Microtextures of Igneous and Metamorphic Rocks

About this book

At a time when 'textural' evidence is regarded as being 'obvious', it becomes more and more difficult to find illustrations or even descriptions of the arrangements of the various constituents of 'traumatized' rocks. It is helpful in consequence to advise geology students that the study of thin sections is not only concerned with the identification of their mineral content. To do so would mean they could not see the wood for the trees. Accurate identification of the indi­vidual minerals that form rocks is fundamental in their description but the analysis of their textures and habits is also essential. Study of textural features enforces constraints upon the inter­pretation of the origin and history of a rock. The analysis of micro­ textures cannot and should never be an aim in itself, but must be sup­ported by qualitative and quantitative correlations with theories of petrogenesis. The aim here is to help the reader to bridge the gap between his observations of rocks under the microscope and petrogenetic theories. The habits or architectures of crystals in rocks may resemble those studied by metallurgists and glass scientists. Analysis of micro­ textures is undergoing change engendered by comparisons between manu­factured and hence minerals. This can be seen from the increased number of publications dealing with crystal grrowth or deformation processes at microscopic scales to which the name of 'nanotectonics' has been applied.

Contents

I: Nucleation and Crystal Growth
1 / Nucleation Theories
      1.1. Homogeneous Nucleation
      1.2. Heterogeneous Nucleation
      1.3. Sites of Heterogeneous Nucleation
            1.3.1. Crystal Defects
            1.3.2. Grain Boundaries
2 / Theories of Crystal Growth
      2.1. Dendritic Growth
      2.2. 'Layer by Layer' Growth
      2.3. Spiral Growth
      2.4. Other Mechanism of Crystal Growth
            2.4.1. 'Vertex-edge' Growth
            2.4.2. Growth on a Twin Plane
      2.5. Mass Transfer Phenoma
            2.5.1. Liquid?solid Transformations
            2.5.2. Solid?solid Transformations
      2.6. Crystal Form and Size
      2.6.1 Crystal Form
      2.6.2. Crystal Size

II: Order of Crystallization in Igneous and Metamorphic Rocks
3 / General Chronological Criteria
4 / Orders of Crystallization in Igneous Rocks
      4.1. Textures of Binary Systems Subjected to Eutectic Reactions
      4.2. Textures of Binary Systems Subjected to Peritectic Reactions
      4.3. Textures of More Complex Systems
      4.4. Textures of Systems Comprising Volatile Constituents
      4.5. Textures of Systems Precipitating Solid Phases of Different Densities
      4.6. 'Spinifex' Textures
5 / Orders of Crystallization in Metamorphic Rocks
      5.1. Reaction Microtextures
      5.2. Crystallization-Deformation Relations
      5.3. Pre-, Syn-, and Post-Kinematic Minerals
            5.3.1. Pre-Kinematic Minerals
            5.3.2. Post-Kinematic Minerals
            5.3.3. Syn-Kinematic Minerals
            5.3.4. Superposed Crystallization and Deformations

III: Examples of Microtextures
6 / Principal Textures of Igneous Rocks
      6.1. Classification of the Principal Igneous Rocks
      6.2. Thin Sections of Igneous Rocks
7 / Principal Textures of Metamorphic Rocks
      7.1. Classification of Tectonite Textures
      7.2. Petrochemical Classification of Metamorphic Rocks
      7.3. Thin Sections of Metamorphic Rocks

Notes
References

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