Project

Discipline

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

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

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Last update: 09.10.2015

Communication	Title	Media	Place	Year

Title	Year

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.