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Architecture and Geodynamic Evolution of the Svalbard Archipelago, the Yermak Plateau and the Fram Strait Oceanic Province from Deep Seismic Experiments

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Architecture and Geodynamic Evolution of the Svalbard Archipelago, the Yermak Plateau and the Fram Strait Oceanic Province from Deep Seismic Experiments Architecture and geodynamic evolution of the Svalbard Archipelago, the Yermak Plateau and the Fram Strait oceanic Province from deep seismic experiments Aufbau und geodynamische Entwicklungsgeschichte des Svalbard-Archipels, des Yermak Plateaus und der ozeanischen Provinz der Framstraßaus tiefenseismischen Experimenten Oliver Ritzmann Ber. Polarforsch. Meeresforsch. 439 (2003) ISSN 161 8-3193 Oliver Ritzmann Alfred-Wegener-Institut füPolar- und Meeresforschung Geosystem Sektion Struktur und Dynamik der Lithosphär und Polarer Eisschilde Columbusstraß D-27515 Bremerhaven Die vorliegende Arbeit ist die inhaltlich unverändert Fassung einer Dissertation, die im September 2002 dem Fachbereich 5 - Geowissenschaften - der UniversitäBremen vorgelegt wurde. Eine elektronische Version dieser Dissertation kann unter http://www.awi-bremerhaven.de/GPH/dissertationen.html bezogen werden. List of Figures and Tables ...........................................................................................V Abstract .......................................................................................................................vii Kurzfassung................................................................................................................. ix Chapter 1 .......................................................................................................................3 Introduction 1.1 The aim of this thesis .........................................................................................................3 1. 2 Used geophysical methods and the principle of Interpretation ..........................................5 12.1 Seisrnic methods .......................................................................................................5 1.2.2 Potential field methods ..............................................................................................6 1.2.3 Geological interpretation of geophysical data ............................................................6 1.3 Structure of this thesis .......................................................................................................7 Chapter 2 .....................................................................................................................11 Crustal structure of northwestern Svalbard and the adjacent Yermak Plateau: Evidence for Oligocene detachment tectonics and non-volcanic break-up Reprinted from Geophysical Journal International 152. 139.159. Blackwell Science UK. January 2003 2.1 Summary .........................................................................................................................11 2.2 lntroduction ......................................................................................................................11 2.2.1 Geological setting of western Svalbard and the Yermak Plateau ............................13 2.2.2 Offshore geophysical experiments and results ........................................................15 2.2.3 Cenozoic tectonic evolution .....................................................................................16 2.3 Geophysical data .............................................................................................................17 2.3.1 Acquisition of seismic refraction data ......................................................................17 2.3.2 Examples of seisrnic refraction data ........................................................................18 2.3.3 Gravity data .............................................................................................................23 2.4 Velocity modelling ............................................................................................................23 2.4.1 Modelling procedure ................................................................................................23 2.4.2 Final velocity model .................................................................................................25 2.4.3 Resolution and uncertainty of the p-wave velocity model ........................................29 2.5 Gravity rnodelling .............................................................................................................31 2.6 Geologicai interpretation and discussion .........................................................................32 2.6.1 The geology of Segment S1 (Northwestern Svalbard) .............................................32 2.6.2 The geology of segments S2/S3 (Southern Yermak Plateau) .................................35 2.6.3 The geology of segrnent 84 (Central Yermak Plateau) ...........................................38 2.7 Tectonic implications........................................................................................................ 39 2.7.1 The nature and magmatic history of the Yermak Plateau........................................ 39 2.7.2 Cenozoic tectonics between Greenland and Svalbard and subsequent uplift .........42 2.8 Conclusions .....................................................................................................................43 Chapter 3 .....................................................................................................................45 A deep seismic transect in northwestern Svalbard at Kongsfjorden (Ny ~lesund) and the implications for the Cenozoic break-up from Greenland: A sheared margin study Subrnitted to Geophysical Journal International. Blackwell Science UK. September 2002 3.1 Abstract ............................................................................................................................45 3.2 Introduction ......................................................................................................................46 3.2.1 Caledonian geology .................................................................................................46 3.2.2 Tertiary break-up and Western Spitsbergen Fold Belt .............................................49 3.2.3 The deeper structure of Svalbard and the adjacent oceanic province..................... 49 3.3 New geophysical data ......................................................................................................50 3.3.1 Seismic data acquisition ..........................................................................................50 3.3.2 Characteristics of seismic refraction data ................................................................51 3.3.3 2D kinematic raytracing ...........................................................................................56 3.3.4 The final velocity model ...........................................................................................58 3.3.5 Resolution and uncertainty of the final velocity model .............................................60 3.3.6 Gravity data acquisition and characteristics ............................................................63 3.3.7 Gravity modelling .....................................................................................................63 3.3.8 The final density model ............................................................................................65 3.4 Interpretation and discussion ...........................................................................................65 3.4.1 The Cenozoic sedimentary cover east of Molloy Transform Fault ...........................65 3.4.2 The eastern continental section ...............................................................................67 3.4.3 The continent-ocean transition ................................................................................69 3.4.4 The Western oceanic section and Hovggrd Ridge ...................................................71 3.5 The development of the continental margin off Kongsfjorden: A regional view ...............75 3.6 Conclusions .....................................................................................................................77 Chapter 4 ..................................................................................................................... 79 Crustal structure between the Knipovich Ridge and the Van Mijenfjorden (Svalbard) Submitted to Marine Geophysical Researches. Kluwer Acadernic Publishers Netherlands. January 2003 4.1 Abstract ............................................................................................................................79 4.2 Introduction ......................................................................................................................80 4.2.1 Geological and geophysical setting .........................................................................80 4.2.2 Previous deep seismic investigations...................................................................... 82 4.3 New geophysical data ......................................................................................................83 4.3.1 Seismic refraction data - Acquisition ........................................................................83 4.3.2 Seismic refraction data - Processing and Characteristics .......................................83 4.3.3 Seismic reflection data .Acquisition ........................................................................87 4.3.4 Seismic reflection data - Processing and Characteristics ........................................87 4.3.5 Gravity data .............................................................................................................89 iii 4.4 Modelling of refraction
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