Continental reactivation and reworking

Contents......Page 6
Continental reactivation and reworking: an introduction......Page 10
Fig. 1. (a) Generalized map of central Australia showing the location of major .........Page 14
Fig. 2. Schematic diagram depicting the fault rocks/fabrics, strain distribution, tectonic style .........Page 17
Fig. 3. Shear wave-speed structure in the vicinity of the Proterozoic Broken .........Page 18
Mechanisms of lithospheric renewal associated with continental orogeny......Page 22
Fig. 1. Proposed mechanisms by which continental lithospheric mantle is renewed: (a) .........Page 24
Fig. 2. Variation of the functions C[sub(n)](kh) (equations 2 and 8) that describe .........Page 26
Fig. 3. Variation with time of maximum downward displacement (a) and maximum .........Page 28
Fig. 4. Perturbation Z[sub(0)] required for instability to occur, as a function .........Page 30
Fig. 5. Initial density and velocity fields for 2D numerical experiments shown .........Page 32
Fig. 6. Finite deformation and the growth of the gravitational instability for experiments .........Page 33
Fig. 7. Finite deformation and the growth of the gravitational instability for experiments .........Page 34
Fig. 8. P-wave speed variations in the lithosphere beneath a traverse perpendicular .........Page 36
Fig. 9. A distribution of relative P-wave speed anomaly (in km/s) beneath the .........Page 37
Fig. 10. Topography shown by this shaded relief image of the Betic .........Page 39
Fig. 11. Variations in S-wave speed beneath central Asia at depths of .........Page 41
The role of deep basement during continent–continent collision: a review......Page 48
Fig. 1. Outline geological maps of collisional orogens with coherent eclogite facies .........Page 49
Fig. 2. Plots showing the increase in lithospheric density for a lithosphere .........Page 51
Fig. 3. (a) Shows model geotherms for the Alps assuming continental subduction at .........Page 52
Fig. 4. Plots of pressure temperature estimates for eclogites in collisional orogens. .........Page 53
Fig. 5. (a) Finite element mesh for a vertical stretch orogen after 32 Ma .........Page 54
Fig. 6. Curves showing the thickness of crust (Cz) of a given .........Page 57
Fig. 7. Model curves showing the topography that would be developed by a crust .........Page 58
Fig. 8. (a) Transient 2-dimensional finite element thermal model 15 Ma after delamination .........Page 59
Table 1. Model and measured densities for eclogite facies rocks and their precursors......Page 50
Table 2. Assumptions made in the finite element models presented in Figures 5 and 8......Page 55
When the Wilson Cycle breaks down: How orogens can produce strong lithosphere and inhibit their future reworking......Page 66
Fig. 1. A portion of continental lithosphere is subdivided into three domains, .........Page 67
Fig. 2. Global distribution of orogens. Orogens that are positioned along present-day .........Page 68
Fig. 3. Rheological profiles and geothermal gradients of four lithospheric models. See .........Page 71
Fig. 4. P–T diagram with water content (wt.%) within stable mineral assemblages .........Page 74
Fig. 5. Rheological profiles and geothermal gradients of three lithospheric models with .........Page 75
Fig. 6. (a) Simplified map of the East Greenland and Scandinavian Caledonides, in a .........Page 78
Fig. 7. Tectonic map of the Urals (modified after Ivanov et al. 1975; .........Page 79
Fig. 8. Schematic cross-section through the Urals, based on surface geology, seismic .........Page 80
Fig. 9. (a) Rheological profile and geothermal gradient of the present-day Urals lithosphere .........Page 81
Table 2. Parameters and calculated results used for single layer models......Page 69
Table 3. Parameters and calculated results used for two-layer models......Page 70
From lithospheric thickening and convective thinning to active continental rifting......Page 86
Fig. 1. Thinning of the lithospheric mantle related to a thermal plume .........Page 87
Fig. 2. Four elementary processes may affect the vertical geometry of the lithosphere .........Page 88
Fig. 3. (a) Evolution of the geometry of the lithosphere assuming a homogeneous tectonic .........Page 92
Fig. 4. Evolution of the geometry of the lithosphere following homogeneous tectonic .........Page 93
Fig. 5. The contrast in gravitational potential energy between a deformed lithospheric column .........Page 94
Fig. 6. Back-arc extension as an example of post-convective thinning active continental .........Page 95
Table 1. List of parameter values......Page 90
Episodicity during orogenesis......Page 98
Fig. 1. The Alpine–Himalayan orogenic belt stretches from Spain to New Zealand. .........Page 99
Fig. 2. Part of the global eustatic record (modified from Haq et al. 1987). .........Page 103
Fig. 3. Switches in tectonic mode may be a natural consequence of .........Page 106
Fig. 5. Buoyancy-driven exhumation of the UHP rocks of the Tso Morari .........Page 107
Fig. 6. Schematic illustration of the geometry of an orogenic surge. (a) .........Page 108
Fig. 8. Formation and exhumation of UHP rocks of the Tso Morari dome. .........Page 109
Fig. 9. Orogenic surges after accretion events can lead to a distinctive pattern .........Page 111
The structure and rheological evolution of reactivated continental fault zones: a review and case study......Page 124
Fig. 1. Schematic strength v. depth profile for 'average' continental lithosphere showing .........Page 126
Fig. 2. Schematic diagram showing depth, fault rock distribution and deformation regimes .........Page 127
Fig. 3. Lithological (unshaded) and environmental (grey shading) factors controlling the fault-rock .........Page 129
Fig. 4. (a) Regional map of the UK and Irish Caledonides showing the .........Page 131
Fig. 5. Schematic regional NW–SE cross-sections through: (a) northwest Highland block; (b) .........Page 132
Fig. 6. (a) Plan of NE trending, mainly sinistral shears related to the .........Page 134
Fig. 7. Maps showing (a) protolith geology and (b) GGFZ-related deformation intensiy .........Page 135
Fig. 8. (a) Maps showing (i) protolith geology and (ii) GGFZ-related deformation .........Page 138
Fig. 9. Hydrated fault rocks from the core regions of the GGFZ. .........Page 139
Fig. 10. Schematic 3-D strength profiles through a vertical, crustal-scale fault zone .........Page 142
Geodynamics of Central Australia during the intraplate Alice Springs Orogeny: Thin viscous sheet models......Page 148
Fig. 1. Sketch of Australia showing the crustal mega-elements defined by Shaw .........Page 149
Fig. 2. (a) Central Australia, regional geology (ANC, Arltunga Nappe Complex). (b) .........Page 150
Fig. 3. (a) Regional geology of the Canning Basin. (b) Generalized cross-section of .........Page 151
Fig. 4. (a) Schematic representation of boundary conditions used in the thin viscous .........Page 154
Fig. 5. (a) Undeformed finite element mesh used to calculate deformation within the .........Page 157
Fig. 7. Time dependence of the three principal deformation indicators: (a) displacement .........Page 158
Fig. 8. Data for all n = 1 experiments showing the dependence of the .........Page 159
Table 1. T´[sub(x)] and T´[sub(y)] coefficients for n = l experiments......Page 161
Fig. 10. Data for all n = 3 experiments showing the power-law dependence of .........Page 162
Table 2. T´[sub(x)] and T´[sub(y)] coefficients for n = 3, H/D = 1.4 and W/H = 1.0......Page 163
Fig. 12. The dependence of ln[β[sub(max)]] on θ for all the experiments .........Page 166
Fig. 13. Schematic model (shown in vertical section) used to estimate the .........Page 167
Fig. 14. The dependence of plate boundary force per unit length F[sub(x)] .........Page 169
Fig. 16. Maximum crustal thickening factor (β[sub(max)]) v. Moho temperature in the .........Page 170
Table 4. Coefficients of T´[sub(x)] and T´[sub(y)] for n = 3, H/D = 1.4 and W/H = 0.5......Page 164
A thin-plate model of Palaeozoic deformation of the Australian lithosphere: Implications for understanding the processes of cratonization, orogenesis, reactivation and reworking......Page 174
Fig. 1. Schematic representation of the coupling between deformation and strength in .........Page 179
Fig. 2. Initial strength distribution assumed in the numerical model expressed as .........Page 180
Fig. 3. Distribution of seismic surface wave anomalies along a 100 km deep .........Page 181
Fig. 4. Summary of the velocity boundary conditions imposed along the margins .........Page 183
Fig. 5. Contour plots of the logarithm of the computed strain rate .........Page 185
Fig. 6. Contour plots of the computed accumulated strain rate at 12 .........Page 186
Fig. 7. Contour plots of the computed crustal thickness at 12 selected .........Page 187
Fig. 8. Contour plots of the computed Moho temperature at 12 selected .........Page 188
Fig. 9. Contour plots of the computed surface topography at 12 selected .........Page 189
Fig. 10. Contour plots of the computed cumulative denudation and sediment accumulation .........Page 190
Fig. 11. Plot of the computed instantaneous velocity vectors at 12 selected .........Page 191
Fig. 12. Contour plots of the logarithm of the computed strain rate .........Page 193
Fig. 13. Contour plots of the computed surface topography at 12 selected .........Page 194
Fig. 14. Contour plots of the logarithm of the computed strain rate .........Page 196
Fig. 15. Comparison between results of two model runs differing by the .........Page 197
Fig. 16. Outline of the regions which, according to the tectonic element .........Page 198
Table 1. Model parameter values......Page 178
Table 2. Correspondence between the velocity boundary conditions shown in Figure 4 and .........Page 184
Tectonic feedback, intraplate orogeny and the geochemical structure of the crust: a central Australian perspective......Page 204
Fig. 1. Geological map and crustal scale-cross section of the central Australian .........Page 205
Fig. 2. Isopach maps for the Centralian Superbasin constructed for time intervals .........Page 208
Fig. 3. (a) Image of heat production in the western Macdonnell Ranges (Hermannsburg .........Page 209
Fig. 4. Illustration of the thermal consequences of burial of an anomalous .........Page 212
Fig. 5. Illustration of the long-term thermal effects of (a) exhuming a .........Page 214
Fig. 6. Illustration of the effect of a heat source distribution (a) on .........Page 215
Fig. 7. Schematic illustration of the way in which crustal stretching and .........Page 216
Fig. 8. With a suitable chosen length scale (equation 3, Appendix 1), the long .........Page 217
Fig. 9. Illustration of the rheological effects of progressive denudation of a .........Page 218
Fig. 10. h–q[sub(c)] space contoured for vertically-integrated strength normalized against a lithosphere .........Page 219
Fig. 11. In order to illustrate the effect of the horizontal length .........Page 220
Fig. 12. Estimated values of mean displacement rates, v and appropriate length .........Page 221
Fig. 13. Kinematic model for intraplate deformation on the Redbank Shear Zone .........Page 222
Fig. 14. Thermal consequences of displacement rate for kinematic model as shown .........Page 223
Fig. 15. The principle of "tectonic feedback" is illustrated with reference to .........Page 224
Long term thermal consequences of tectonic activity at Mt Isa Australia: Implications for polyphase tectonism in the Proterozoic.......Page 228
Fig. 1. (a) Location of the Mount Isa Inlier (MII) in north-western Queensland, .........Page 229
Fig. 2. Tectono-stratigraphic history of the Mount Isa Inlier. Major magmatic, and .........Page 231
Fig. 3. Interpreted seismic section from the WFB, MII (compiled from Drummond .........Page 233
Fig. 4. Granites, and comagmatic volcanics, of the Mount Isa Inlier. (a) Granites .........Page 236
Fig. 5. Two alternative models for the distribution of heat sources in .........Page 237
Fig. 7. Effects of changing heat source distribution on lower crustal temperature. .........Page 239
Fig. 8. h–q[sub(c)] paths appropriate to the sequence of events associated with .........Page 241
Table 1. Global and Australian Proterozoic heat flow data......Page 232
Table 2. Geochemistry and heat production of selected granites of the Mount Isa Inlier......Page 234
Table 3. Geochemistry and heat production of major sedimentary units of the Mount Isa Inlier......Page 235
Table 4. Characteristics of main phases of magmatism in the Mount Isa Inlier......Page 240
Polymetamorphism and reworking of the Reynolds and Anmatjira Ranges, central Australia......Page 246
Fig. 1. Simplified map of the Arunta Inlier showing the location of .........Page 247
Fig. 2. Generalized geology of the Reynolds–Anmatjira region (modified after Stewart, 1981). .........Page 248
Fig. 3. Simplified geology of the Mt Stafford region in the northwestern Anmatjira .........Page 250
Fig. 4. Regional distribution of metamorphism inferred to be associated with the .........Page 251
Fig. 5. (a) Contact metamorphic cordierite in the Lander Rock Beds immediately adjacent .........Page 252
Fig. 6. Structural–metamorphic relationships in the southeastern Anmatjira Range. (a) Foliation defined .........Page 253
Fig. 7. Partially resorbed garnet surrounded by cordierite (X[sub(Fe)] = 0.41) and enclosed by .........Page 254
Fig. 8. (a) Simplified geological map of the Reynolds–Anmatjira Range region showing the .........Page 255
Fig. 9. Distribution of c. 1580 Ma U/Pb ages in the Reynolds–Anmatjira region from .........Page 256
Fig. 10. (a) Garnet-bearing leucosomes overprinting the regional foliation in peraluminous granitic gneiss .........Page 257
Fig. 11. Structural cross-sections through the southeastern Anmatjira Range (a), and the .........Page 258
Fig. 12. Distribution of large-scale kink-style folds that formed late in the .........Page 259
Fig. 13. Distribution of shear zones in the Reynolds–Anmatjira region that either .........Page 260
Fig. 14. Metamorphic zones defined by mid-Palaeozoic metapelitic shear zone assemblages in .........Page 261
Fig. 15. Heat production rates for the major outcropping granitic bodies in .........Page 265
Table 1. Emplacement ages (zircon U–Pb) of granitic units in the Reynolds–Anmatjira region......Page 249
High-grade reworking of Proterozoic granulites during Ordovician intraplate transpression, eastern Arunta Inlier, central Australia......Page 270
Fig. 1. Map of part of the Arunta Inlier showing major Palaeozoic .........Page 271
Fig. 2. Regional geological map of the Huckitta region of the eastern .........Page 273
Fig. 3. Map of the primary region of study, with Kanandra Granulite .........Page 275
Fig. 4. Photomicrographs from the Kanandra Granulite in the Huckitta region. (a) .........Page 277
Table 3. Summary of results for SHRIMP U–Th–Pb analyses, sample ISHU98.237......Page 286
Table 4. Summary of Sm–Nd analytical data for sample ISHU98.156......Page 287
Fig. 7. (a) Summary of P–T constraints for different stages of metamorphism in .........Page 288
Fig. 8. Schematic N–S cross-section across the eastern Arunta Inlier (adapted and .........Page 292
Table 1. Summary of conventional P–T estimates and Thermocalc results for selected .........Page 281
Table 2. Summary of SHRIMP U–Th–Pb monazite results for sample ISHU98.237......Page 285
Table 5. Summary of the evolution of Harts Range Group and Strangways .........Page 289
The response of U–Pb mineral chronometers to metamorphism and deformation in orogenic belts......Page 298
Table 1. Mineral isotopic closure temperatures......Page 300
Fig. 2. Photographs of Early Proterozoic structures re-worked by a Tertiary structural–metamorphic .........Page 302
Fig. 3. U–Pb concordia showing a summary of more than 50 analyses of .........Page 303
Fig. 4. Scanning electron micrographs of reaction textures involving accessory minerals. (a) .........Page 304
Fig. 5. Microscopic images of external and internal morphologies of zircon from .........Page 305
Fig. 6. U–Pb concordia diagram of zircon, allanite and titanite from granitic .........Page 307
Polyphase deformation and metamorphism at the Kalahari Craton – Mozambique Belt boundary......Page 312
Fig. 1. Locality map showing the study area astride the boundary between .........Page 313
Fig. 2. Geological map of the study area. The sample localities of .........Page 314
Fig. 3. (a, b) Two phases of migmatite development in the Vandusi Migmatite Gneiss .........Page 315
Fig. 4. Map showing the four structural domains recognized in the study .........Page 317
Table 2. Rb/Sr isotopic data for the Messica Granitic Gneiss......Page 320
Fig. 6. (a) Cathodoluminescence images of representative zircons from sample NHF. The elliptical .........Page 321
Fig. 7. (a) A Wetherill U–Pb concordia plot of the SHRIMP analyses for .........Page 323
Fig. 8. (a–f) [sup(40)]Ar/[sup(39)]Ar step heating profiles for six mica samples taken across .........Page 325
Table 1. Table correlating the sample localities shown in Figure 2 with .........Page 318
Table 3. Summary of SHRIMP U–Pb zircon results for sample NHF......Page 322
Table 4. Summary of SHRIMP U–Pb zircon results for sample CVGN......Page 324
Table 5. [sup(40)]Ar/[sup(39)]Ar data for six mica samples from the study area......Page 327
Polymetamorphism of mafic granulites in the North China Craton: textural and thermobarometric evidence and tectonic implications......Page 332
Fig. 1. Tectonic map of China showing the major Precambrian blocks and .........Page 333
Fig. 3. Spatial distribution of A- and B-type mafic granulites in the .........Page 334
Fig. 4. Schematic diagram showing the representative textures of A-, B- and .........Page 335
Fig. 5. Back-scattered electron images of textural features in the AB-type mafic .........Page 336
Fig. 6. Contrasting P–T paths inferred for the first (M[sub(1a)], M[sub(1b)], M[sub(1c)]) .........Page 347
Table 1. Metamorphic stage, mineral assemblages, reaction textures and possible reactions in .........Page 337
Table 2. Microprobe analyses of garnet......Page 339
Table 3. Microprobe analyses of plagioclase......Page 342
Table 4. Microprobe analyses of orthorpyroxene......Page 343
Table 5. Microprobe analyses of clinopyroxene......Page 344
Table 7. P–T estimates for M[sub(1a)]......Page 345
Table 9. P–T estimates for M[sub(1b)] and M[sub(2a–c)] by THERMOCALC......Page 346
Pervasive Pan-African reactivation of the Grenvillian crust and large igneous intrusions in central Dronning Maud Land, East Antarctica......Page 352
Fig. 2. Geological overview map of central Dronning Maud Land (cDML) (mostly .........Page 353
Fig. 3. Geochronological data on rocks from central Dronning Maud Land based .........Page 357
Fig. 4. Geological section along the Conradgebirge in the Orvinfjella (for location see Fig. 2).......Page 359
Table 1. Geological events in central Dronning Maud Land based on Soviet .........Page 355
Table 2. Geological succession in central Dronning Maud Land based on East .........Page 356
Fluid-rock interaction in the Reynolds Range, central Australia: superimposed, episodic, and channelled fluid flow systems......Page 366
Fig. 1. Geological map of the Reynolds and Anmatajira Ranges simplified from .........Page 368
Fig. 2. Plot of Lander Rock Beds δ[sup(18)]O values v. distance from .........Page 371
Fig. 4. Summary T-XCO[sub(2)] diagram in the K[sub(2)]O–CaO–MgO–Al[sub(2)]O[sub(3)]–SiO[sub(2)]–H[sub(2)]O–CO[sub(2)] system (KCMAS) at 450 MPa .........Page 373
Fig. 5. Summary of δ[sup(13)]C v. wt% carbonate (a) and the δ[sup(13)]C and .........Page 376
Fig. 6. Generalized map of part of the Woodford River locality summarizing .........Page 377
Fig. 8. Summary of δ[sup(18)]O values of the Lower Calcsilicate Unit calcpelites .........Page 378
Fig. 9. (a) Summary of geochemical changes in Alice Springs shear zones cutting .........Page 379
Fig. 10. δ[sup(18)]O values of granites, metapelites, and quartz veins from the .........Page 380
Fig. 11. δ[sup(18)]O values of granites, Lander Rock Bed pelites, and quartz .........Page 381
Fig. 13. Patterns of calcite δ[sup(18)]O values in a single retrogressed calcite .........Page 384
Table 1. Summary of fluid flow episodes in the Reynolds Range......Page 369
The effects of early Cambrian metamorphism in western Dronning Maud Land, East Antarctica: a carbon and oxygen isotope study of fluid–rock interaction in the Sverdrupfjella Group......Page 390
Fig. 1. Regional Geological Map of western Dronning Maud Land, East Antarctica. .........Page 391
Fig. 2. Calc-silicate rocks and vein types sampled in the central Kirwanveggen. .........Page 393
Fig. 3. Plot of δ[sup(13)]C and δ[sup(18)]O v. wt.% calcite (a, b) in .........Page 397
Fig. 4. Plot of quartz δ[sup(18)]O (vein) v. whole-rock δ[sup(18)]O (host) for .........Page 399
Fig. 5. Histogram showing the range of δ[sup(18)]O values of retrogressed gneiss .........Page 400
Table 1. Whole–rock oxygen isotope data for retrogressed rocks......Page 395
Table 2. Oxygen and carbon isotope data for carbonate rocks......Page 396
Table 3. Oxygen and carbon isotope data for quartz and quartz–calcite veins......Page 398
A......Page 404
C......Page 405
E......Page 407
G......Page 408
H......Page 409
L......Page 410
M......Page 411
N......Page 412
P......Page 413
S......Page 414
V......Page 416
Z......Page 417