Secondary Pyrrhotite as a Recorder of Earth Magnetic Field Variations Dissertation zur Erlangung des Grades eines Doktors der Naturwissenschaften der Geowissenschaftlichen Fakultät der Eberhard-Karls-Universität Tübingen vorgelegt von Florian Wehland aus Mutlangen 2004 Tag der mündlichen Prüfung: 08. Dezember 2004 1. Berichterstatter: Prof. Dr. Erwin Appel, Eberhard-Karls-Universität Tübingen 2. Berichterstatter: Prof.PierreRochette,Université d'Aix-Marseille III 3.Berichterstatter:Prof. John Shaw, Universityof Liverpool „Die Wissenschaft fängt eigentlich erst da an, interessant zu werden, wo sie aufhört“ Justus Freiherr von Liebig (!803-1873), deutscher Chemiker Acknowledgement First of all I like to thank Prof. Erwin Appel and Dr. Viktor Hoffmann for their supervision, the project management, their patience and for the support of my ideas. Dr. Christian Crouzet introduced me in the field of pTRM acquisition and gave a lot of support during field and laboratory work. Prof. Pierre Rochette guidance during my time in France and his final revision of the thesis is greatly acknowledged. Prof. Soffel opened the way for using the magnetic laboratory and supported the development of the TRM furnace at the LMU. Significant contribution to the thesis came from my two diploma students Steffi Braun und Ulrich Alt-Epping.