Flow Processes in Faults And Shear Zones (Geological Society Special Publication No. 224)

Contents......Page 6
Fig. 1. Banded orthogneiss with darker amphibolite layers displaying dextral offset across .........Page 10
Fig. 2. Aeromagnetic map of part of the 180 km long Nordre .........Page 11
Fig. 3. General graphs (partly modified from Knipe 1989) and schematic sketches .........Page 12
Fig. 4. Schematic strength profile through the crust and upper mantle illustrating .........Page 13
Fig. 6. Diffuse zone of shearing between quartzofeldspathic orthogneiss (right-hand side of .........Page 14
Fig. 7. Outcrop-scale dextral shear zone developed in pelite at Cap de .........Page 15
Fig. 8. Minor aplite intrusion rotated and attenuated by sinistral shears formed .........Page 16
Shear zones in the upper mantle: evidence from alpine- and ophiolite-type peridotite massifs......Page 20
Fig. 1. Shear zone features in selected mantle massifs (see references in .........Page 21
Fig. 2. Photomicrographs of typical mantle deformation microstructures. Photo (e) in plane.........Page 24
Fig. 5. Scanning electron microscope (SEM) backscatter image of grain boundary alignments .........Page 26
Fig. 6. SEM Backscatter images showing evidence for production of fine-grained material .........Page 27
Fig. 7. Pressure–temperature grid with exhumation paths for Pyrenean ('Py'; e.g. Turon de .........Page 28
Fig. 8. Possible tectonite and mylonite shear zones in extensional and transcurrent .........Page 29
Table 1. Peridotite massifs with evidence for localized deformation......Page 22
Fig. 1. Location map of Clarke Head megabreccia containing mylonitized granulite blocks .........Page 34
Fig. 2. Field relationships of the granulites. (a) Megabreccia near Clarke Head, .........Page 35
Fig. 3. Mylonite microstructures. (a) Typical pyroxene grains in plagioclase matrix. Pyroxene .........Page 37
Fig. 4. Ultramylonite microstructures. (a) Contact between mylonite and ultramylonite bands separated .........Page 38
Fig. 5. Microstructures associated with the transition from Zone II to Zone .........Page 39
Fig. 6. Cherty ultramylonite (deformed pseudotachylyte). (a) Cherty mylonite – mylonite contact. Unlike .........Page 40
Fig. 7. Schematic chart of microstructure evolution during deformation. The diagram illustrates .........Page 42
Fig. 8. A plot of the width of localized deformation zones (black .........Page 43
Microstructural evolution in a mylonitic quartz simple shear zone: the significant roles of dauphine twinning and misorientation......Page 48
Fig. 1. SEM images of Torridon shear zone (XZ section plane), (a) .........Page 50
Fig. 2. Equal area, upper hemisphere quartz pole figures for different parts .........Page 51
Fig. 3. Quartz crystallography. (a) Principal directions in quartz (after Linker et .........Page 53
Table 2. Relationships between specific quartz crystal slip systems (SPN: slip plane .........Page 54
Fig. 5. SEM/EBSD analysis of localized dauphine twin microstructures (see Fig. 1a for .........Page 57
Fig. 6. Petrofabric and misorientation analysis of a linear traverse across the .........Page 60
Fig. 7. Summary of grain boundary misorientation analyses results. (a) Relationship between .........Page 62
Fig. 8. Dauphine twinning and twin boundaries in quartz. (a) Quartz single .........Page 63
Fig. 9. Schematic model for shear zone grain size reduction and mylonite .........Page 64
Table 1. Summary of Torridon shear zone auto-EBSD experiments (see Fig. la for .........Page 52
Table 3. Relationships between quartz crystal-slip systems (R: unique rotation axis; SD: .........Page 55
The application of GIS to unravel patterns of deformation in high grade terrains: a case study of indentor tectonics from west Greenland......Page 72
Fig. 1. Schematic map of the geology of the Nagssugtoqidian Orogen and .........Page 73
Fig. 3. Summary figures of structural dataset; (a) representation of foliation trend .........Page 75
Fig. 4. Selected geophysical data; (a) total magnetic field data with shading .........Page 78
Fig. 5. Combination of directional structural data and total magnetic signature; (a) .........Page 79
Fig. 7. The total magnetic intensity with overlay of the metamorphic grade, .........Page 82
Fig. 8. Proposed indentor model and the resulting structural features: increase in .........Page 83
Fig. 9. Schematic indentor model with expected fabric type patterns.......Page 84
Rheology of a two-phase material with applications to partially molten rocks, plastic deformation and saturated soils......Page 88
Fig. 1. Schematic map of plastic deformation. T[sub(m)] is the melting temperature, .........Page 90
Fig. 2. Stress (σ) versus strain rate (ε) on a log–log diagram for .........Page 91
Fig. 3. Three-dimensional diagram (ε–η–Φ) showing the cusp shape of viscosity for low strain rate values.......Page 92
Fig. 4. Three-dimensional diagram (ε–η–Φ) showing the cusp shape of viscosity for .........Page 93
Fig. 5. Deformation at high strain rates, or high stress, as it .........Page 94
Fig. 7. Deformation under common stress at low strain rates, as it .........Page 95
Fig. 8. Deformation under common low strain rates. Overlapping of the two .........Page 96
Fig. 9. Differences between melting and crystallization for the rheology of PMR. .........Page 97
Fig. 10. Hysteresis during cyclic loading and unloading of a PMR. Repeated loading .........Page 99
A comparison of structural data and seismic images for low-angle normal faults in the Northern Apennines (Central Italy): constraints on activity......Page 104
Fig. 1. Crustal-scale cross-section from Elba to the Adriatic coast. The profile .........Page 105
Fig. 2. Schematic structural map of the Umbria region. The map is .........Page 107
Fig. 3. Geological cross-section through the Perugia Mountains (see location in Fig. 2.) .........Page 109
Fig. 4. Line drawing of a commercial seismic reflection profile through the .........Page 110
Fig. 5. (a) Earthquake locations for the study area recorded by a detailed .........Page 111
Fig. 6. (a) Schematic stratigraphy of the five complexes exposed in the .........Page 113
Fig. 7. Outcrop photo of the Zuccale fault. The fault separates Upper .........Page 114
Fig. 8. Cartoon showing the architecture of the ZF and the minor.........Page 115
Fig. 9. (a) Outcrop photo of the C-type shear bands within the fault .........Page 116
Fig. 10. (a) Outcrop photo of the younger system (V[sub(2)] of the .........Page 117
Shear deformation of pelitic rocks in a large-scale natural fault......Page 122
Fig. 1. Geological map of the eastern foothills of the Southern Apennines .........Page 123
Fig. 3. Simplified geological map showing the distribution of the Pliocene–Pleistocene smectite-bearing .........Page 124
Fig. 5. The Scorciabuoi shear zone is recognized by the markedly darker .........Page 125
Fig. 7. Schematic representation of smectite and its hydration state in relation to the imposed effective stress.......Page 126
Fig. 8. Grain size profiles of undeformed wall rock mudstones (empty circles) .........Page 127
Fig. 9. Evolution of shear fabric with increasing strain, as reported from .........Page 128
Fig. 11. Schematic cross-sections through the SBF shear zone illustrating the inhomogeneous .........Page 129
Fig. 12. Equal angle stereographic projections showing the orientation of meso-scale shears .........Page 130
Fig. 14. Scanning electron micrographs obtained from the peels shown in Fig. 13. .........Page 132
Insights from the Ocean Drilling Program on shear and fluid-flow at the mega-faults between actively converging plates......Page 136
Fig. 1. Schematic maps and cross-sections to show the location and general .........Page 137
Fig. 2. Annotated schematic log based on cores from the Barbados décollement .........Page 138
Fig. 3. Annotated schematic logs based on cores from the Costa Rica .........Page 139
Fig. 4. Annotated schematic log based on cores from the Nankai décollement .........Page 140
Fig. 5. Depth profiles of selected chemical species in pore-fluids across the .........Page 141
Fig. 6. Lateral fluid content variations at the Barbados plate-boundary fault inferred .........Page 142
Fig. 7. Variations with depth of sediment density across décollement and proto-décollement .........Page 143
Fig. 8. Depth profiles of porosity, chloride and propane (C[sub(3)]) in pore-fluids .........Page 144
Fig. 9. Depth profiles of porosity and chloride concentration across the Nankai .........Page 145
Fig. 10. Summary diagram of features at the three mega-shear zones described in this paper.......Page 147
Contrasting styles of fluid–rock interaction within the West Fissure Zone in northern Chile......Page 150
Fig. 1. Overview sketch of Northern Chile showing morphological units and the .........Page 151
Fig. 2. Landsat TM scene showing the WFZ with the position of .........Page 152
Fig. 3. Geological maps of the areas of detailed investigations. (a) Quebrada .........Page 153
Fig. 4. Photographs of fault-related deformation structures from the Guatacondo region (a–b) .........Page 156
Fig. 5. Histograms showing (a) ice melting temperature (profiles A and C). .........Page 157
Fig. 6. Diagrams of stable isotope data. (a) Crossplot of the δ[sup(18)O and .........Page 159
Fig. 7. Diagrams of trace element distribution. (a) Shale-normalized rare-earths and ytrium .........Page 161
Fig. 8. Whole-rock analyses of selected oxides (%) and trace elements (ppm) .........Page 163
Fig. 10. Isotopic composition of host rock (monzodiorite), fault-related rocks (monzodiorite) from .........Page 164
Table 5. Whole-rock analysis of fault rocks from Profile C (oxides and trace elements)......Page 165
Table 1. Sampling profiles......Page 155
Table 2. Isotope data......Page 158
Table 3. Concentration of selected trace elements in calcite veins (V) and their limstone host (profile A)......Page 160
Table 4. Whole rock analysis of fault rocks from Profile B (oxides and trace elements)......Page 162
Ductile shearing, hydrous fluid channelling and high-pressure metamorphism along the basement–cover contact on Sikinos, Cyclades, Greece......Page 170
Fig. 1. Geological map of the Attic-Cycladic massif, modified after Van der Maar and Jansen (1983).......Page 171
Fig. 2. Geological map of Sikinos (after Van der Maar et al. 1981 and Franz et al. 1993).......Page 172
Fig. 3. Geological map of the eastern basement outcrop on Sikinos. Note .........Page 173
Fig. 4. Field relations in basement rocks. (a) F[sub(H2)] isoclinal folding of .........Page 174
Fig. 5. Equal area foliation pole and lineation plots for the basement .........Page 175
Fig. 6. Schematic representation of basement–cover relations on Sikinos. Metapelitic gneisses and .........Page 176
Fig. 7. Photomicrographs (a) to (d) depict the transformation from granodiorite in the .........Page 177
Fig. 8. Transformation sequence from metapelitic gneiss in the basement 'core' to .........Page 179
Fig. 9. Pressure–temperature estimates for high-pressure metamorphism in basement rocks calculated from .........Page 180
Shear zone folds: records of flow perturbation or structural inheritance?......Page 186
Fig. 1. Summary schematic diagrams illustrating increasing deformation and evolution of fold .........Page 187
Fig. 2. Simplified geological map of the Moine and Naver Nappes in .........Page 189
Fig. 3. (a) Simplified structural map of the study area highlighting the .........Page 190
Fig. 4. (a) Asymmetric F[sub(3)] folds showing a reversal in fold vergence .........Page 192
Fig. 5. Detailed structural analysis of folding within the study area illustrating .........Page 193
Fig. 6. Frequency distribution histograms of fold hinges and axial planes from .........Page 194
Fig. 7. Frequency distribution histograms of transecting fold hinge angles from the .........Page 195
Fig. 8. Schematic sketches illustrating the geometric consequences of fold and fabric .........Page 197
Figure 9. Fabric topology plots of sheath fold and flow fold data .........Page 198
Fig. 10. Summary fabric topology plots showing the mean orientation (n = 750) of Z .........Page 200
Fig. 11. Summary fabric topology plots showing the mean orientation (n = 670) of Z .........Page 202
Fig. 12. Schematic stereographic plot illustrating how layering developed oblique to the .........Page 204
Fig. 13. Schematic 3D cartoon illustrating the geometry and orientation of synshearing .........Page 205
Table 1. Summary transection grid associated with a dome (antiform on culmination) .........Page 196
Table 2. Summary table of angular obliquities associated with a–g structural parameters in the study area.......Page 203
Geometric and kinematic analysis of a transpression terrane boundary: Minas fault system, Nova Scotia, Canada......Page 210
Fig. 1. Location map of the study area; (a) Northern shore Minas .........Page 211
Fig. 2. Contrasting styles of deformation in the Minas fault; (a) Contractional .........Page 213
Fig. 3. Fault rock units in the internal zone of the Minas .........Page 215
Fig. 4. Equal area lower hemisphere stereographic projections; (a) Marginal domain, internal .........Page 216
Fig. 5. Equal area lower hemisphere stereographic projections of foliations from the .........Page 217
Fig. 7. Scale independent schematic representation of the major structural features from .........Page 218
Fig. 8. Shear band domain, internal zone; (a) Dextral displacement by shear .........Page 219
Development of local orthorhombic fabrics within a simple-shear dominated sinistral transpression zone: the Arronches sheared gneisses (Iberian Massif, Portugal)......Page 224
Fig. 1. (A) Location of the study area of Arronches (Portugal) as part .........Page 226
Fig. 2. (A) Generalized cross-section through the CCSZ and adjacent margins (see Fig. 1 .........Page 227
Fig. 3. (A) Detailed structural map of the outcrops where the Arronches .........Page 228
Fig. 4. Meso- and microscopic structures observed in peralkaline gneisses from the .........Page 229
Fig. 5. Detailed structural map illustrating the intermediate sinistral domain (ISD) observed .........Page 231
Fig. 6. Meso- and microscopic structures from ultramylonites and peralkaline gneisses in .........Page 232
Fig. 7. Schematic representation of texture development for the Arronches peralkaline, with .........Page 233
Fig. 8. Diagram depicting the effect of progressive deformation on the development .........Page 234
Fig. 9. Schematic diagram illustrating a case of progressive deformation with development.........Page 235
Deformation in a complex crustal-scale shear zone: Errabiddy Shear Zone, Western Australia......Page 238
Fig. 1. Simplified geological map (modified after Occhipinti et al. 2004) of the .........Page 240
Fig. 2. Schematic diagram modified after Occhipinti et al. (2004) illustrating the possible .........Page 241
Fig. 3. Geological map of Archaean basement granitic gneiss. Coordinates are specified .........Page 242
Fig. 4. Equal area stereonets of early structural fabrics (Regional D[sub(1)] observed in each of the mapped areas.......Page 243
Fig. 5. Equal area stereonets of main structures (Regional D[sub(2)] observed in each of the mapped areas.......Page 244
Fig. 6. Equal area stereonets of brittle and brittle–ductile structures and F[sub(3) folds .........Page 245
Fig. 7. (a) A strong quartz aggregate mineral lineation on the S[sub(1/2n)] foliation .........Page 247
Fig. 8. Geological map of the Felsic gneiss–Bertibubba Supersuite in the Erong .........Page 248
Fig. 9. Geological map of Psammitic Gneiss (Quartpot Pelite). Coordinates are specified .........Page 249
Fig. 10. Field photographs of Palaeoproterozoic metasedimentary rocks of the Camel Hills .........Page 250
Fig. 11. Geological map of migmatized pelitic schist and gneiss-Quartpot Pelite. Coordinates .........Page 251
Fig. 12. Summary deformation networks from the four areas showing the general .........Page 253
Fig. 13. Model summarizing the evolution of the Errabiddy Shear Zone. (a) .........Page 254
Fig. 1. Kinematic models for deformation in highstrain zones: (a) simple shear; .........Page 258
Fig. 2. Geological overview map of the Virginia Piedmont. BHSZ: Brookneal high-strain .........Page 259
Fig. 3. (a) General shear with constrictional, plane and flattening strains. (b) .........Page 260
Fig. 4. (a) Steady state general shear deformation and non-steady state deformation .........Page 261
Table 1. Deformation parameters for plane strain and flattening strain deformations (Fig. 5)......Page 262
Fig. 6. Geological map of the Brookneal high-strain zone from the southwestern .........Page 263
Fig. 8. Photomicrographs of (a) undeformed Melrose granite. f: feldspar; q: quartz; .........Page 264
Fig. 9. Geological map of the Spotsylvania highstrain zone in the central .........Page 265
Fig. 11. (a) Dextral asymmetry in pegmatitic mylonite, outcrop surface approximately parallel to .........Page 266
Fig. 12. Idealized block diagram illustrating fabrics in the Spotsylvania high-strain zone. .........Page 267
Fig. 14. Schematic cross sections illustrating dextral transpressive deformation and development of .........Page 268
Fig. 15. Kinematic models for the SHSZ. All models are monoclinic, isovolumetric, .........Page 269
Fig. 16. Present day map with the 'palaeogeographic'position of Goochland Courthouse prior .........Page 270
Constraints on kinematics and strain from feldspar porphyroclast populations......Page 274
Fig. 1. (a) Block diagram of transpressional deformation modified from Sanderson & Marchini (1984). .........Page 276
Fig. 2. Construction of the fabric ellipsoid. (a) After each increment of .........Page 278
Fig. 3. Lower hemisphere projection stereonet plots of the rotational paths of .........Page 280
Fig. 4. (a) Stereonet plot of the initial orientation of an isotropic population .........Page 282
Fig. 5. The effect of aspect ratio on the progressive evolution of .........Page 283
Fig. 6. The effect of flow geometry (vorticity) on the progressive development .........Page 284
Fig. 7. (a) Schematic diagram of a population of ellipses orientated synthetic to .........Page 286
Fig. 9. Location of the western Idaho shear zone in the North .........Page 287
Fig. 10. (a) Geological map of the study area. The 4 km width .........Page 288
Fig. 11. (a) An outcrop photo showing the K-feldspar megacrysts of the .........Page 289
Fig. 12. Plot of anisotropies measured from field data against modelled anisotropies .........Page 292
Table 1. Summary of feldspar shape preferred orentation data......Page 290
Fig. 1. Major structural-metamorphic domains of the Armorican Massif, resulting from contrasted .........Page 296
Fig. 2. Simplified geology of Central Brittany (cross-section from Le Corre 1977).......Page 297
Fig. 3. Set of cleavage directional data used for geostatistical analysis and .........Page 299
Fig. 5. Strain restoration of the area shown in Fig. 3 (finite element .........Page 300
Fig. 6. (a) Omni-directional variogram calculated for cleavage directions in Central Brittany. The .........Page 301
Fig. 7. (a) Cleavage orientation contours computed from kriging interpolation. A NW–SE-striking band. .........Page 302
Fig. 8. Domainal distribution of interpolated cleavage directions outlined by a correlation .........Page 303
Fig. 9. Inversion of the deformation in eastern Central Brittany by N123° .........Page 305
Fig. 11. Restoration of some outlines of syntectonic plutons located along the .........Page 306
Fig. 12. Implications of the restoration of simple shear in eastern Central .........Page 307
Fig. A1. Example of a data set used for variogram computation, here .........Page 310
Fig. A3. Principle of data selection to compute an orientated variogram.......Page 311
Strain and deformation history in a syntectonic pluton. The case of the Roses granodiorite (Cap de Creus, Eastern Pyrenees)......Page 316
Fig. 1. Sketch of the main lithological units and structures in the .........Page 317
Fig. 2. Geological setting of the Roses granodiorite and the studied area. .........Page 318
Fig. 3. Schematic qualitative model of the structural history of Roses granodiorite. .........Page 319
Fig. 4. Mesoscopic scale structures in the Roses granodiorite. (a) Preferred orientation .........Page 320
Fig. 5. Pre-dyke finite strains obtained from two-dimensional analysis of enclave shapes .........Page 321
Fig. 6. Part of an extremely elongated enclave of quartz diorite with .........Page 322
Fig. 7. Structural map and strain analysis of pre-dyke structures and post-dyke .........Page 325
Fig. 8. Shear strain analysis across three sections in areas affected by .........Page 326
Fig. 9. Diagram of displacement against width measured in different sized shear .........Page 327
Shear zones and metamorphic signature of subducted continental crust as tracers of the evolution of the Corsica/Northern Apennine orogenic system......Page 330
Fig. 2. (a) Tectonic setting of Corsica within the western Mediterranean. (b) .........Page 331
Fig. 3. (a) Tectonic map of northern Corsica showing the main tectonic .........Page 332
Fig. 4. Geological map of the Tenda massif with the location of .........Page 333
Fig. 5. (a) Casta granodiorite, with synmagmatic deformed mafic xenolite. (b) Mylonitic .........Page 334
Fig. 6. (a) Examples of the GS2 high strain zone with shear .........Page 335
Fig. 7. Equal area projection (lower hemisphere) of foliation planes (open circles) .........Page 336
Fig. 8. Inferred pressure–temperature–time path of the Tenda massif. Gln-out taken .........Page 338
Fig. 9. Tectonic evolution of Alpine Corsica within the framework of the .........Page 340
Table 1. Significant HP/LT mineral assemblages in different rock types in the .........Page 337
Crenulation-slip development in a Caledonian shear zone in NW Ireland: evidence for a multi-stage movement history......Page 346
Fig. 1. (a) Regional geology of NW Ireland displaying localities referred to .........Page 347
Fig. 2. (a) Regional geology of Co. Mayo displaying localities referred to .........Page 348
Fig. 3. Geological map of South Achill and Achill Beg.......Page 349
Fig. 4. Angular relationships predicted between the shear zone wall and the .........Page 350
Fig. 5. (a) Asymmetrical buckle folds (F[sub(3)], interpreted as reverse slip crenulations (RSC). .........Page 351
Fig. 6. (a) Stereographic plot of the orientation of RSC-related structures in .........Page 352
Fig. 7. Geological map of the Callow Loughs area in the Central Ox Mountains.......Page 354
Table 1. [sup(40)]Ar–[sup(39)]Ar spot fusion data......Page 356
Table 3. Rb–Sr geochronology of Ox Mountains pegmatites from Flowerdew et al. (2000)......Page 358
Brittle–ductile shear zone evolution and fault initiation in limestones, Monte Cugnone (Lucania), southern Apennines, Italy......Page 362
Fig. 1. Location (a), geological setting (b), and (c) cross-section (no vertical .........Page 363
Fig. 2. Examples of different types of analysed structures. (a) Conjugate sets .........Page 366
Fig. 3. Orientation data (lower hemisphere, equal area projection). (a) Poles to .........Page 368
Table 1. Structural data (displacement data for 54 features are from Mazzoli & Di Bucci 2003)......Page 369
Fig. 5. En echelon vein arrays from Monte Cugnone plotted on the .........Page 371
Fig. 6. Sample line along the eastern quarry wall, showing spacing of .........Page 372
Fig. 7. Examples of microstructures from vein calcite. (a) Two sets of .........Page 373
Fig. 8. Fluid inclusion data. (a) Cumulative T[sub(m)] data (P: primary inclusions; S: .........Page 375
Fig. 9. Diagrams of displacement and shear strain for the 54 structures .........Page 376
Fig. 10. Graph of vein angle (α) vs. zone boundary angle (β). .........Page 377
Fig. 11. Schematic model for the rotation of tension gashes maintaining a .........Page 379
F......Page 384
L......Page 385
P......Page 386
T......Page 387
V......Page 388