Determination of Structural Successions in Migmatites and Gneisses

This is the first book to deal specifically with the procedures used in the analysis of structural relationships and the determination of structural successions in complexly deformed rocks such as migmatites and gneisses. The establishment of structural successions enables: The rigorous control of the dating of specific events in the deformational history by constraining the sites of the dated rocks within the structural succession; The establishment of the time span of orogenic events throughout the structural succession, and the rate of orogenic processes;Their comparison to be used as a basis for correlation between dismembered and separated crustal segments in continental reconstructions;The resolution of the complex relationships between deformed ore bodies and host rocks in high grade terranes, and hence determination of the structural control of ore bodies, an essential part of any successful geological exploration, and a precondition to efficient exploitation. With its new approach, and the use of practical field examples from various parts of the world, this highly illustrated work will form an invaluable reference resource for postgraduates, lecturers and researchers in the structural and isotope geology of high-grade metamorphic terranes, as well as for exploration and survey geologists working in the field.

Dr Alaric M. Hopgood who holds an Honorary Readership at the University of St Andrews, Scotland, was a Reader in the Department of Geology there until 1995.

Contenu
1 General Characteristics of Migmatites and Migmatite Terranes.- 1.1 Introduction.- 2 Principles of Structural Analysis of Migmatites.- 2.1 Complex Structures Considered as Components of a Succession.- 2.2 Resolving Structural Complexity in Migmatites.- 2.3 Assumptions Inherent in the Approach Used.- 3 Development of Migmatite Structure: Overprinting.- 3.1 Overprinting.- 3.2 Departures from Consistent Overprinted Structure Patterns.- 4 The Role of Structures Interposed in the Succession.- 4.1 The Significance of Geometrically Simple Structures Imposed on the Developing Succession.- 4.2 Behaviour of Simple (Planar) Structures During Deformation.- 4.3 Illustrations of the Importance of Simple Interposed Structures in Resolving (Structural) Successions.- 5 Fold (Structure) Successions and Deformational Sequences.- 5.1 Successions and Sequences.- 5.2 Identification, Recognition and Classification of Structures.- 5.3 Fold (Structure) Sets.- 6 Correlation.- 6.1 Principles and Basis of Correlation.- 6.2 Style, its Significance and Factors Influencing it.- 6.3 Key Structures.- 7 Characteristic Features of Structure Successions.- 7.1 General Features of Fold Successions.- 7.2 Illustrations of Temporal Changes of Style in Fold Successions.- 7.3 Summary of Principal Features of Fold Successions.- 7.4 Variation with time of Total Structural Complexity.- 7.5 Paradox of Apparent Similarity of Fold Successions.- 7.6 Examples Illustrating the Superficial Similarity of Fold Successions.- 7.7 Summary of Fold Variation in Successions.- 8 Principles of Succession Determination.- 8.1 Determining the Structural Succession: Theory.- 9 Field Approach: Reconnaissance and Detailed Study.- 9.1 Introduction.- 9.2 Field Procedures.- 10 Structural Observation.- 10.1 Observation of Structures and Structural Relationships.- 11 Examples of Complex Structural Relationships.- 11.1 Local Structure Successions Comprising Several Sets.- 12 Principles and Practice of Determining Structural Successions Summarized.- 12.1 Introduction.- 12.2 Observation.- 12.3 Identification of Structures.- 12.4 Key Structures.- 12.5 Correlation - Discussion of Principles.- 12.6 Integration of Local Successions - Discussion of Principles.- 13 Analytical Procedure Summarized.- 13.1 Introduction.- 13.2 Correlating Local Sub-Successions: Formal Procedure.- 13.3 Illustrations of Procedure.- 13.4 Application of Procedure - Examples from Different Settings.- 14 Broad Applications.- 14.1 Academic Applications.- 14.2 Economic Applications.- 14.3 Summary.- 15 Conclusions.- 15.1 Concluding Remarks.- 15.2 Postscript: Some Points to Bear in Mind.- References.- Author Index.- Locality Index.