Oceanic Hotspots: Intraplate Submarine Magmatism and Tectonism

ISBN-13: 9783642622908 / Angielski / Miękka / 2012 / 480 str.

Roger Hekinian; Peter Stoffers; Jean-Louis Chemin E.

Opis

Ocean Hotspots provides a comprehensive overview of recent and ongoing research on intraplate volcanism in the ocean basins with special emphasis on the Pacific Ocean. The geology of the seamounts and their associated seamount chains is described, along with detailed geophysical, geochemical and hydrothermal observations made by a multi-disciplinary group of marine geoscientists. These observations lead to a deeper understanding of how the ascending mantle melts, represented by hotspots, are able to penetrate the lithosphere, build seamounts, and enhance hydrothermal circulation. The "fixed" hotspot-generated seamount chains also provide key constraints on plate tectonic reconstructions on the Earth's crust.

Spis treści

References.- 1 Sea-Floor Topography and Morphology of the Superswell Region.- 1.1 Introduction.- 1.2 Data Sources and Methods.- 1.3 Sea-floor Morphology in French Polynesia.- 1.3.1 Bathymetric Expression of the Superswell.- 1.3.2 Midplate Swells.- 1.3.3 Plate Boundary Features.- 1.3.4 Off-Ridge Features.- 1.4 Conclusions.- Acknowledgements.- References.- 2 Seismicity of the Society and Austral Hotspots in the South Pacific: Seismic Detection, Monitoring and Interpretation of Underwater Volcanism.- 2.1 Introduction.- 2.2 Seismic Waves Used.- 2.2.1 Seismic Tremors.- 2.2.2 T Waves.- 2.3 Volcano-Seismic Activities on the Society Hotspot.- 2.3.1 Generalities and Chronological Events.- 2.3.2 The Over-All Seismicity of the Society Hotspot.- 2.3.3 Seismic Detection, Magnitude and Seismic Moment.- 2.3.4 Overview of the Swarms.- 2.3.5 Evolution of the Swarms and Nature of the Recorded Events.- 2.3.6 Frequency-Magnitude Relationship.- 2.3.7 Seismic and Magmatic Activity in the Society Hotspot Volcanoes.- 2.4 Volcano-Seismic Activity of the Austral Hotspot: Macdonald Seamount.- 2.4.1 Seismic Swarms.- 2.4.2 Bathymetric Surveys of the Macdonald Seamount.- 2.5 Summary and Conclusions.- 2.5.1 Society Hotspot.- 2.5.2 Austral Hotspot.- 2.5.3 General Conclusions.- Acknowledgements.- References.- 3 A Global Isostatic Load Model and its Application to Determine the Lithospheric Density Structure of Hotspot Swells.- 3.1 Introduction.- 3.2 Isostasy of the Lithospheric Plate.- 3.2.1 Lithostatic Load.- 3.2.2 The Generalized Equation of Isostatic Load.- 3.3 Reference Model.- 3.3.1 Compensation Depth.- 3.3.2 Lithospheric Density.- 3.3.3 Location of the Reference Column.- 3.4 Lithospheric Density Structure of Hotspot Swells.- 3.4.1 Introduction.- 3.4.2 French Polynesia, South Pacific Super Swell.- 3.4.3 Hawaiian-Emperor Island Chain.- 3.4.4 Mascarene-Réunion Hotspot Track.- 3.4.5 Ascension Island.- 3.4.6 The Great Meteor and Josephine Seamounts.- 3.4.7 Iceland.- 3.5 Subsidence of Hotspot Structures.- 3.6 Conclusions.- Acknowledgements.- References.- 4 Origin of the 43 Ma Bend Along the Hawaiian-Emperor Seamount Chain.- 4.1 Introduction.- 4.2 The Emperor Seamount Chain Paradox.- 4.2.1 Paleomagnetic Interpretations.- 4.2.2 A Simple Test.- 4.2.3 The E-SMC Paradox and Solution.- 4.3 The Origin of the 43Ma Bend.- 4.3.1 Reasoning Towards a Preferred Model.- 4.3.2 “Trench Jam” at 43Ma Caused by the Arrival of Hawaiian Plume Head/Oceanic Plateau.- 4.3.3 Evidence Versus Coincidence.- 4.4 Summary and Conclusion.- Acknowledgements.- References.- 5 South Pacific Intraplate Volcanism: Structure, Morphology and Style of Eruption.- 5.1 Introduction.- 5.2 Society Hotspot.- 5.2.1 Abyssal Hill Region and Limits of Hotspot Vo1canism.- 5.2.2 The Sea Floor (“Bulge”) Around the Hotspot Edifices.- 5.2.3 The Volcanic Edifices of the Society Hotspot.- 5.3 Austral Hotspot.- 5.3.1 The Submarine Edifices of the Austral Hotspot.- 5.4 Pitcairn Hotspot.- 5.4.1 Volcanic Edifices of the Pitcairn Hotspot.- 5.4.2 The Distribution and Extent of Hotspot Volcanism.- 5.5 Hotspot Versus Non-Hotspot Volcanoes.- 5.5.1 Sea-Floor Lineation and Seamount Distribution.- 5.5.2 Morphological Classification of Intraplate Volcanoes.- 5.6 Style of Eruption and Formation of Hotspot Edifices.- 5.6.1 Types of Eruption.- 5.6.2 The Formation of a Volcanic Edifice.- 5.6.3 Relationship Between Hotspot Volcanic Edifices.- 5.7 Summary and Conclusions.- Acknowledgements.- References.- 6 Submarine Landslides in French Polynesia.- 6.1 Introduction.- 6.2 Geological Setting.- 6.2.1 Data.- 6.2.2 Landslide Characterization.- 6.3 Landslides of the Society Islands.- 6.3.1 Mehetia.- 6.3.2 Moua Pihaa Seamount.- 6.3.3 Tahiti.- 6.3.4 Moorea.- 6.3.5 Huahine.- 6.3.6 Raiatea-Tahaa.- 6.3.7 Bora Bora.- 6.3.8 Tupai.- 6.4 Austral Island Landslides.- 6.4.1 Macdonald.- 6.4.2 Rapa.- 6.4.3 Raivavae.- 6.4.4 Tubuai.- 6.4.5 Arago.- 6.4.6 Rurutu.- 6.4.7 Rimatara.- 6.5 Classification of the Society and Austral Landslides.- 6.5.1 Geometric Characteristics.- 6.5.2 Seismic Velocity.- 6.6 Evolution of the Mass Wasting with the Age of the Edifices.- 6.6.1 Landslide Related to Submarine Active Volcanoes.- 6.6.2 Landslide Related to Young Oceanic Islands (4 Ma).- 6.6.4 Landslide Related to Tectonic Events.- 6.7 Conclusion.- Acknowledgements.- References.- 7 Mantle Plumes are NOT From Ancient Oceanic Crust.- 7.1 Introduction.- 7.2 Petrological Arguments.- 7.2.1 Melting of Oceanic Crust Cannot Produce the High Magnesian Melts Parental to Many OIB Suites.- 7.3 Geochemical Arguments.- 7.3.1 Melting of Subduction-Zone Dehydrated Residual Oceanic Crusts Cannot Yield the Trace Element Systematics in OIE.- 7.3.2 OIB Sr-Nd-Hf Isotopes Record no Subduction-Zone Dehydration Signatures.- 7.4 Mineral Physics Arguments.- 7.4.1 Subducted Oceanic Crusts are too Dense to Rise to the Upper Mantle.- 7.4.2 Basaltic Melts in the Lower Mantle Conditions are Denser than Ambient Solid Peridotites.- 7.5 Summary.- Acknowledgements.- References.- 8 The Sources for Hotspot Volcanism in the South Pacific Ocean.- 8.1 Introduction.- 8.2 The Hotspot Chains of the South East Pacific.- 8.2.1 Cook-Australs.- 8.2.2 Society Islands.- 8.2.3 Pitcairn-Gambier Chain.- 8.2.4 Marquesas Islands.- 8.2.5 Juan Fernandez Chain.- 8.2.6 Foundation Seamounts.- 8.2.7 Easter/Sala y Gomez-Nazca Chain.- 8.3 Discussion: Petrogenesis of South East Pacific Hotspots.- 8.3.1 Location of Magma Sources: Plume, Asthenosphere or Lithosphere?.- 8.3.2 Superswell — How Geochemically Different is It?.- Acknowledgements.- References.- 9 Plume-Ridge Interactions: New Perspectives.- 9.1 Introduction.- 9.2 Concepts.- 9.2.1 Mantle Plumes: Deep-Rooted Hot Materials or Wet Shallow Mantle Melting Anomalies?.- 9.2.2 Nature of Plume Materials.- 9.2.3 Ocean Ridges: Ridge Suction — The Active Driving Force for Plume-Ridge Interactions.- 9.2.4 Ridge Suction Increase with Increasing Spreading Rate.- 9.2.5 The Effect of Plume-Ridge Distance.- 9.3 Examples.- 9.3.1 “Proximal” Versus “Distal” Plume-Ridge Interactions.- 9.3.2 Spreading Rate Directs Plume Flows.- 9.4 Summary and Conclusion.- Acknowledgements.- References.- 10 Intraplate Gabbroic Rock Debris Ejected from the Magma Chamber of the Macdonald Seamount (Austral Hotspot): Comparison with Other Provinces.- 10.1 Introduction.- 10.2 The Macdonald Seamount.- 10.2.1 Eruptive Activity.- 10.2.2 Morphology and Structure.- 10.2.3 Sampling and Observations.- 10.2.4 Volcanic Terrains.- 10.3 Petrology.- 10.3.1 Analytical Techniques.- 10.3.2 Rock Descriptions.- 10.4 Geochemistry.- 10.5 Discussion.- 10.5.1 Comparison with Gabbros Recovered from Mid-Ocean Ridges.- 10.5.2 Comparison with Gabbroic Ejecta from Other Intraplate Regions.- 10.5.3 Origin of the Macdonald Seamount Gabbroic Clasts.- 10.6 Summary and Conclusions.- Acknowledgements.- References.- 11 The Foundation Chain: Inferring Hotspot-Plate Interaction from a Weak Seamount Trail.- 11.1 Introduction.- 11.2 Sample Preparation and Analytical Procedure.- 11.2.1 Sample Selection and Preparation.- 11.2.2 Dating Technique.- 11.2.3 Irradiation and Analysis.- 11.2.4 Data Reduction.- 11.3 Results.- 11.3.1 Migration of Volcanism Along the Foundation Chain.- 11.3.2 Hotspot-Spreading Center / Microplate Interaction.- 11.3.3 Volcanic Elongated Ridges (VERs).- 11.4 Discussion.- 11.4.1 VERs and the Pacific-Antarctic Spreading Axis.- 11.4.2 Foundation VERs and the Selkirk Microplate.- 11.4.3 Pacific Plate Motion.- 11.4.4 Implications for Plume-Hotspot Theory.- 11.5 Conclusions.- Acknowledgements.- References.- 12 Hydrothermal Iron and Manganese Crusts from the Pitcairn Hotspot Region.- 12.1 Introduction.- 12.2 Geological Setting.- 12.3 Sample Description.- 12.3.1 Mineralogy.- 12.3.2 Age Dating.- 12.3.3 Biomineralization.- 12.4 Chemical Composition.- 12.4.1 Fe Crusts.- 12.4.2 Mn Crusts.- 12.4.3 Rare Earth Elements (REE).- 12.5 Formation of Fe and Mn Crusts.- 12.6 Conclusions.- Acknowledgements.- References.- 13 Methane Venting into the Water Column Above the Pitcairn and the Society-Austral Seamounts, South Pacific.- 13.1 Introduction.- 13.2 Geological Setting.- 13.3 Methods.- 13.4 Results and Discussion.- 13.4.1 Water Column Characteristics and Methane Distribution.- 13.4.2 Origin of Hydrothermal Methane.- 13.5 Conclusions.- Acknowledgements.- References.- 14 Petrology of Young Submarine Hotspot Lava: Composition and Classification.- 14.1 Introduction.- 14.2 Composition and Description of Oceanic Rocks.- 14.2.1 Common Mineral Constituents.- 14.2.2 Rock Types.- 14.3 Relationship Between Intraplate-Hotspot and Spreading-Ridge Magmatism.- 14.4 Compositional Differences Among Hotspots.- 14.4.1 Relationship between Large and Small Hotspot Edifices.- 14.4.2 Volcanic Stratigraphy.- 14.5 Summary and Conclusions.- Acknowledgements.- References.