity of tectonic regimes beyond the solar system. Observations of the thermal...
Article
Full-text available
After accretion and formation, terrestrial planets go through at least one magma ocean episode. As the magma ocean crystallises, it creates the first layer of solid rocky mantle. Two different scenarios of magma ocean crystallisation involve that the solid mantle either (1) first appears at the core–mantle boundary and grows upwards or (2) appears...
Article
An important measure of the strength of a mantle plume is its buoyancy flux B, defined as the integral over a horizontal plane of the product of the vertical velocity and the density deficit within the plume. In the case of the Iceland plume, which currently rises directly beneath the mid-Atlantic ridge, published estimates of B cover a range of a...
Conference Paper
Full-text available
The nature of compositional heterogeneity in Earth's lower mantle is a long-standing puzzle that can inform about the long-term thermochemical evolution and dynamics of our planet. On relatively small scales (<1km), the concept of a "marble cake" mantle has gained wide acceptance, emphasizing that streaks of recycled oceanic crust (ROC) and lithosp...
Conference Paper
Full-text available
Rocks in the Earth's interior consist of different mineralogical phases with different rheological properties. In Earth's lower mantle, the main rock constituents are bridgmanite (Br) and smaller amounts of ferropericlase (Fp). Bridgmanite is substantially stronger than ferropericlase, and lower mantle rheology may be highly dependent on the relati...
Article
Aims. The secondary atmospheres of terrestrial planets form and evolve as a consequence of interaction with the interior over geological time. We aim to quantify the influence of planetary bulk composition on the interior–atmosphere evolution for Earth-sized terrestrial planets to aid in the interpretation of future observations of terrestrial exop...
Preprint
Aims: The secondary atmospheres of terrestrial planets form and evolve as a consequence of interaction with the interior over geological time. We aim to quantify the influence of planetary bulk composition on interior--atmosphere evolution to aid the interpretation of future observations of terrestrial exoplanet atmospheres. Methods: We use a geoch...
Conference Paper
Despite stirring by vigorous convection over billions of years, the Earth’s lower mantle appears to be heterogeneous on various length scales. On scales <1km, the concept of a “marble cake” mantle has gained wide acceptance, emphasizing that streaks of recycled oceanic crust (ROC) and lithosphere make up much of the mantle. On larger scales (10s-10...
Article
Full-text available
Seismic studies show two antipodal regions of lower shear velocity at the core–mantle boundary (CMB) called large low-shear-velocity provinces (LLSVPs). They are thought to be thermally and chemically distinct and therefore might have a different density and viscosity than the ambient mantle. Employing a composite rheology, using both diffusion and...
Conference Paper
Full-text available
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 ar...
Preprint
Full-text available
Abstract. After accretion and formation, terrestrial planets go through at least one magma ocean episode. As the magma ocean crystallises, it creates the first layer of solid rocky mantle. Two different scenarios of magma ocean crystallisation involve that the solid mantle either (1) first appears at the core-mantle boundary and grows upwards, or (...
Article
Full-text available
The evolution of the system Earth is critically influenced by the long-term dynamics, composition and structure of the mantle. While cosmochemical and geochemical constraints indicate that the lower mantle hosts an ancient primordial reservoir that may be enriched in SiO2 with respect to the upper mantle, geophysical observations and models point t...
Preprint
The evolution of the system Earth is critically influenced by the long-term dynamics, composition and structure of the mantle. While cosmochemical and geochemical constraints indicate that the lower mantle hosts an ancient primordial reservoir that may be enriched in SiO2 with respect to the upper mantle, geophysical observations and models point t...
Article
The thermal and chemical evolution of rocky planets is controlled by their surface tectonics and magmatic processes. On Earth, magmatism is dominated by plutonism/intrusion versus volcanism/extrusion. However, the role of plutonism on planetary tectonics and long‐term evolution of rocky planets has not been systematically studied. We use numerical...
Article
The presence of a magma ocean may have characterized the beginning of terrestrial planets and, depending on how the solidification has proceeded, the solid mantle may have been in contact with a magma ocean at its upper boundary, its lower boundary, or both, for some period of time. At the interface where the solid is in contact with the liquid the...
Preprint
Full-text available
Abstract. Seismic studies show two antipodal regions of lower shear velocity at the core-mantle boundary (CMB) called Large Low Shear Velocity Provinces (LLSVPs). They are thought to be thermally and chemically distinct, and therefore might have a different density and viscosity than the ambient mantle. Employing a composite rheology, using both di...
Article
The thermo-mechanical evolution of the Earth's mantle is largely controlled by the dynamics of subduction zones, which connect the surface tectonic plates with the interior. However, little is known about the systematics of where subduction initiates and ceases within the framework of global plate motions and evolving continental configurations. He...
Article
Full-text available
Numerical experiments of thermochemical mantle convection in 2‐D spherical annulus geometry are performed to investigate the effects of compositional viscosity ratio (ΔηC) on the long‐term evolution of reservoirs of dense, primordial material in the lowermost mantle of the Earth. The internal heating rate in the primordial material is larger than i...
Preprint
The majority of continental crust formed during the hotter Archean was composed of Tonalite-Trondhjemite-Granodiorite (TTG) rocks. In contrast to the present-day loci of crust formation around subduction zones and intra-plate tectonic settings, TTGs are formed when hydrated basalt melts at garnet-amphibolite, granulite or eclogite facies conditions...
Article
The majority of continental crust formed during the hotter Archean was composed of Tonalite-Trondhjemite-Granodiorite (TTG) rocks. In contrast to the present-day loci of crust formation around subduction zones and intra-plate tectonic settings, TTGs are formed when hydrated basalt melts at garnet-amphibolite, granulite or eclogite facies conditions...
Article
Full-text available
Several authors have suggested that mantle convection is primarily resisted by strong subduction zones, which if true implies small or even negative values of the exponent β in the Nusselt number/Rayleigh number relation Nu ∼ Ra β. To evaluate this hypothesis, we use the boundary element method (BEM) to study the energetics of subduction in a two-d...
Article
Understanding why Earth's lithosphere is divided into several plates while other terrestrial bodies have unbroken lids is a long-standing challenge, often addressed with the help of numerical modelling. A key mechanism defining the transition between these two convective regimes is the formation of shear zones that cut through the entire lithospher...
Article
Continents influence the mantle's convective wavelength and the heat flow escaping from the planet's surface. Over the last few decades, many numerical and analytical studies have contributed to the debate about whether the continents can warm up the subcontinental mantle or not and if they do, then to what extent? However, a consensus regarding th...
Article
Full-text available
Several authors have suggested that mantle convection is primarily resisted by strong subduction zones, which if true implies small or even negative values of the exponent β in the Nusselt number/Rayleigh number relation Nu ∼ Ra^β . To evaluate this hypothesis, we use the boundary element method (BEM) to study the energetics of subduction in a two-...
Article
Experimental and theoretical studies have shown that the iron spin transition alters the properties of lower mantle minerals. This may have important implications for mantle dynamics. In particular, the vigor of convection is enhanced, which in turn may impact the stability of large primordial reservoirs at the base of the lower mantle. Here we per...
Article
Full-text available
The Earth is in a plate tectonics regime with high surface heat flow concentrated at constructive plate boundaries. Other terrestrial bodies that lack plate tectonics are thought to lose their internal heat by conduction through their lids and volcanism: hotter planets (Io and Venus) show widespread volcanism whereas colder ones (modern Mars and Me...
Article
Mantle flow induces dynamic topography at the core-mantle boundary (CMB), with distribution and amplitude that depend on details of the flow. To assess whether observations of CMB topography can give constraints on deep mantle structure, we determine CMB dynamic topography associated with different models of mantle convection, including thermochemi...
Article
Many planetary bodies contain internal liquid layers in their metallic cores or as buried water oceans. Convection in these layers is usually driven by buoyancy sources of thermal or compositional origin, with very different molecular diffusivities. Such conditions can potentially trigger double-diffusive instabilities and fundamentally affect the...
Article
The global geodynamic regime of early Earth, which operated before the onset of plate tectonics, remains contentious. As geological and geochemical data suggest hotter Archean mantle temperature and more intense juvenile magmatism than in the present-day Earth, two crust-mantle interaction modes differing in melt eruption efficiency have been propo...
Article
Full-text available
A key element of plate tectonics on Earth is that the lithosphere is subducting into the mantle. Subduction results from forces that bend and pull the lithosphere into the interior of the Earth. Once subducted, lithospheric slabs are further modified by dynamic forces in the mantle, and their sinking is inhibited by the increase in viscosity of the...
Article
Present thermo-chemical convection models of planetary evolution often assume a purely viscous or visco-plastic rheology. Ignoring elasticity in the cold, outer boundary layer is, however, questionable since elastic effects may play an important role there and affect surface topography as well as the stress distribution within the stiff cold lithos...
Article
Contrasting results on the magnitude of the dynamic component of topography motivate us to analyse the sources of uncertainties affecting long wavelength topography modelling. We obtain a range of mantle density structures from thermo-chemical interpretation of available seismic tomography models. We account for pressure, temperature and compositio...
Article
Full-text available
The theory of plate tectonics describes how the surface of Earth is split into an organized jigsaw of seven large plates of similar sizes and a population of smaller plates whose areas follow a fractal distribution. The reconstruction of global tectonics during the past 200 million years4 suggests that this layout is probably a long- term feature o...
Article
Full-text available
The results of mantle convection simulations are fully determined by the input parameters and boundary conditions used. These input parameters can be for initialisation, such as initial mantle temperature, or can be constant values, such as viscosity exponents. However, knowledge of Earth-like values for many input parameters are very poorly constr...
Preprint
Full-text available
A key element of plate tectonics on Earth is that the lithosphere is subducting into the mantle. Subduction results from forces that bend and pull the lithosphere into the interior of the Earth. Once subducted, lithospheric slabs are further modified by dynamic forces in the mantle and their sinking is inhibited by the increase in viscosity of the...
Article
Full-text available
Within our Solar System, Earth is the only planet to be in a mobile-lid regime. It is generally accepted that the other terrestrial planets are currently in a stagnant-lid regime, with the possible exception of Venus that may be in an episodic-lid regime. In this study, we use numerical simulations to address the question of whether melting-induced...
Article
Full-text available
We perform numerical experiments of thermochemical mantle convection in 2-D spherical annulus geometry to investigate the distribution of post-perovskite (pPv) with respect to the location of primordial reservoirs of dense material in the lowermost mantle. High core-mantle boundary temperatures lead to strong anti-correlation between the locations...
Article
Full-text available
With the progress of mantle convection modelling over the last decade, it now becomes possible to solve for the dynamics of the interior flow and the surface tectonics to first order. We show here that tectonic data (like surface kinematics and seafloor age distribution) and mantle convection models with plate-like behaviour can in principle be com...
Article
We investigate the influence of tectonic mode on the thermo-chemical evolution of simulated mantle convection coupled to a parameterized core cooling model. The tectonic mode is controlled by varying the friction coefficient for brittle behavior, producing the three tectonic modes mobile lid (plate tectonics), stagnant lid and episodic lid. The res...
Article
Full-text available
Numerical simulations of thermal convection in the Earth's mantle often employ a pseudoplas-tic rheology in order to mimic the plate-like behavior of the lithosphere. Yet the benchmark tests available in the literature are largely based on simple linear rheologies in which the viscosity is either assumed to be constant or weakly dependent on temper...
Data
Text S1, Captions of Table S1 and Movie S1, and Figures S1–S4
Article
Full-text available
Numerical simulations of mantle convection with a viscoplastic rheology usually display mobile, episodic or stagnant lid regimes. In this study, we report a new convective regime in which a ridge can form without destabilizing the surrounding lithosphere or forming subduction zones. Using simulations in 2-D spherical annulus geometry, we show that...
Chapter
Full-text available
Seismic tomography indicates that the lowermost mantle, from 2400 km down to the core–mantle boundary (CMB) is strongly heterogeneous at large wavelengths. The most striking features are two large low-shear-wave velocity provinces (LLSVPs), where shear-wave velocity drops by a few percent compared to averaged mantle. Several seismic observations fu...
Poster
Full-text available
EGU 2015 Poster : Reconstructing the 3D structure of the Earth's mantle has been a challenge for geodynamicists for about 40 yr. Although numerical models and computational capabilities have substantially progressed, parameterizations used for modeling convection forced by plate motions are far from being Earth-like. Among the set of parameters, rh...
Conference Paper
Earth's surface topography is controlled by isostatically compensated density variations within the lithosphere, but dynamic topography-i.e. the topography due to adjustment of surface to mantle convection-is an important component, specially at a global scale. In order to separate these two components it is fundamental to estimate crustal and mant...