Paleo-Geodynamics Peculiarities of the Arctic Ocean Eurasian Floor (Earth and Environmental Sciences Library)

The book deals with some issues of paleo-geodynamics of the Eurasian floor of the Arctic Ocean. A comprehensive geological and geophysical analysis of information on the anomalous magnetic field in the Eurasian Basin was carried out using modeling of the inversion magnetically active layer of the oceanic crust. As a result of this analysis, the identification and spatial position of linear paleo-magnetic anomalies were refined, which made it possible to significantly update the geochronology of the bottom of the Eurasian Basin and identify a number of stages in its evolution. On this basis, the features and stages of the kinematics of the development of the bottom of the Eurasian Basin in the past were revealed. At the first Cretaceous–Paleogene stage, prior to the formation of the A26 paleo-anomaly on the Eurasian margin, extension processes developed significantly and turned into rifting. In the process of rifting, weakened zones and related fractures were formed, along which the Siberian continental margin began to be torn off about 60 Ma ago with the formation of the Lomonosov Ridge. At the second stage of evolution, rifting turned into spreading, and the growth rate of the new oceanic crust in the A26–A24 paleo-anomaly interval (59–53 Ma ago) was more than 2.5 cm/yr. At the same time, the northern flank of the Mid-Arctic Ridge grew more intensively than the southern one. The third stage was characterized by a further progressive slowdown in the process of bottom spreading, the minimum of which, with spreading rates of about 1 cm/year, fell on the formation of paleo-anomalies A13-A6 (30-20 million years ago). The fourth stage of growth of the new oceanic crust began later than the time of the A6 paleo-anomaly and is characterized by some intensification of growth at rates up to 1.2 cm/yr. The average rate of bottom growth over an interval of almost 60 Ma turned out to be close to 1.3 cm/yr, which makes it possible to classify the Mid-Arctic Ridge as a slow-growing one. On this basis, kinematic models of the development of bottom configurations were developed with the determination of the Euler poles, rotation angles, asymmetries, axes of spallation and paleo-bathymetry for the Eurasian Basin, the Polar part of the Lomonosov Ridge, the splitting of the Arlis Spura from the Lomonosov Ridge, the development of the Gakkel Ridge and the development of the Greenland region of the bottom. Introduction References Contents About the Authors 1 Geophysical Aspects of Ocean Floor Evolution 1.1 Prerequisites for the Creation of the Concept of Lithospheric Plates 1.2 Discoveries of the 1950s and 1970s in Marine Geology 1.3 Fundamentals of Global Lithospheric Plate Tectonics 1.4 Evolution of the Oceanic Lithosphere 1.5 General Information on the Magnetically Active Layer of the Ocean Floor 1.6 Scale of Linear Magnetic Anomalies of the Ocean Bottom 1.7 Modelling of the Inversion Magnetically Active Layer of the Oceanic Lithosphere References 2 Geochronology of the Eurasian Basin Floor 2.1 Geomorphology of the Seabed 2.2 Identification of Linear Magnetic Anomalies 2.3 Charting the Geochronology of the Seabed 2.4 Conclusions References 3 Paleo-Magnetic Anomalies in the Laptev Sea of the Arctic Ocean References 4 Kinematic Model of the Eurasian Basin Floor Development 4.1 Introduction 4.2 Aeromagnetic Studies 4.3 Geochronology of the Seabed 4.4 Conclusion References 5 Evolution of the Axial Zone of the Mid-Arctic (Gakkel) Ridge in the Upper Neogene References 6 Evolution of Oceanic Crustal Parameters of the Amundsen Basin in the Cenozoic 6.1 Introduction 6.2 Research Results 6.3 Conclusion References 7 Evolution of Oceanic Crustal Parameters of the Nansen Basin in the Cenozoic 7.1 Introduction 7.2 Research Results 7.3 Conclusion References 8 Kinematics of the Polar Area of Lomonosov Ridge Bottom in Arctic 8.1 Introduction 8.2 Research Methodology 8.3 Paleo-Geodynamic Calculation Results 8.4 Conclusion References 9 Kinematic Model of the Arlis Spur Breakaway from the Lomonosov Ridge in the Arctic Ocean 9.1 Introduction 9.2 Peculiarities of Research Methodology 9.3 Research Results 9.4 Conclusion References 10 Kinematic Model of Development of Eastern Areas of the Gakkel Mid-Ocean Ridge in the Eurasian Basin of the Arctic Ocean 10.1 Introduction 10.2 Geological Research 10.3 Structure of the Crust 10.4 Calculation of the Splitting Parameters 10.5 Conclusions References 11 Seafloor Kinematics of the Near-Greenland Region of the Eurasian Basin 11.1 Introduction 11.2 Seafloor Morphology and Deep Water Drilling Data 11.3 Anomalous Gravity Field 11.4 Structure of the Unconsolidated Crust 11.5 Structure of the Acoustic Basement 11.6 Anomalous Magnetic Field 11.7 Discussion 11.8 Calculation of the Splitting Parameters 11.9 Conclusions References Conclusion