Formation of Active Ocean Margins

The ocean floor spreading theory was proposed during 1961 and 62 by Robert Dietz and Harry Hess. This concept was a revolutionary one, and renewed the scientists thoughts on the dynamics of the ocean bottom. Then, for example, the coincidence of the Wadati-Benioff Zone with the subduction zone proposed by new concept was well understood. Further development of the ocean floor spreading theory was the proposal of new concept "plate tectonics" proposed by Xavier LePichon and by a few others during 1967 and 68. This new idea could solve the various conflicts involved in the "ocean floor spreading theory". Therefore, today, scientists understand that the plate tectonics theory was born by the ocean floor spreading theory, which is able to cover the weak points of the latter. D/V Glomar Challenger started her Leg Ion 20 July, 1968 from Orange, Texas to implement the Deep Sea Drilling Project. The timing almost coincided with the proposal period of the plate tectonics. After carrying out a few legs of the drilling operations, the results obtained by D I V Glomar Challenger well proved the rightness of the newly proposed theories of the ocean floor spreading and the plate tectonics. For us, the successful processes started by the ocean floor spreading theory, improved by the concept of plate tectonics and proved by the DSDP results have been a golden monument in the field of earth sciences probably for several centuries.

Contenu
1: Subduction Tectonics.- Pangea, Geoid and the Evolution of the Western Margin of the Pacific Ocean.- Thickness Anomalies of the Lithosphere, Driving Force of Subduction and Accretion Tectonics.- Bending of the Viscoelastic Lithosphere and the Outer Topographic Rise.- Neogene Tectonic Evolution and Plate Subduction in the Japanese Island Arcs.- Two Types of Active Margins: Convergent-Compressional Margins and Convergent-Extensional Margins.- The Age and Mode of Kinematics of the Formation of Forearc Basins and Trench, Japan Trench Region.- 2: Forearc Tectonics.- Kinematics and Mechanics of Deformation Across Some Accreting Forearcs.- Some Implications Regarding Tectonic Mechanisms from the Structural Diversity Along Several Modern Convergent Margins.- Internal Structures of the Accretionary Wedge in the Nankai Trough Off Shikoku, Southwestern Japan.- Sediment Accretion and Subduction in the Middle America Trench.- The Origin of Some Common Types of Melange in the Western Cordillera of North America.- Fore-Arc Tectonics in the Northern Mariana Arc.- Seamarc II Studies of Subducting Seamounts.- Dredged Samples from the Ogasawara Fore-Arc Seamount or Ogasawara PaleolandFore-Arc Ophiolite.- Accretion in the Nankai Trough.- 3: Arc Magmatism.- Arc MagmatismAn Unresolved Problem of Sources, Material Fluxes, Tectonic Evolution and Thermochemical Regions of Subduction Zones.- Geochemical Characteristics of Back-Arc Basin Basalt.- A Miocene Forearc Magmatism at Shionomisaki, Southwest Japan.- Volcanogenic Sediments of the Japan Trench Area and Tertiary Explosive Volcanism of the Tohoku Arc.- On the Episodic Vicissitude of Tectonic Stress Field of the Cenozoic Northeast Honshu Arc, Japan.- 4: Back-Arc Tectonics.- Age of Subducting Lithosphere and Back-Arc Basin Formation in the Western Pacific Since the Middle Tertiary.- Sofugan Tectonic Line, A New Tectonic Boundary Separating Northern and Southern Parts of the Ogasawara (Bonin) Arc, Northwest Pacific.- Regional Geology of the Beringian Continental Margin.- Sedimentation Patterns in Relation to Rifting, Arc Volcanism and Tectonic Uplift in Back-Arc Basin of the Western Pacific Ocean.- When Was the Japan Sea Opened?: Paleomagnetic Evidence from Southwest Japan.- Formation of the Okinawa Trough.- 5: Accretion Tectonics (I).- Tectonic Instability on a Stable Shelf behind a Passive MarginA Structural History of the English Channel.- The Fate of Seamounts and Oceanic Plateaus Encountering a Deep-Sea Trench and Their Effects on the Continental Margins.- 6: Accretion Tectonics (II).- Tectonic Framework of the Kuril Arc Since Its Initiation.- Early Cretaceous Dual Subduction System In and Around the Kamuikotan Tectonic Belt, Hokkaido, Japan.- Influence of Izu Subduction-Collision on the Deformation of Central Japan.- Ophiolite-Based Forearcs: A Particular Type of Plate Boundary.- Broken Seamount Fragments in the Setogawa Subduction Complex.- Paleomagnetic Evidence of the Northward Drift of the Izu Peninsula, Central Japan.- 7: Accretion Tectonics (III).- Some Tectonic and Tectogenetic Aspects of SW Japan: An Alpine-Type Orogen in an Island-Arc Position.- Stratigraphic Change of the Coarse Clastic Rocks of the Shimanto Supergroup in Eastern, Shikoku, Southwest Japan.- Sedimentary Evolution of Shikoku Subduction Zone: The Shimanto Belt and Nankai Trough.- Collision of the Amami Plateau with the Ryukyu Island Arc.- Coral Reefs and Present-Day Collision-Subduction Tectonics.- 8: Pelagic Sediments.- Chemical Compositions of Pelagic Deep-Sea SedimentsIts Relation to the Formation of Authigenic Mineral Phase under the Chemical Control of Sea Water.- Manganese Content, Cerium Anomaly, and Rate of Sedimentation as Aids in the Characterization and Classification of Deep-Sea Sediments.