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