Principles Of Metamorphic Petrology

by R. H. Vernon, G. L. Clarke

• ISBN13: 9780521871785
• ISBN10: 0521871786
• Format: Hardcover
• Copyright: 2008-04-07
• Publisher: Cambridge University Press

Summary

Principles of Metamorphic Petrology provides a modern introduction to the latest ideas, techniques and approaches in the study of metamorphic rocks. The book begins with basic concepts, but advances further than most other metamorphic petrology texts. Examples of this include the latest chemographic approaches, the correct use of pseudosections and the application of x-ray compositional mapping to metamorphic problems. It also covers recent advances in thermobarometry and the application of modern geochronological techniques to the absolute timing of tectonometamorphic events. Determination of parent rocks is covered in detail and there is a modern exposition of partial melting reactions, melt extraction and deformation of migmatites. The book includes a large number of references to lead students into independent investigation. A valuable text for advanced undergraduate and graduate courses in metamorphic petrology, that serves as the most current reference for researchers and exploration geologists.

Table of Contents

Preface	p. xi
Metamorphic Processes	p. 1
Introduction	p. 1
Effect of rock composition: The ACF diagram	p. 5
Metamorphic phase diagrams	p. 9
Metapelitic rocks and the AFM diagram	p. 11
Grade variations in contact metamorphism	p. 14
Illustrating regional metamorphic grade variations using the AFM diagram	p. 21
Extent of equilibrium	p. 26
Genetic classification of metamorphism	p. 32
Metamorphic facies	p. 32
Facies series	p. 38
Determining whole-rock composition and a volume of equilibration	p. 40
Open- versus closed-system behaviour during metamorphism	p. 41
Metamorphic Conditions: Chemography and Thermobarometry	p. 43
Introduction: Intensive factors, extensive factors and rock chemical composition	p. 43
Chemically zoned porphyroblasts and equilibration	p. 44
Equilibration during prograde metamorphism: Garnet growth in New Caledonian eclogites	p. 47
Corona reaction microstructures: Cohn Hill, Musgrave Block, central Australia and Rauer Group, Antarctica	p. 48
UHT microstructures and closure temperatures	p. 50
Recognition of metamorphic parageneses	p. 51
Equilibrium thermodynamics in petrology	p. 53
Chemical systems, components and end-members	p. 53
Thermodynamic variables and calculations	p. 55
Activity-composition relations and non-ideal mixing	p. 57
Thermobarometry	p. 58
Thermodynamic calculations for phase diagrams	p. 64
Tectonothermal History of Metamorphic Terranes	p. 71
Introduction and precautions	p. 71
Metamorphic grain shapes	p. 71
Low-energy grain shapes	p. 71
Low-energy shapes of inclusions	p. 74
Porphyroblasts	p. 74
Nucleation and growth of porphyroblasts	p. 74
Inclusions in porphyroblasts	p. 76
Inferring sequences of mineral assemblages ('metamorphic events')	p. 77
Concept of 'events'	p. 77
Criteria for inferring metamorphic reactions	p. 77
Using inclusions and folia wrapping porphyroblasts to infer metamorphic 'non-events'	p. 90
P-T-t paths	p. 91
Inferring time of growth of metamorphic mineral assemblages relative to time of formation of specific structures	p. 95
Introduction	p. 95
Inclusion trails in porphyroblasts	p. 95
Using porphyroblasts to determine the relative timing of metamorphic reactions and foliations (P-T-D-t paths)	p. 97
Criteria	p. 101
Examples of the approach	p. 117
Using inclusion trails in porphyroblasts to infer tectonometamorphic events	p. 120
Use of orthogonal inclusion trails in porphyroblasts	p. 120
Foliation inflection/intersection axes (FIAs)	p. 121
Absolute dating (geochronology) of mineral growth and foliation-forming events	p. 123
Introduction	p. 123
Radioactive decay principles	p. 123
Isochron calculations	p. 125
U-Pb dating of zircon in metamorphic rocks	p. 129
Dating of monazite in metamorphic rocks	p. 134
K-Ar and Ar-Ar dating	p. 137
Partial Melting during High-Grade Metamorphism	p. 140
Introduction	p. 140
Melting reactions	p. 140
Water-saturated melting reactions	p. 142
Water-undersaturated melting reactions	p. 145
Volumes of melt produced	p. 149
Compositions of partial melts	p. 149
Distinguishing between water-saturated and water-undersaturated melting	p. 150
Terminology of anatectic migmatites	p. 151
Non-anatectic migmatites	p. 154
Distinguishing anatectic from non-anatectic migmatites	p. 155
Stages of melting and melt migration	p. 157
Melting (anatectic) stage: Accumulation and movement of melt in source migmatites	p. 158
Melt retained in weakly deformed source rocks: Formation of patch and bedded migmatites	p. 158
Melt retained in more strongly deformed source rocks: Formation of stromatic migmatites	p. 164
Axial-surface leucosomes	p. 170
Multiple leucosomes	p. 173
Transport and local accumulation stage	p. 176
Melt segregation	p. 176
Melt segregation pathways in migmatites	p. 177
Effects of deformation on melt segregation	p. 178
Experimental melt segregation	p. 180
Diatexites	p. 180
Primary diatexites	p. 181
Secondary diatexites	p. 182
Segregation of solids from flowing melt in diatexites	p. 182
Near-source reaction processes in migmatites	p. 184
Migmatites and granite plutons	p. 185
Migmatite complexes as sources for high-level leucogranites	p. 186
Migmatite complexes as sources for typical S-type granites	p. 187
Sources of mafic components	p. 187
Are diatexites suitable sources of high-level S-type granites?	p. 188
Deeper source?	p. 188
Magma transport and formation of large granite bodies	p. 190
Heat source for crustal melting	p. 191
Retrograde reactions in cooling migmatites	p. 192
Deformation of migmatites	p. 193
Friction and impact melting	p. 198
Friction melting	p. 200
Impact melting	p. 200
Melting of sulphide-rich rocks	p. 205
Fluids and Metasomatism	p. 206
Fluids in Earth's crust	p. 206
Evidence of fluid flow in rocks undergoing metamorphism	p. 209
Sources of fluids in metamorphic rocks	p. 213
General comments	p. 213
Meteoric fluid	p. 215
Interaction with seawater	p. 216
Effect of fluid pressure on reaction curves	p. 216
Effect of fluid composition on mixed volatile reactions	p. 217
Effect of fluid composition on 'ionic' reactions	p. 221
Infiltration of fluid or not?	p. 223
General comments	p. 223
Fluids in regional metamorphism	p. 225
Fluids in contact metamorphism	p. 226
Fluids as heat transporting agents in regional metamorphism	p. 228
Metasomatism	p. 228
Local equilibrium in metasomatic processes	p. 229
Nature of metasomatic replacement reactions	p. 233
Types of metasomatism	p. 234
Introduction	p. 234
Mg metasomatism	p. 235
Na metasomatism and Na-Ca metasomatism	p. 235
Ca metasomatism	p. 235
K metasomatism	p. 235
Hydrolysis reactions (hydrogen-ion metasomatism; 'hydrolytic' alteration)	p. 237
Hydration-dominant reactions	p. 239
Skarns	p. 240
Fenitization	p. 242
'Blackwall' alteration	p. 243
How isochemical is prograde metamorphism?	p. 243
Metamorphic differentiation	p. 244
Extent of mass transfer and volume loss in deforming rocks	p. 244
Regional metasomatism	p. 245
Metasomatism in shear zones	p. 245
Regional Na metasomatism	p. 246
Regional Fe metasomatism	p. 249
Regional skarns	p. 250
Regional Si metasomatism	p. 250
Carbonic metasomatism?	p. 250
Metasomatism and ore deposits in metamorphic terranes	p. 251
Metamorphism superimposed on regional metasomatism	p. 251
Metasomatism accompanying regional metamorphism	p. 252
Deformation of Metamorphic Rocks	p. 257
Introduction	p. 257
Outline of deformation processes	p. 258
Brittle deformation	p. 258
Ductile deformation	p. 260
Crystal plasticity (dislocation creep)	p. 260
Diffusion creep	p. 266
Ductile grain-boundary sliding	p. 268
Conditions favouring various deformation mechanisms	p. 268
Recovery and recrystallization	p. 269
Recovery	p. 269
Recrystallization	p. 269
Deformation contrasts between minerals in rocks	p. 273
Chemical changes during deformation	p. 274
General effects of water	p. 274
Reaction strengthening	p. 275
Reaction weakening	p. 276
Deformation during prograde metamorphic reactions	p. 276
Deformation during retrograde metamorphic reactions	p. 277
Foliations and lineations	p. 277
Bedding-plane foliation	p. 279
Slaty cleavage	p. 280
Crenulation cleavage	p. 284
Gneissic foliation (gneissic layering)	p. 287
Composite (transposed) foliations in mylonitic rocks	p. 289
Layering in migmatites	p. 290
Interpretation of the origin of compositional layering (original or metamorphic?)	p. 292
Non-tectonic deformation of sedimentary structures: Structures produced by soft-sediment deformation	p. 302
Heterogeneous deformation ('deformation partitioning')	p. 303
Parent Rocks	p. 306
The general problem	p. 306
Metasedimentary rocks	p. 307
Broad chemical characteristics of metasedimentary rocks	p. 307
Residual structures of metapelitic and metapsammitic rocks	p. 310
Residual structures of calcareous metasediments	p. 320
Chemical metasediments	p. 324
Meta-igneous rocks	p. 326
Broad chemical characteristics of metamorphosed igneous rocks	p. 326
Residual structures in metamorphosed ignoeous rocks	p. 327
Residual structures in metamorphosed mafic igneous rocks	p. 334
Residual structures in metamorphosed felsic igneous rocks	p. 336
Sulphide-rich rocks	p. 348
Metasomatized parent rocks	p. 348
Appendix	p. 351
Glossary	p. 353
References	p. 363
Index	p. 435
Table of Contents provided by Ingram. All Rights Reserved.