Download or read book Constraints on Mantle Convection from Seismic Tomography and Flow Modeling written by Hrafnkell Kárason and published by . This book was released on 2002 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis I combine high resolution seismic tomography and realistic flow modeling to constrain mantle convection. The bulk of the data used in the tomographic imaging are millions of P, pP and pwP travel time residuals, read from high frequency seismic records. The distribution of earthquakes and stations results in uneven data coverage and to improve the model I use core phases (PKP, Pdiff) for the deep mantle and surface reflected phases (PP) for the shallow mantle. Since narrow rays are not adequate for low frequency measurements, I construct broad 3-D sensitivity kernels to relate some of the added data to earth's structure. Furthermore, the parameterization of the tomographic model is adapted to data density and the model shows, among other details, the varying style of subduction in the shallow mantle and complex flow patterns around the transition zone between the upper and lower mantle. I develop a novel and efficient method of modeling buoyancy driven mantle flow in spherical geometry. Here, the linear Stokes equation is solved using a Green's function approach and 3-D surfaces, representing the boundaries of dense material, such as subducting slabs, are tracked through time.
Download or read book Mantle Convection and Surface Expressions written by Hauke Marquardt and published by John Wiley & Sons. This book was released on 2021-07-07 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: A multidisciplinary perspective on the dynamic processes occurring in Earth's mantle The convective motion of material in Earth's mantle, powered by heat from the deep interior of our planet, drives plate tectonics at the surface, generating earthquakes and volcanic activity. It shapes our familiar surface landscapes, and also stabilizes the oceans and atmosphere on geologic timescales. Mantle Convection and Surface Expressions brings together perspectives from observational geophysics, numerical modelling, geochemistry, and mineral physics to build a holistic picture of the deep Earth. It explores the dynamic processes occurring in the mantle as well as the associated heat and material cycles. Volume highlights include: Perspectives from different scientific disciplines with an emphasis on exploring synergies Current state of the mantle, its physical properties, compositional structure, and dynamic evolution Transport of heat and material through the mantle as constrained by geophysical observations, geochemical data and geodynamic model predictions Surface expressions of mantle dynamics and its control on planetary evolution and habitability The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.
Download or read book Global Mantle Convection Models written by Hans-Peter Bunge and published by . This book was released on 1996 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geodynamics of Lithosphere and Earth s Mantle written by Jaroslava Plomerova and published by Springer Science & Business Media. This book was released on 1998-04 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reprint from Pure and Applied Geophysics (PAGEOPH), Volume 151 (1998), No. 2/3/4
Download or read book Treatise on Geophysics written by and published by Elsevier. This book was released on 2015-04-17 with total page 5604 pages. Available in PDF, EPUB and Kindle. Book excerpt: Treatise on Geophysics, Second Edition, is a comprehensive and in-depth study of the physics of the Earth beyond what any geophysics text has provided previously. Thoroughly revised and updated, it provides fundamental and state-of-the-art discussion of all aspects of geophysics. A highlight of the second edition is a new volume on Near Surface Geophysics that discusses the role of geophysics in the exploitation and conservation of natural resources and the assessment of degradation of natural systems by pollution. Additional features include new material in the Planets and Moon, Mantle Dynamics, Core Dynamics, Crustal and Lithosphere Dynamics, Evolution of the Earth, and Geodesy volumes. New material is also presented on the uses of Earth gravity measurements. This title is essential for professionals, researchers, professors, and advanced undergraduate and graduate students in the fields of Geophysics and Earth system science. Comprehensive and detailed coverage of all aspects of geophysics Fundamental and state-of-the-art discussions of all research topics Integration of topics into a coherent whole
Download or read book Characterization of Secondary Mantle Convection from Geophysical Data and Models written by Bimal Pandit and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Small-scale convection or secondary convection has been studied using the geophysical data and models such as seismic tomography models and geoid anomalies. We used three seismic tomography models, SEMUCB-WM1, SAVANI and S40RTS to infer the lithosphere/asthenosphere boundary, and the destabilization of the lithosphere, induced by secondary mantle convection. Former studies, based on numerical and experimental models report that secondary convection would occur as sub-lithospheric longitudinal rolls, induced by the shear associated with the lithospheric plate motion, or as helices, formed when sinking cold plumes, falling from the base of the lithosphere are sheared away by the large-scale flow. Our study shows that the secondary convection under the Pacific plate occurs in the form of 3D plumes and helices. The lithospheric drips observed in the tomography models first appear as small wavelength anomalies beneath a 30-40 M.y. old and 75-90 km thick lithosphere. They are observed as longer elongated patterns beneath 105 M.y. old and 138 km thick lithosphere. Most of the lithospheric anomalies are associated with negative geoid anomalies of order and degrees 8-40. No clear correlation between lithospheric destabilization and volcanism is observed.
Download or read book Modeling Mantle Convection written by David A. Yuen and published by . This book was released on 1996 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Treatise on Geophysics Volume 7 written by David Bercovici and published by Elsevier. This book was released on 2010-05-17 with total page 521 pages. Available in PDF, EPUB and Kindle. Book excerpt: Treatise on Geophysics: Mantle Dynamics, Volume 7 aims to provide both a classical and state-of-the-art introduction to the methods and science of mantle dynamics, as well as survey leading order problems (both solved and unsolved) and current understanding of how the mantle works. It is organized around two themes: (1) how is mantle convection studied; and (2) what do we understand about mantle dynamics to date. The first four chapters are thus concerned with pedagogical reviews of the physics of mantle convection; laboratory studies of the fluid dynamics of convection relevant to the mantle; theoretical analysis of mantle dynamics; and numerical analysis and methods of mantle convection. The subsequent chapters concentrate on leading issues of mantle convection itself, which include the energy budget of the mantle; the upper mantle and lithosphere in and near the spreading center (mid-ocean ridge) environment; the dynamics of subducting slabs; hot spots, melting anomalies, and mantle plumes; and finally, geochemical mantle dynamics and mixing. Self-contained volume starts with an overview of the subject then explores each topic in detail Extensive reference lists and cross references with other volumes to facilitate further research Full-color figures and tables support the text and aid in understanding Content suited for both the expert and non-expert
Download or read book Geodynamics of Lithosphere Earth s Mantle written by Jaroslava Plomerova and published by Birkhäuser. This book was released on 2012-12-06 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plate tectonics has significantly broadened our view of the dynamics of continental evolution, involving both the processes currently active at the surface and those extending deep into the interior of the Earth. Seismic anisotropy provides some of the most diagnostic evidence for mapping past and present deformation of the entire crustmantle system. This volume contains papers presented originally at an international workshop at the Chateau of Trest in the Czech Republic in 1996. This workshop brought together geophysicists and geologists who work in the field of observational and theoretical seismology, mineral and rock physics, gravity studies and geodynamic modelling. Topics include large-scale anisotropy of the Earth's mantle, mantle heterogeneity vs. anisotropy 3-D velocity and density structures and inferences on mantle dynamics, mineral and rock physics studies, and mathematical aspects of complex wave propagation.
Download or read book The Core Mantle Boundary Region written by Michael Gurnis and published by American Geophysical Union. This book was released on 1998-02-04 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: The two giant heat engines responsible for plate tectonics and the geodynamo dynamically interact at the core-mantle boundary of the Earth's interior. A multidisciplinary approach is required to determine the composition, structure, and dynamics of the interface. This volume describes original and fundamental research in seismology, geodynamics, mineral physics, and geomagnetism.
Download or read book Mantle Circulation Models written by Peter Webb and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Mantle circulation models are a modified class of mantle convection simulations assimilating recent plate motions as the surface velocity boundary condition. In this thesis, I present a suite of mantle circulation models assimilating the past 300 million years of tectonic history. By comparing model predictions of present day mantle temperature anomalies to mantle structure imaged by seismic tomography one can better understand the physical properties of Earth's mantle. Given a mantle model with realistic physical properties, plate reconstructions can also be tested. Mantle viscosity is the most significant property affecting mantle circulation models. For subducted slabs to sink to depths predicted by tomography studies a lower mantle viscosity increase of around thirty times is required. For models with a factor of ten increase slabs do not remain at mid-mantle depths for long enough, while a factor of one hundred increase causes slab sinking rates too slow to match imaged tomographic anomalies. An endothermic phase changes could potentially layer mantle convection into two independent layers. In models assimilating plate motions, no model containing an endothermic phase change reaches a fully layered state, even with unrealistically large, negative Clapeyron slopes. The onset of plate tectonics could potentially break down a two-layered mantle into a partially layered state, similar to the present day mantle. Predictions of mantle heterogeneity from high-resolution, global mantle circulation models match well with complex mantle structure imaged by seismic tomography in the Tethys region. These models indicate that a more complicated history of subduction during the closure of the Neotethys Ocean is required to match the imaged mantle structure. Subduction is required in two locations, one at the Eurasian margin and a second behind a back-arc ocean opening in the Neotethys Ocean. Simultaneous subduction at both plate boundaries appears not to be necessary. Global mantle circulation models estimate long-wavelength dynamic topography with amplitudes of up to five kilometres. The largest amplitude signal of dynamic topography is at plate boundaries, suggesting that near surface density variations in the mantle contribute significantly to the dynamic topography signal. The five-kilometre amplitude of topography is larger than predicted elsewhere and is explained by the inclusion of near surface density variations, commonly ignored by other global calculations of dynamic topography. If dynamic topography is defined as 'any topography arising from flow within Earth's mantle' then near surface density variations are significant to the dynamic signal. Predictions of dynamic topography from mantle circulation models reveal a dichotomy between continental and oceanic regions. Oceanic crust is a part of the mantle convection system and so predicted topography for ocean regions matches well with the expected depth versus age curve for oceanic crust. Continental regions are significantly subsided relative to oceans in the dynamic signal, suggesting that isostatic effects mask continental dynamic topography. When predictions of dynamic topography are corrected for isostatic effects and crustal thickness, an accurate estimate of Earth's observed topography is generated. This work contributes to an on going debate on the nature of dynamic topography on global and regional scales.
Download or read book Subduction Zone Geodynamics written by Serge Lallemand and published by Springer Science & Business Media. This book was released on 2009-02-11 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Subduction is a major process that plays a first-order role in the dynamics of the Earth. The sinking of cold lithosphere into the mantle is thought by many authors to be the most important source of energy for plates driving forces. It also deeply modifies the thermal and chemical structure of the mantle, producing arc volcanism and is responsible for the release of most of the seismic energy on Earth. There has been considerable achievements done during the past decades regarding the complex interactions between the various processes acting in subduction zones. This volume contains a collection of contributions that were presented in June 2007 in Montpellier (France) during a conference that gave a state of the art panorama and discussed the perspectives about "Subduction Zone Geodynamics". The papers included in this special volume offer a unique multidisciplinary picture of the recent research on subduction zones geodynamics. They are organized into five main topics: Subduction zone geodynamics, Seismic tomography and anisotropy, Great subduction zone earthquakes, Seismogenic zone characterization, Continental and ridge subduction processes. Each of the 13 papers collected in the present volume is primarily concerned with one of these topics. However, it is important to highlight that papers always treat more than one topic so that all are related lighting on different aspects of the complex and fascinating subduction zones geodynamics.
Download or read book Seismology and Structure of the Earth written by Barbara Romanowicz and published by Elsevier. This book was released on 2010-04-20 with total page 873 pages. Available in PDF, EPUB and Kindle. Book excerpt: Treatise on Geophysics: Seismology and Structure of the Earth, Volume 1, provides a comprehensive review of the state of knowledge on the Earths structure and earthquakes. It addresses various aspects of structural seismology and its applications to other fields of Earth sciences. The book is organized into four parts. The first part principally covers theoretical developments and seismic data analysis techniques from the end of the nineteenth century until the present, with the main emphasis on the development of instrumentation and its deployment. The second part reviews the status of knowledge on the structure of the Earths shallow layers, starting with a global review of the Earth's crustal structure. The third part focuses on the Earth's deep structure, divided into its main units: the upper mantle, the transition zone and upper-mantle discontinuities, the D region at the base of the mantle, and the Earth's core. The fourth part comprises two chapters which discuss constraints on Earth structure from fields other than seismology: mineral physics and geodynamics. Self-contained volume starts with an overview of the subject then explores each topic with in depth detail Extensive reference lists and cross references with other volumes to facilitate further research Full-color figures and tables support the text and aid in understanding Content suited for both the expert and non-expert
Download or read book Investigations Into Aspects of Mantle Viscosity and Dynamics written by Michael A. Ravine and published by . This book was released on 1997 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Seismic Tomography and Mantle Circulation written by Royal Society (Great Britain). Discussion Meeting and published by . This book was released on 1989 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Seismic Tomography written by H.M. Iyer and published by Springer Science & Business Media. This book was released on 1993-05-31 with total page 890 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a systematic review of tomographic applications in seismology and the future directions. Theories and case histories are discussed by the international authors, drawing on their own practical experiences with global and local case histories.
Download or read book Global Full Waveform Tomography Using the Spectral Element Method written by Scott Winfield French and published by . This book was released on 2014 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: The radially anisotropic shear-velocity structure of the earth's mantle provides a critical window on the interior dynamics of the planet, with isotropic variations interpretable in terms of thermal and compositional heterogeneity and anisotropy in terms of flow. Indeed, more than 30 years after the advent of global seismic tomography, many open questions remain regarding the dual roles of temperature and composition in shaping mantle convection, as well as interactions between different dominant scales of convective phenomena. To this end, we use full-waveform inversion of the long-period teleseismic wavefield to image radially anisotropic shear-wave velocity at the scale of the entire globe. In particular, we use a technique which we have termed the "hybrid" waveform-inversion approach, which combines the accuracy and generality of the spectral finite element method (SEM) for forward modeling of the global wavefield, with non-linear asymptotic coupling theory for efficient inverse modeling. This hybrid technique helps considerably in making SEM-based global waveform inversion tractable, as it allows for the use of a rapidly converging Gauss-Newton scheme for optimization of the underlying seismic model. We take additional steps to reduce the cost of these inversions using novel techniques for treatment of the earth's crust. Namely, naive modeling of thinly layered crustal structure can lead to an overly restrictive time-stability condition in the SEM, which in turn drives up the cost these simulations. Instead, taking advantage of the physics of long-period wave propagation, we introduce alternative parameterizations of crustal structure which appear identical to the wavefield, but relax these constraints on stability. We approach this imaging problem in an iterative fashion, hoping to learn something about the earth's interior at each step. First, we present our work focused on the upper mantle and transition zone (≤ 800km depth) in the form of the global model SEMum2, discussing both its development and general properties. Second, we take a detailed look at novel structures in SEMum2 - namely, never-before-seen low-velocity structures in the upper mantle beneath the ocean basins, showing intriguing correlations with other geophysical observables (e.g. absolute plate motions and the geoid). Third, we move on to imaging of the whole mantle, examining the relationships between different scales of convective phenomena in the upper and lower mantle, and particularly those previously seen in SEMum2. Finally, we discuss novel computational aspects of our work, focusing specifically on applications of the partitioned global address-space model of parallel computation to the large-scale data-driven calculations underlying our hybrid inversion approach.
