Project

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The thermo-chemical structure of Earth's mantle from joint analysis of seismic and electromagnetic sounding data and thermodynamic modeling

Applicant Khan Amir
Number 159907
Funding scheme Project funding
Research institution Institut für Geophysik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Geophysics
Start/End 01.10.2015 - 30.09.2019
Approved amount 242'552.00
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All Disciplines (5)

Discipline
Geophysics
Mineralogy
Geology
Geochemistry
Other disciplines of Earth Sciences

Keywords (9)

Conductivity; Seismology; Composition; Structure; Petrology; Electromagnetism; Elasticity; Temperature; Mantle

Lay Summary (German)

Lead
Knowledge of the internal constitution of the planets is crucial to our understanding of the origin and evolution of our solar system. The largest insights into the physical structure of the Earth have come from geophysical analyses, and seismology in particular. However, as seismology and geophysical disciplines, in general, are only an indirect means of obtaining information on the fundamental parameters (composition and geotherm), combining seismic velocity models with results and data from laboratory measurements including geochemical analyses of primitive meteorites, mantle xenoliths and mantle-derived magmas, has gained considerably in importance.
Lay summary

The thermo-chemical structure of Earth's mantle from joint analysis of seismic and electromagnetic sounding data and thermodynamic modeling

Inhalt und Ziel des Forschungsprojekts

Kenntnis des inneren Aufbaus der Planeten ist entscheidend für das Verständnis des 
Ursprungs und die Entwicklung unseres Sonnensystems. Die größten Einblicke in die 
physikalische Struktur der Erde stammen von geophysikalischen Analysen 

und Seismologie insbesondere. Weil aber Seismologi und geophysikalischen Disziplinen, 

in der Regel nur ein indirektes Mittel zur Informationsbeschaffung über die 
Grundparameter wie Zusammensetzung sind, haben Methoden die seismischen 

Geschwindigkeitsmodelle mit Ergebnissen und Daten aus Labormessungen einschließlich  

geochemischer Analysen der primitiven Meteoriten und Mantelgesteine kombiniren

erheblich an Bedeutung gewonnen.

 

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts

Eine grundlegende Frage in der heutigen Geowissenschaft betrifft die Bausteine 

??der terrestrischen Planeten unseres Sonnensystems. Die Zusammensetzung von Gesteinen 

aus dem oberen Erdmantel und damit möglicherweise repräsentativ seiner Zusammensetzung 

sind in bezug auf das Element Si im vergleich mit dem primitiven Material (Chondriten),

aus der die terrestrischen Planeten entstanden sind, verarmt. Ein moeglicher Vorschlag

um die Verarmung von Si im Mantel zu erklaeren, laeuft darauf hinaus, dass Si  

im Erdkern und/oder im unteren Mantel der Erde abgelagert hat. Die Auflösung der 

Zusammensetzung des Si-Gehalts des unteren Erdmantels oder der Zusammensetzung der 

Erde im allgemeinen, ist deshalb sehr wichtig und hält zudem das Potential uns 

einen Einblick in die Natur des Materials aus dem die Erde geschaffen ist zu gewaehren.

 

Keywords
Direct link to Lay Summary Last update: 09.10.2015

Responsible applicant and co-applicants

Employees

Publications

Publication
A spectral element approach to computing normal modes
Kemper J, van Driel M, Munch F, Khan A, Giardini D (2022), A spectral element approach to computing normal modes, in Geophysical Journal International, 229(2), 915-932.
Multifrequency Inversion of Ps and Sp Receiver Functions: Methodology and Application to USArray Data
Bissig Felix, Khan Amir, Tauzin Benoit, Sossi Paolo A., Munch Federico D., Giardini Domenico (2021), Multifrequency Inversion of Ps and Sp Receiver Functions: Methodology and Application to USArray Data, in Journal of Geophysical Research: Solid Earth, 126(2), 126.
Seismological evidence for thermo-chemical heterogeneity in Earth's continental mantle
Munch Federico D., Khan Amir, Tauzin Benoit, van Driel Martin, Giardini Domenico (2020), Seismological evidence for thermo-chemical heterogeneity in Earth's continental mantle, in Earth and Planetary Science Letters, 539, 116240-116240.
Joint Inversion of Daily and Long‐Period Geomagnetic Transfer Functions Reveals Lateral Variations in Mantle Water Content
Munch F. D., Grayver A. V., Guzavina M., Kuvshinov A. V., Khan A. (2020), Joint Inversion of Daily and Long‐Period Geomagnetic Transfer Functions Reveals Lateral Variations in Mantle Water Content, in Geophysical Research Letters, 47(10), 539.
Stochastic inversion of geomagnetic observatory data including rigorous treatment of the ocean induction effect with implications for transition zone water content and thermal structure
MunchFederico (2018), Stochastic inversion of geomagnetic observatory data including rigorous treatment of the ocean induction effect with implications for transition zone water content and thermal structure, in Journal of Geophysical Research, 123.
Stochastic inversion of P-to-S converted waves for mantle composition and thermal structure: methodology and application
MunchFederico (2018), Stochastic inversion of P-to-S converted waves for mantle composition and thermal structure: methodology and application, in Journal of Geophysical Research, 123.

Collaboration

Group / person Country
Types of collaboration
Institute of Geochemistry and Petrology, ETHZ Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Communication with the public

Communication Title Media Place Year
Media relations: print media, online media Globally Variable Water Content in the Mantle Transition Zone EOS International 2020

Awards

Title Year
Outstanding Student Presentation Award (OSPA) awarded by the American Geophysical Union (AGU). 2018

Abstract

Knowledge of the internal constitution of the planets is crucial to our understanding of the origin and evolution of our solar system. Global seismic tomography has provided spectacular images of Earth's interior and done much to enhance our understanding of deep Earth processes. These images reveal mantle heterogeneities to exist at several length-scales (from continental to sub-regional and smaller) in the form of lateral variations in density and elastic properties that are believed to be due to thermal and compositional variations. In addition a plethora of slabs have been imaged some of which appear to descend into the lower mantle fueling debate over the large-scale compositional homogeneity of Earth's mantle and its dynamical evolution. Of related importance is the central role played bywater in determining the evolution of Earth through its influence on processes such as chemical differentiation and mantle dynamics. Understanding the deep water cycle and its relation to geodynamics hinges crucially on characterizing these reservoirs as accurately as possible, which, however, due to lack of data is currently limited. Despite an increasing amount of observations and models, the nature and origin of mantle heterogeneities and their implications are still debated.The aim of this project is to directly infer, on a regional and global scale, Earth's mantle composition (major element), thermal state, and water content using several different geophysical data sets (seismic surface-wave data and electromagnetic response functions) that sense different physical rock properties. By combining these data with mantle mineral phase equilibria computations based on a thermodynamic formulation, an expanded database of laboratory conductivity measurements, and a stochastic sampling algorithm we invert directly for the thermo-chemical make-up of Earth's mantle. Due to the fundamental nature of the parameters in question and the adherence to a thermodynamic formulation that link material properties, thermo-chemical parameters and geophysical observables, the approach provides a natural way of integrating widely different data sets. This serves to provide direct as well as tighter constraints on the internal thermo-chemical structure of the Earth than possible with more traditional means.
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