Mineral Deposits & Earth Evolution

Contents......Page 6
Preface......Page 8
Acknowledgements......Page 11
Economic natural resource deposits at terrestrial impact structures......Page 12
Fig. 1. (A) Schematic cross-section of a terrestrial simple impact structure. No vertical .........Page 13
Fig. 3. Logarithmic plot of shock pressure (GPa) against post-shock temperature (°C) range .........Page 14
Fig. 4. Approximately 150 m high cliffs of impact melt rock at the edge .........Page 15
Fig. 5. Some shock metamorphic effects. (A) Shatter cones at Gosses Bluff impact structure. .........Page 16
Fig. 6. Shuttle topographic radar image of digital topography over the Carswell .........Page 19
Fig. 7. Geological map of the Carswell impact structure, indicating uplifted crystalline .........Page 20
Fig. 8. Photomicrographs of lithologies at Carswell. (A) Planar deformation features in quartz .........Page 21
Fig. 9. Geological map of the Witwatersrand Basin, with partially obscuring Karoo .........Page 22
Fig. 10. Distribution of large concentric structures and gold fields, with respect to .........Page 23
Fig. 11. Geological map of the Popigai impact structure (Table 2) indicating the distribution .........Page 24
Fig. 12. Field photograph of outcrop of the sheet of diamond-bearing impact melt .........Page 25
Fig. 15. Shatter cones in Huronian quartzite at the Sudbury impact structure.......Page 26
Fig. 16. Schematic stratigraphic section (not to scale) of lithologies at the Sudbury impact structure, .........Page 28
Fig. 18. Plot of (a) osmium and (b) neodymium isotopic data of ores and .........Page 29
Fig. 19. Three-dimensional mesh diagram of residual structure on the post-impact upper .........Page 31
Fig. 20. Thickness of rim facies at Viewfield impact structure (Table 2). Black dots .........Page 33
Table 1. Genetic groups of natural resource deposits at terrestrial impact structures......Page 17
Table 2. Deposits and/or indications of natural resources in terrestrial impact structures......Page 18
Gold mineralization within the Witwatersrand Basin, South Africa: evidence for a modified placer origin, and the role of the Vredefort impact event......Page 42
Fig. 1. Simplified geological map showing the subcrop of the Central Rand .........Page 43
Fig. 2. Summary of the main features of the stratigraphy of the .........Page 45
Fig. 3. Examples of mineralogical and textural associations of gold in the .........Page 48
Fig. 5. Silver and mercury contents of gold analysed in the present .........Page 51
Fig. 6. (a) Variation in Ag and Hg contents of all analysed gold .........Page 52
Fig. 7. Locations of gold occurrences in thin sections and the Ag .........Page 56
Fig. 8. Silver and mercury contents of Samples 4,5 and 7 from the .........Page 57
Table 2. Temperatures (in degrees Celsius) of chlorite formation derived from EPMA .........Page 58
Fig. 11. Examples of brittle deformation of minerals from the different reefs .........Page 60
Fig. 12. Location of the goldfields with respect to the known distribution .........Page 64
Table 1. Mineralogical associations of gold occurrences, analyses of which are presented .........Page 49
Metallogenic fingerprints of Archaean cratons......Page 70
Table 1a. Number of mineral deposits of selected element groups across Gondwana .........Page 72
Fig. 2. Mineral diversity of selected elements of Archaean cratons, as shown .........Page 76
Table 2c. Natural log of the spatial coefficient (ρ[Sub(ij)]) with standard errors .........Page 77
Table 3c. Natural log of the spatial coefficient (ρ[sub(ij)]) with standard error .........Page 79
Table 1c. Natural log of the spatial coefficient (ρ[sub(ij)]) with the approximate standard .........Page 73
Controls on the heterogeneous distribution of mineral deposits through time......Page 82
Fig. 1. Historical figure showing distribution through time of selected mineral deposits, .........Page 83
Fig. 2. (a) Frequency distribution of juvenile continental crust based on a total .........Page 87
Fig. 3. Depth and depth variation in composition of selected Archaean, Proterozoic .........Page 88
Fig. 4. Distribution of major nickel–copper sulphide deposits with time. Major sources .........Page 89
Fig. 5. Temporal distribution of epigenetic gold ± copper ± silver deposits compared with .........Page 90
Fig. 6. Temporal distribution of VHMS deposits compared with that of orogenic .........Page 92
Fig. 7. Temporal distribution of palaeoplacer and placer gold deposits, iron oxide .........Page 93
Fig. 8. Contrasting models for the evolution of the atmosphere, adapted from .........Page 96
Fig. 9. Temporal distribution of sediment-hosted deposits of redox-sensitive metals. (a) uranium .........Page 97
Fig. 10. Temporal distribution of sediment-hosted base-metal deposits. (a) Mississippi Valley type .........Page 99
Fig. 12. Location of major mineral deposit types discussed in the text .........Page 102
Table 1. Summary of major features of deposit groups discussed in text......Page 85
Pre-mineralization thermal evolution of the Palaeoproterozoic gold-rich Ashanti belt, Ghana......Page 114
Fig. 2. Succession of the different lithological units (top) and the main tectonic .........Page 116
Table 3. Heat-production rates and their standard deviations (s.d.) for Birimian and .........Page 119
Fig. 5. Temperature field (a) before and (b) after the D[sub(1)] tectonic phase, as .........Page 124
Fig. 7. Results of numerical experiments (P–T paths) for Birim sediments, compared with the .........Page 125
Table 1. Thermobarometric data (pressure and temperature estimates) for peak-metamorphism conditions at .........Page 117
Table 2. Thermal conductivity measurements of Birimian and Tarkwaian rock samples from the .........Page 118
Table 4. Main lithological units with associated density values and thermal properties. Density .........Page 121
Geodynamic processes that control the global distribution of giant gold deposits......Page 130
Fig. 1. Location of all known giant gold deposits. Symbol size relates to .........Page 131
Fig. 2. Schematic cross-section of an accretionary subduction zone, with a shaded area .........Page 133
Table 1. Definition of the consolidated domain classification.......Page 136
Fig. 4. Crustal sections of the type-examples of the six orogenic domains, .........Page 138
Table 3. General features of each domain classification.......Page 137
Table 4. Summary of fluid-type potential in each domain.......Page 139
Table 5. Giant gold deposits of the world in 2000 (see text for limitations).......Page 140
Table 6. Distribution of gold in giant deposits by tonnage and by number .........Page 141
Terrane and basement discrimination in northern Britain using sulphur isotopes and mineralogy of ore deposits......Page 144
Fig. 1. Pre-Atlantic configuration of the Caledonide orogen and adjacent regions, outlining .........Page 145
Fig. 2. Schematic vertical sections through the four terranes that were studied in detail. .........Page 146
Fig. 3. Summary bar charts of δ[sup(34)]S for Palaeozoic and older mineralization in Caledonide .........Page 154
Fig. 4. Sulphur isotope characteristics of granitoid-hosted mineralization in Caledonian terranes of northern .........Page 156
Table 1. Mean δ[sup(34)]S data for granitoids within four Caledonide terranes of northern Britain......Page 148
Table 2. Comparison of δ[sup(34)]S and granitoid-related mineralization styles between the British terranes and those .........Page 158
A reassessment of the tectonic zonation of the Uralides: implications for metallogeny......Page 164
Fig. 1. Proposed schematic map of tectonic domains of the Urals (modified from various .........Page 166
Fig. 2. Magnetic map and proposed correlations (map sourced from National Geophysical .........Page 167
Fig. 3. (a) Above: URSEIS section (after Echtler et al. 1996). EMSMF, .........Page 168
Fig. 4. Strike–slip faults of the Urals and major orogenic gold deposits .........Page 172
Fig. 5. Palinspastic reconstruction of the Urals with major mineral deposits located .........Page 173
The terrestrial record of stable sulphur isotopes: a review of the implications for evolution of Earth\'s sulphur cycle......Page 178
Fig. 1. Plot of δ[sup(33)]S versus δ[sup(34)]S for terrestrial sulphide and sulphate (data from .........Page 179
Fig. 2. Plots of (a)Δ[sup(33)]S versus δ[sup(34)]S (b) and Δ[sup(36)]S versus Δ[sup(33)]S for closed .........Page 180
Fig. 3. Plot of Δ[sup(33)]S versus time using published data (Farquhar et al. 2000a; .........Page 181
Fig. 4. Plots of (a) Δ[sup(33)]S versus Δ[sup(34)]S (b) and Δ[sup(36)]S versus Δ[sup(33)]S for .........Page 182
Fig. 5. Histograms of Δ[sup(33)]S for samples older than 2.45 Ga. The .........Page 183
Fig. 6. Plot of Δ[sup(33)]S versus Δ[sup(34)]S for published data for sulphide and sulphate .........Page 184
Fig. 7. Plot of Δ[sup(33)]S versus Δ[sup(34)]S for published data for sulphide and sulphate .........Page 185
Reactive iron enrichment in sediments deposited beneath euxinic bottom waters: constraints on supply by shelf recycling......Page 190
Fig. 1. Schematic diagram of the processes involved in enriching iron in deep-basin sediments.......Page 192
Fig. 2. Flux of iron required to be delivered to the deep basin .........Page 193
Fig. 3. Schematic model for the diffusive flux of diagenetically recycled iron .........Page 194
Table 1. Variation in the apparent first-order rate constant (k[sub(1)]) for Fe[sup(2)]+ .........Page 195
Fig. 6. Variations in the diffusive flux of diagenetically recycled iron with oxygenated .........Page 197
Fig. 7. Variations in the diffusive flux of diagenetically recycled iron with .........Page 198
Table 2. Ratios of shelf area (< 200 m depth) to deep (> 200 m) .........Page 199
Distinguishing biological from hydrothermal signatures via sulphur and carbon isotopes in Archaean mineralizations at 3.8 and 2.7 Ga......Page 206
Fig. 1. Map of Isua Greenstone Belt (3.7–3.8 Ga) showing the five structural .........Page 208
Fig. 3. Distributions of δ[sup(13)]C[sub(red)] for whole rocks from the IGB. The .........Page 210
Fig. 4. Map of the Belingwe Greenstone Belt (2.7 Ga) (modified from Grassineau et .........Page 214
Fig. 5. Vertical stratigraphic profiles of (a) δ[sup(34)]S and (b) δ[sup(13)C(red)] in the NERCMAR .........Page 215
Fig. 6. Detailed sulphur isotopic study of the BES50 sample, a core .........Page 216
Fig. 7. Comparison between δ[sup(34)]S of sulphide minerals in sedimentary sequences in (a) .........Page 218
Fig. 8. Comparison between δ[sup(13)]C[sub(red)] values for sedimentary rocks in (a) Early, .........Page 219
Table 1. δ[sup(13)]C[sub(red)] and δ[sup(34)]S ranges obtained in this study of the Isua .........Page 211
Diamond mega-placers: southern Africa and the Kaapvaal craton in a global context......Page 224
Table 1. Statistics for both diamond placer and primary deposits (for source see text)......Page 225
Fig. 2. Types of placers.......Page 226
Fig. 3. Examples of residual placers. (A) The internal, diamond-bearing, Kalahari basin .........Page 227
Fig. 4. Residual and transient type placer deposits in the eroded northern .........Page 228
Fig. 5. Distribution of transient placers along the lower Orange River valley. .........Page 229
Fig. 6. Diagrammatic section through the Lower Orange River terraces (Fig. 5) along with .........Page 230
Fig. 8. (A) Variations in diamond grade between kimberlites mined by De .........Page 232
Fig. 9. The convergence of orogens peripheral to the cratons of (A) .........Page 234
Fig. 10. Distribution of diamond-bearing kimberlites through time for the cratons of .........Page 235
Fig. 12. Means of concentrating and retaining diamonds on cratons. (A) Gradual .........Page 236
Fig. 14. The relationship between craton area, drainage basin area and the .........Page 238
Fig. 15. The importance of retaining diamonds on the craton in order to .........Page 239
Fig. 16. Large river systems known to have drained parts of the .........Page 240
Fig. 17. Distribution of kimberlites and alluvial deposits with respect to the .........Page 241
Fig. 18. The variation in diamond size along the SW African coast .........Page 242
Fig. 19. A reduced sediment input (cf. Fig. 21) enters a neutrally buoyant .........Page 243
Fig. 20. The changing diamond sizes along the Namibian coast. In B .........Page 244
Fig. 21. Soft Karoo cover is easily removed and deposited in two .........Page 245
Fig. 22. The area covered by possible sea-level fluctuations and the areal .........Page 246
Fig. 23. Summary of the requirements needed to form a diamond mega-placer.......Page 252
The formation of economic porphyry copper (–gold) deposits: constraints from microanalysis of fluid and melt inclusions......Page 258
Fig. 1. The principle of laser-ablation ICP mass spectrometric analysis of microscopic .........Page 260
Fig. 2. Reconstructed cross-section of the Farallón Negro Volcanic Complex at the .........Page 261
Fig. 3. View of the Bajo de la Alumbrera deposit in 1994, .........Page 262
Fig. 4. Typical rock, mineral and fluid inclusion relationships observed in porphyry .........Page 263
Fig. 5. Cu concentration (on a logarithmic scale) against silica content, comparing .........Page 264
Fig. 6. Schematic cartoon of a cylindrical porphyry copper orebody forming in .........Page 266
Fig. 7. (a) Cathodoluminescence (SEM-CL) image of quartz crystals in a main-stage stockwork .........Page 268
Fig. 8. (a) Log–log plot comparing the Cu and Au concentrations in .........Page 270
C......Page 276
G......Page 277
M......Page 278
S......Page 279
Z......Page 280