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The Effect of Eclogitization of Crustal Rocks on the Seismic Properties on Variable Scales: Implications for Geophysical Imaging of Eclogitization at Depth

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The Effect of Eclogitization of Crustal Rocks on the Seismic Properties on Variable Scales: Implications for Geophysical Imaging of Eclogitization at Depth View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Institutional Repository of the Freie Universität Berlin The effect of eclogitization of crustal rocks on the seismic properties on variable scales: Implications for geophysical imaging of eclogitization at depth Dissertation Submitted in Partial Fulfilment of the Requirements for the Degree Doktor der Naturwissenschaften (doctor rerum naturalium) Vorgelegt von: Sascha Heinrich Pablo Zertani Fachbereich Geowissenschaften Freie Universität Berlin Berlin 2019 Gutachter: Prof. Dr. Timm John Prof. Dr. Frederik Tilmann Disputationsdatum: 21. Januar 2020 Erklärung: Hiermit versichere ich die vorliegende Arbeit selbständig verfasst zu haben. Es wurden keine anderen Quellen und Hilfsmittel als die in der Arbeit angegebenen verwendet und alle Ausführungen die anderen Schriften wörtlich oder sinngemäß entnommen wurden sind kenntlich gemacht. Die Arbeit lag bisher weder in gleicher noch in ähnlicher Form einer Prüfungsbehörde vor. Berlin, 2019 iii iv “Geologists have a saying – rocks remember.” Neil Armstrong v vi Table of contents Summary .................................................................................................................................................. ix Zusammenfassung .................................................................................................................................... xi 1 Introduction ...........................................................................................................................................1 1.1 Seismic imaging of eclogitization at depth .................................................................................2 1.2 Eclogitization from a field perspective .......................................................................................5 1.3 Holsnøy as an example for the eclogitization of dry crust ...........................................................6 1.4 Petrophysical properties of the lower crust and eclogites ............................................................7 1.5 The SPP “Mountain building in 4 dimensions” ........................................................................8 1.6 Aim of the thesis .......................................................................................................................9 1.7 Outline of the thesis ..................................................................................................................9 1.8 References ...............................................................................................................................11 2 The interplay of eclogitization and deformation during deep burial of the lower continental crust – A case study from the Bergen Arcs (western Norway) .........................................................................................15 Abstract .........................................................................................................................................16 2.1 Introduction ............................................................................................................................16 2.2 Geological setting ....................................................................................................................18 2.3 Methods ..................................................................................................................................20 2.4 Field relations on Holsnøy ......................................................................................................21 2.5 Discussion ...............................................................................................................................30 2.6 Conclusions ............................................................................................................................35 2.7 Acknowledgments ...................................................................................................................36 2.8 References ...............................................................................................................................36 3 Modification of the seismic properties of subducting continental crust by eclogitization and deformation processes ..................................................................................................................................................43 Abstract .........................................................................................................................................44 3.1 Introduction ............................................................................................................................44 3.2 Geological setting ....................................................................................................................46 3.3 Methods ..................................................................................................................................48 3.4 Sample description ..................................................................................................................49 3.5 Results ....................................................................................................................................53 3.6 Discussion ...............................................................................................................................62 3.7 Conclusions ............................................................................................................................70 Acknowledgements........................................................................................................................71 References .....................................................................................................................................71 vii 4 P wave anisotropy caused by partial eclogitization of subducting crust demonstrated by modelling effective petrophysical properties .......................................................................................................................... 81 Abstract ........................................................................................................................................ 82 4.1 Introduction ........................................................................................................................... 82 4.2 Geological setting ................................................................................................................... 84 4.3 Model setup ........................................................................................................................... 86 4.4 Results .................................................................................................................................... 89 4.5 Discussion .............................................................................................................................. 95 4.6 Conclusions .......................................................................................................................... 100 Acknowledgments ...................................................................................................................... 100 References .................................................................................................................................. 100 5 Conclusions and outlook ................................................................................................................... 107 5.1 Conclusions .......................................................................................................................... 108 5.2 Outlook ................................................................................................................................ 110 Appendix A – Related publications ....................................................................................................... 111 Appendix B – Supporting information of “The interplay of eclogitization and deformation during deep burial of the lower continental crust–A case study from the Bergen Arcs (western Norway)” – Chapter 2 .......................................................................................................................................... 113 Appendix C – Supporting information of “Modification of the seismic properties of subducting continental crust by eclogitization and deformation processes” – Chapter 3 ............................................................ 119 Appendix D – Supporting information of “P wave anisotropy caused by partial eclogitization of subducting crust demonstrated by modelling effective petrophysical properties” – Chapter 4 .................................. 147 Curriculum vitae ................................................................................................................................... 153 Acknowledgments ................................................................................................................................. 155 viii Summary Plate tectonics shapes the face of the earth and subduction and collision zones are among the most important features on Earth. Here, crustal material is recycled into the mantle or integrated into growing orogens. However, the processes active at depth cannot be studied directly and we thus rely on geophysical imaging methods to visualize the geometries that result from the ongoing processes. Additionally, these processes can be studied in fossil
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