Dissertationen online der Freien Universität Berlin
|Haupttitel||A new analytical solution for the calculation of flexural rigidity|
|Titelzusatz||significance and application|
|Titelvariante||Eine neue analytische Lösung zur Berechnung der Biegesteifigkeit|
|Zusatz zur Titelvariante||Bedeutung und Anwendung|
Geburtsort: Jena, Deutschland
|Gutachter||Prof. Hans Jürgen Götze|
|weitere Gutachter||Dr. Nina Kukowski|
Prof. Christoph Heubeck, Prof. Rainer Kind, Prof.
|Freie Schlagwörter||gravity, isostasy, analytical, rigidity, lithosphere|
|Zusammenfassung||In 1939 a new concept was introduced by Vening-Meinesz proposing that the flexural strength of the lithosphere must be considered for isostatic models. A 4th order differential equation describing the flexure of a thin plate was developed. In the past the equation has been solved in frequency space using spectral methods (coherence and admittance). However, the admittance and coherence techniques have been questioned when applied to continental lithosphere. Both methods require an averaging process; therefore the variation in rigidity may be retrieved only to a limited extent. A large spatial window with a side length of at least 375 km is required over the study area. And, in where the input topography is characterized by low topographic variation, the method becomes unstable. These problems can be overcome by calculating the flexural rigidity with the convolution approach and furthermore with the use of a newly derived analytical solution of the differential equation mentioned above. This solution was developed out of three solutions from Hertz and has been made applicable to geological science. The analytical solution has been applied to both oceanic lithosphere (Nazca plate) and continental lithosphere (Central and Patagonian Andes). The resulting flexural rigidity values and their variations have been compared with the ideas and concepts developed by the members of the SFB267 community, and correlate well with tectonic units and fault systems. In the past the elastic thickness has been used synonymously for the flexural rigidity. However, the analytical solution leads to a new interpretation and meaning of the elastic thickness. It is shown that it is sufficient to operate with a constant value for both gravity and Poisson's ratio, as the variation of either parameter does not lead to a significant change in the distribution of flexural rigidity. Young's modulus is shown to be the driving factor for the flexural deformation. A temperature moment must also be taken into account in flexural investigations. Thus, the variation of the elastic thickness can be explained by temperature distribution and a change of the Young's modulus. A new definition of elastic thickness can be obtained: the value of the calculated elastic thickness is equivalent to the value of thickness of a corresponding plate described by a constant Young's modulus. Computations using the differential equation are valid for the crust/mantle interface (Moho) as well as the lithosphere/ asthenosphere boundary. The calculated boundary surface can be shifted at the position of the boundary at which a significant change of Young's modulus takes place.|
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|Tag der Disputation||24.10.2005|
|Erstellt am||30.01.2006 - 00:00:00|
|Letzte Änderung||19.02.2010 - 13:48:26|
|Alte Darwin URL||http://www.diss.fu-berlin.de/2006/42/|
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