Structures of ophiolites and dynamics of oceanic lithosphere
著者
書誌事項
Structures of ophiolites and dynamics of oceanic lithosphere
（Petrology and structural geology, v. 4）
Kluwer Academic Publishers, c1989
大学図書館所蔵 全13件
注記
Bibliography: p. 321-358
Includes index
内容説明・目次
内容説明
1.1. HISTORICAL DEVELOPMENT OF THE OPHIOLITE CONCEPT. Ophiolite, Greek for 'the snake stone', appears to have received its first written definition by Brongniart (1813) as a serpentine matrix containing various minerals. Later in 1821 and 1827, Brongniart determined that volcanic and gabbroic rocks were also present, associated with cherts, and he ascribed an igneous origin to the ophiolite. Amstutz (1980) gives an excellent exegesis of these early contributions and traces the further use of the term and concept of ophiolite. This concept had been forged in the western Alps and Apennines where, thanks to talented Italian geologists, in particular A. Sismonda, B. Gastaldi, V. Novarese and S. Franchi, the study on metamorphic ophiolites (the 'pietre verdi') has rapidly progressed. At the tum of the century the association of radiolarite, diabase, gabbro (euphotide), and serpentinite-peridotite was clearly identified, even through their metamorphic transformations.
In 1902, Franchi developed the hypothesis introduced earlier by Lotti (1886), of a submarine outflow to explain the 'pietre verdi' association, on the basis of the attribution of the variolites and metamorphic prasinites to an hypabyssal volcanism, also responsible for the formation of radiolarites. Thus, before the popular work of Steinmann in 1927, the various components constituting an ophiolite had been identified and its hypabyssal origin proposed. As recalled by Amstutz (1980), the so-called 'Steinmann trinity', which consists of the association of radiolarites, diabases and serpentinites, was more completely and better defined in these earlier works.
目次
I - Introduction and Analytical Methods.- 1. Introduction.- 1.1. Historical development of the ophiolite concept.- 1.2. Interest of ophiolite studies.- 1.2.1. Ophiolites as key for the study of oceanic lithosphere and asthenosphere.- 1.2.2. Ophiolites as markers of past plate tectonics.- 1.3. Scope and structure of the book.- 2. Analytical methods in ophiolites.- 2.1. Introduction.- 2.2. The oceanic reference frame.- 2.2.1. The ridge referential.- 2.2.2. Ridge side of origin of a given ophiolite.- 2.3. Structural studies in the hypovolcanic and volcanic sequences.- 2.4. Structural studies in the plutonic sequence.- 2.4.1. Principal structures.- 2.4.2. Viscous/plastic deformation.- 2.4.3. Importance of viscous flow.- 2.5. Structural studies in the ultramafic section.- 2.5.1. Homogeneity of mantle structures.- 2.5.2. Principal structures.- 2.5.3. Melt products: evidence for segregation/impregnation.- 2.5.4. Microstructures in peridotites and kinematic analysis.- 2.5.5. Microstructural imprint of asthenospheric and lithospheric flow.- 2.5.6. Serpentinization and low temperature deformations.- 2.6. Expected asthenospheric flow patterns.- II - Typical Ophiolite Complexes.- 3. Oman ophiolite: the harzburgite ophiolite type.- 3.1. Introduction.- 3.2. Geological setting.- 3.2.1. Geodynamic setting.- 3.2.2. History of the Hawasina basin.- 3.3. General description of the ophiolite.- 3.3.1. Introduction.- 3.3.2. Mafic section.- 3.3.3. Ultramafic section.- 3.3.4. Metamorphic aureoles.- 3.3.5. High pressure metamorphism.- 3.4. Structure of the Oman ophiolite.- 3.4.1. Introduction-main structural events.- 3.4.2. Structures related to accretion at the spreading center.- 3.4.3. Structures related to oceanic thrusting and obduction.- 3.5. General interpretation of the Oman ophiolite.- 3.5.1. Introduction.- 3.5.2. Spreading rate estimation.- 3.5.3. Paleo-environment of origin and obduction history.- 4. Xigaze and Trinity ophiolites-Plagioclase lherzolite massifs: the lherzolite ophiolite type.- 4.1. Introduction.- 4.2. Xigaze ophiolite.- 4.2.1. Introduction.- 4.2.2. Geological setting.- 4.2.3. Description.- 4.2.4. Structural analysis.- 4.2.5. Geochemistry.- 4.2.6. Discussion.- 4.3. Trinity ophiolite.- 4.3.1. Introduction.- 4.3.2. Geological setting.- 4.3.3. Description.- 4.3.4. Structural analysis.- 4.3.5. Melt extraction and melt reaction.- 4.3.6. Petrology and geochemistry.- 4.3.7. Discussion.- 4.4. The western Alps ophiolites.- 4.5. The spinel-plagioclase lherzolite massifs.- 4.5.1. Penological zonation.- 4.5.2. Structural zonation.- 4.5.3. Structure and geodynamic environment.- 4.5.4. Contact metamorphism and nature of metamorphosed formations.- 5. Bogota Peninsula and N.E. districts of New Caledonia - Wadi Tayin in Oman - Coastal Complex of Newfoundland: possible origin in transform faults.- 5.1. Introduction.- 5.2. Bogota Peninsula and N.E. ophiolitic districts of New-Caledonia.- 5.2.1. Introduction.- 5.2.2. Geological setting.- 5.2.3. Description of the Bogota Peninsula shear zone.- 5.2.4. Description of the Tiebaghi-Poum-Belep shear zone.- 5.2.5. Discussion.- 5.3. Coastal Complex of Newfoundland.- 5.3.1. Introduction.- 5.3.2. Geological setting.- 5.3.3. Description.- 5.3.4. Petrology and geochemistry.- 5.3.5. Interpretation.- 5.4. Wadi Tayin massif in Oman.- 5.4.1. Introduction.- 5.4.2. Structural description.- 5.4.3. Discussion.- 5.5. Conclusion.- 5.5.1. The diversity of ophiolitic transforms.- 5.5.2. Dike orientation in transform zones.- 6. Canyon Mountain ophiolite: possible origin in an island arc.- 6.1. Introduction.- 6.2. Geological setting.- 6.3. Description.- 6.4. Structural analysis.- 6.5. Petrology and geochemistry.- 6.6. Discussion.- 6.6.1. Specific characteristics of the Canyon Mountain ophiolite.- 6.6.2. Structural models.- 6.6.3. Geodynamic environment of origin.- III - Activity of Oceanic Spreading Centers and the Origin of Ophiolites.- 7. Melt generation and extraction in mantle diapers.- 7.1. Introduction.- 7.2. Melt extraction from the asthenosphere.- 7.2.1. Conditions of adiabatic melting.- 7.2.2. Asthenospheric path and the meeting with lithospheric conditions.- 7.2.3. Depth of first melting.- 7.2.4. Maximum depth of melt extraction.- 7.3. Physical mechanisms of melt extraction.- 7.3.1. Fraction of stable melt in a peridotite.- 7.3.2. Melt extraction.- 7.4. A model of melt extraction by hydrofracturing.- 7.4.1. The model.- 7.4.2. Melt velocity within dikes, episodicity and duration of episodes of melt extraction.- 7.4.3. Geochemical implications.- 7.5. Melt extraction by solid compaction and melt percolation in transition zones of ophiolites.- 7.6. Focusing of melt extraction below oceanic ridges.- 8. The various ophiolites and their oceanic environments of origin.- 8.1. Introduction.- 8.2. Harzburgite and lherzolite types of ophiolites - Role of spreading rate.- 8.2.1. Distinctive characteristics.- 8.2.2. Harzburgite and lherzolite types of ophiolites and mantle partial melting.- 8.2.3. Harzburgite and lherzolite types of ophiolites and oceanic environments.- 8.3. Island-arc, back-arc or mid-ocean ophiolites.- 8.3.1. Geochemical characteristics.- 8.3.2. Other criteria.- 9. Mantle flow, tithospheric accretion and segmentation of oceanic ridges.- 9.1. Introduction.- 9.2. Mantle flow in the Oman ophiolite.- 9.2.1. Introduction.- 9.2.2. Homogeneous mantle flow away from the ridge-Relation with seismic anisotropy.- 9.2.3. Channeling of mantle flow along the ridge axis.- 9.2.4. Mantle flow in transform faults.- 9.2.5. Mantle flow in diapers.- 9.2.6. Mantle flow patterns beneath the Oman paleo-ridge.- 9.3. Mantle flow in the Trinity ophiolite and lherzolite massifs.- 9.4. Mantle diapirism and ridge segmentation.- 9.4.1. Introduction.- 9.4.2. Models of mantle diapers.- 9.4.3. Return flow and thickness of the buoyant layer.- 9.4.4. Spacing of mantle diapirs and ridge segmentation.- 9.4.5. Stability of mantle diapers.- 10. Magmatic processes in the uppermost mantle at oceanic spreading centers.- 10.1. Introduction.- 10.2. Principal characteristics of transition zones.- 10.3. Origin of the wehrlitic intrusions.- 10.4. Origin of dunites.- 10.4.1. Introduction.- 10.4.2. Field occurrences.- 10.4.3. Residual/magmatic origin.- 10.4.4. Mechanism of formation of residual dunites.- 10.4.5. Geochemical reequilibration.- 10.4.6. Conclusion as to the origin of dunites.- 10.5. Structure and origin of the chromite deposits.- 10.5.1. Introduction.- 10.5.2. Setting of chromite deposits.- 10.5.3. Structure of chromite deposits.- 10.5.4. Composition of chromite deposits.- 10.5.5. Origin of chromite deposits.- 11 - Generation of oceanic crust.- 11.1. Introduction.- 11.2. Lithology of ophiolites and seismic structure of the oceanic crust.- 11.3. Serpentinite sea-floor in slow spreading environments and LOT.- 11.3.1.Abyssal and ophiolitic peridotites.- 11.3.2. Serpentinized peridotites as sea-floor.- 11.3.3. Nature of the Moho.- 11.4. The plutonic section and the problem of magma chambers.- 11.4.1. Introduction.- 11.4.2. Origin of the layering in the plutonic gabbro sequence.- 11.4.3. Magma chamber models.- 11.4.4. Conclusions about magma chamber models.- 11.4.5. Plating of gabbros and diking at the roof of magma chambers.- 11.4.6. Initiation of a new magma chamber.- 11.5. Sheeted dikes and volcanic units.- 11.5.1. Introduction.- 11.5.2. Generation at rifts and ridges.- 11.5.3. Structural evolution of the volcanic-hypovolcanic units.- 11.6. Crustal discontinuities in lherzolite type of ophiolite and episodic oceanic spreading.- 11.6.1. Variable basalt delivery along ridge-strike.- 11.6.2. Episodic basalt delivery in time.- 11.7. Early metamorphism in ophiolites and hydrothermal activity at oceanic ridges.- 11.7.1. Introduction.- 11.7.2. Metamorphic-zonation in ophiolites.- 11.7.3. Relationship with the sequence of hydrothermal alteration in oceanic crust.- IV - Emplacement of Ophiolites Trough Space and Time.- 12 - Ophiolites emplacement.- 12.1. Introduction.- 12.2. Ophiolite belts.- 12.2.1. Passive margins of continents.- 12.2.2. Active margins of continents.- 12.2.3. Collision belts.- 12.3. Emplacement-related features in ophiolites.- 12.3.1. Introduction.- 12.3.2. Ophiolite nappes and high temperature aureoles.- 12.3.3. Ophiolitic melanges and high pressure metamorphism.- 12.4. Mechanisms of ophiolite emplacement.- 12.4.1. Introduction.- 12.4.2. Thrusting on passive continental margins.- 12.4.3. Upheaval in the accretionary prism of active margins.- 12.5. Summary and concluding remarks.- 13 - Ophiolite belts through time.- 13.1. Introduction: a reappraisal of ophiolites and their oceanic environments.- 13.2. Ophiolites generation and emplacement through time.- 13.3. Ophiolites as witness of pangean cycles.
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