Giant Metallic Deposits (eBook)

Preface 4
Contents 6
Context, explanations, abbreviations, units 12
Book Context and Background 12
Geological ages 14
Miscellaneous abbreviations 14
Tonnage units and abbreviations 15
Pure metals converted from various compounds 15
1 Civilization based on metals 16
1.1. Past and present sources ofindustrial metals 16
1.1.1. Introduction 16
1.1.2. History of metal supplies 16
1.1.3. Present metals supplies 19
1.2. Metal prices 21
1.3. Future metal supplies 24
1.3.1. How much metals will be needed? 25
1.3.2. Reducing demand for “new” metals 30
1.3.3. Où sont les métaux por avenir?Future ore deposits, conventional andnon-conventional 33
1.4. Conclusion: future supplies ofmetals and giant deposits 40
2 Data on metallic deposits and magnitudecategories: the giant and world class deposits 48
2.1. Data sources and databases 48
2.2. Giant and world class ore deposits:definition and characteristics 51
2.3. Dimension, complexity andhierarchy of metallic deposits, district 57
2.4. The share of “giant” metalaccumulations in global metal supplies 60
3 From trace metals to giant deposits 70
3.1. Introduction 70
3.2. Extraterrestrial metals and oresresulting from meteorite impact 71
3.3. Lithospheric evolution and oreformation related to geochemicalbackgrounds 74
4 Geological divisions that contain ore giants:introduction and the role of mantle 80
4.1. Earth’s geodynamics, platetectonics, and metallogenesis 81
4.2. The Earth’s mantle and its role interrestrial (crustal) lithogenesis andmetallogenesis 82
4.3. Organization of chapters in thedescriptive Part II of this book 87
5 Oceans and young island arc systems 92
5.1. Oceanic crust, ocean floor 93
5.2. Intraplate volcanic islands,seamounts and plateaus on oceaniccrust 98
5.3. Sea water as a source of metals 98
5.4. Ocean floor sediments 99
5.5. Active to “young” (pre-orogenic)convergent plate margins on sea floorand in islands 101
5.6 Island arc metallogeny and giantdeposits 102
5.7. Island arc-trench subenvironmentsand ore formation 105
5.8. Magmatic (volcano-plutonic)systems in island arcs 107
5.9 Back-arcs (marginal seas), interarcs,and other extensional basins 114
5.10. Magnetite beach sands 118
6 Andean-type convergent continental margins(upper volcanic-sedimentary level) 120
6.1 Introduction 120
6.2. Metals fluxing and metallogenesis 124
6.2.1. Ores in predominantly continentalsediments 124
6.2.2. Ores in contemporaneous and“young” subaerial volcanics 129
6.2.3. Ores in predominantly andesiticancient convergent continental margins 135
6.2.4. “Red beds” in Andean margins 137
6.2.5. Ores in Andean margin rhyolites 138
6.3. Geothermal systems on land and in theshallow subsurface 140
6.3.1. Hot spring deposits 142
6.4. High-sulfidation epithermal ores 143
6.4.1. Low-grade (“bulk”), low-sulfide Au–Agdeposits 144
6.4.2. Transition to sulfides-rich highsulfidationAu–Ag systems 147
6.4.3. Diatreme-dome complexes withenargite-gold centers surrounded by pyriteand Zn–Pb–Ag carbonate replacements 149
6.4.4. Combined high sulfidation / porphyryCu–Au–Ag systems 151
6.5. Low sulfidation (LS) deposits 156
6.5.1. Au-dominated low-sulfidation ores 158
6.5.2. Au–(Te)> Ag alkaline association
6.5.3. Bonanza Ag> >
6.5.4. Epithermal to mesothermal Pb, Zn,(Cu), Au, Ag deposits 169
6.5.5. Other epithermal deposits: Mo, W, Bi,U, As, Sb, Te, Hg Mn172
6.5.6. Low sulfidation deposits as part of asystem: other related mineralization 174
6.5.7. “Bolivian-type” porphyry Sn-bonanzaAg composite association 175
7 Cordilleran granitoids in convergent continentalmargins (lower, plutonic levels) 180
7.1. Introduction 180
7.2. Metallogeny 181
7.3. Porphyry deposits: Cu, Cu–Mo, Au 184
7.3.1. General and calc-alkaline 184
7.3.2. Breccias in porphyry systems 189
7.3.3. Evolution of magmatic-hydrothermal“porphyry” systems, alterations, ores 193
7.3.4. Alkaline (diorite model) porphyry Cu–(Au) deposits 196
7.3.5. Combined porphyry Cu (Mo, Au) andskarn deposits 203
7.3.6. Precambrian porphyry-style Cu, Mo,Au deposits 208
7.3.7. Supergene modification of porphyrydeposits 208
7.3.9. Porphyry Cu-(Mo, Au) deposits:global distribution and description 217
7.4. Stockwork molybdenum deposits 238
7.4.1. Differentiated monzogranite Mo suite 240
7.4.2. High-silica rhyolite suite (Climax type) 242
7.4.4. Stockwork Mo in the alkaline “rift”association 244
7.4.5. Mo-dominated skarn deposits 244
7.5. Stockwork, vein and skarn Mo-W-Bi 247
7.6. Scheelite skarn deposits 249
7.7. Cordilleran Pb–Zn–Ag (Cu) deposits 252
7.7.1. High-temperature Zn, Pb, Agreplacements in carbonates 252
7.7.2. Mesothermal Pb–Zn–Ag (Sb) veins 258
7.8. Hydrothermal Fe, Mn, Sb, Sn, B, U,Th deposits in, and associated with,Cordilleran granitoids 264
7.9. Carlin-type micron-size Au (As, Hg,Sb, Tl) deposits 266
7.9.1. “Invisible gold” in the Great Basin 268
7.9.2. “Carlin-type” gold outside the U.S.A. 272
8 Intracratonic (intraplate) orogens, granites,hydrothermal deposits 274
8.1. Introduction 274
8.1.1. Granitoids in orogenic setting 276
8.2. Massif anorthosite association: Fe–Ti–V and Ni–Cu deposits 282
8.3. Ores closely associated withgranites & pegmatites
8.3.1. Rare metals pegmatites 285
8.3.2. Zr, Nb, Ta, Y, REE, Th, Be associationin peralkaline granites 290
8.3.3. Uraniferous leucogranites, aplites,pegmatites 292
8.3.4. Granite-related wolframite deposits(Jiangxi-type) 293
8.3.5. Granite-related tin deposits 295
8.3.6. Cassiterite regoliths and placers 301
8.3.7. Multi-metal zoned Sn, Mo, W, Bi, Be,Pb, Zn skarn-greisen-vein systems 303
8.3.8. Hydrothermal U deposits 308
8.4. Mesothermal gold 312
8.4.1. Intrusion (“granite”)-related Au veins,stockworks, disseminations 315
8.4.2. Gold skarns 316
8.4.3. Transition of granite-related to(syn)orogenic Au deposits 317
8.5. Dominantly orogenic metamorphichydrothermalAu deposits 323
8.5.1. (Syn)orogenic gold veins andstockworks 323
8.6. Gold placers 331
8.7. (Syn)orogenic Sb & Hg deposits
8.7.1. Antimony deposits 334
8.7.2. Mercury deposits 339
8.8. Pb, Zn, Ag veins and replacements 343
9 Volcano-sedimentary orogens 352
9.1. Introduction 352
9.1.1. Growth and evolution of compositevolcano-sedimentary orogens exemplifiedby the Canadian Cordillera 355
9.2. Ophiolite allochthons, melangesand alpine serpentinites 357
9.3. Oceanic successions 363
9.4. Mafic and bimodal marine volcanicsedimentarysuccessions 364
9.4.1. VMS (volcanic-associated massivesulfide) deposits 365
9.4.2. Sedimentary rocks-hosted Fe, Cu, Zn,Pb ores 377
9.4.3. Au–Ag deposits 377
9.5. Differentiated mafic-ultramaficintrusions (Alaska-Urals type) 378
9.6. Calc-alkaline and shoshoniticvolcanic-sedimentary successions 380
9.7. Miscellaneous metallic ores 385
10 Precambrian greenstone-granite terrains 386
10.1. Introduction 386
10.1.1. Abitibi Subprovince (greenstonebelt), Canadian Shield 387
10.2. Komatiitic association and Ni ores 391
10.3. Early Proterozoic paleo-ophiolites 398
10.4. Mafic and bimodal greenstonesequences: Fe ores in banded ironformations 399
10.5 VMS deposits in bimodal andsequentially differentiated volcanicsedimentaryassociation 402
10.6. Granitoid plutons in greenstonesetting and older Precambrian“porphyry” deposits 410
10.7. (Syn)orogenic hydrothermal Au-(As, Sb, Cu) in greenstone terrains 412
10.7.1. Introduction to orogenic deposits 412
10.8. Synorogenic Cu (U, Ni, Au, Ag)deposits overprinting greenstone belts 431
10.9. Ores in late orogenic sedimentaryrocks in greenstone belts 432
11 Proterozoic-style intracratonic orogens andbasins: extension, sedimentation, magmatism 436
11.1. Introduction 436
11.2. Metallogeny and giant deposits 439
11.3. Sedex concepts applied toProterozoic Pb–Zn–Ag deposits 444
11.4. Strata controlled Proterozoiccopper deposits in (meta)sedimentaryrocks 448
11.5. Au and U in quartz-richconglomerates (Witwatersrand-type) 456
11.6. Fe in Superior-type banded ironformations (BIF) 465
11.7. Fe (BIF) and Mn in diamictites 477
11.8. Bedded and residual Mn deposits 480
11.9. Miscellaneous, complex Zn, Pb,Cu, Co, V, Ag, Ge, Ga, (U) deposits inProterozoic sedimentary rocks 483
11.10. Oxidic (nonsulfide) Zn and Pbdeposits 486
11.11. Unconformity uranium deposits 488
11.12. Hydrothermal Fe oxide depositswith Cu, or U, or Au, or REE: the IOCGgroup that includes Olympic Dam 491
12 Rifts, paleorifts, rifted margins, anorogenicand alkaline magmatism 504
12.1. Introduction 504
12.2. Young rifts, hydrothermal activity 507
12.3. Mantle plumes, continentalbreakup, rifted continental margins 509
12.3.1. Mantle plumes and hot spots 509
12.3.2. Rifted (Atlantic-type) continentalmargins 509
12.3.3. Intraplate and rift margin mafic tobimodal magmatism 511
12.4. Plateau (flood) basalts 513
12.4.1. Ni–Cu sulfide deposits in intrusionsassociated with plateau basalt provinces 513
12.4.2. Lateritic bauxite on basalt 518
12.5. Diabase, gabbro, rare peridotitedikes and sills 519
12.6. Bushveld-style layered intrusions 522
12.7. Sudbury complex Ni, Cu, Co, PGE,Ontario: an enigma related to meteoriteimpact 535
12.8. Alkaline magmatic association 541
12.8.1. Introduction 541
12.8.2. Alkaline metallogeny and giantdeposits 543
12.8.3. Alkaline volcanic and subvolcaniccenters 545
12.8.4. Nepheline syenite-dominatedintrusions 545
12.8.5. Alkaline pyroxene-nepheline seriesand alkaline ultramafics 549
12.9. Carbonatites 553
13 Sedimentary associations and regolith 562
13.1. Introduction 562
13.2. Marine clastics 564
13.2.1. Ore formation 565
13.2.2. Detrital (clastic) ores: coastal andshelf heavy mineral sands and paleoplacersof Fe, Ti, Zr, REE, Th 567
13.3. Combined clastic and chemicalbedded sedimentary deposits 570
13.3.1. Particulate (oolitic) ironstones 570
13.3.2. Bedded Mn deposits (Phanerozoic 573
13.3.3. Mineralized carbonaceous pelites(“black shales”) 576
13.3.4. Phosphorite-black shale association 581
13.3.5. Cu, Ag (Pb, Zn, Au, PGE) associatedwith reduced marine units above “redbeds”(Kupferschiefer or copper shale-type) 584
13.3.6. Sedex Pb-Zn-Ag deposits in basinalshale near carbonate platform 588
13.4. Marine carbonates and evaporites 594
13.4.1. Introduction 594
13.4.2. Warm-current (Florida-type)phosphorites and their uranium enrichment 598
13.4.3. Bedded Mn deposits in “basinal”(reduced) carbonates 599
13.4.4. Low-temperature Zn–Pb deposits incarbonates 600
13.4.5. Discordant (vein) Zn–Pb orebodiesof “MVT affiliation” 609
13.4.6. Stratabound cinnabar deposits incarbonates 610
13.4.7. Metallic ores in karst on carbonates 611
13.5. Marine evaporites and ores 612
13.6. Hydrocarbons as a source ofmetals 614
13.7. Ores in regolith and continentalsediments 615
13.7.1. Introduction 615
13.7.2. Glaciation and ores in glaciogenic(cryogenic) materials and structures,related talus and glaciofluvial deposits 616
13.7.3. Humid tropical regoliths 617
13.7.4. Supergene Cu ores andleaching/reprecipitation profiles 624
13.7.5. Paleo-regoliths, paleosols and basalsequences at unconformities 627
13.7.6. Humid alluvial environments: placerdeposits 631
13.7.7. Lakes and lacustrine sequences 632
13.7.8. Arid regoliths and sediments 634
13.7.9. Sandstone-dominated continentalsequences: “grey” and “red” 637
13.7.10. Metals recoverable from coal 638
13.7.11. Infiltrations from meteoric waters:“sandstone-U (V)” deposits 639
13.7.12. Cu-sandstone deposits in red andgrey (varicolored) beds 645
13.7.13. Sandstone-Pb (Zn) deposits 646
13.8. Anthropogenic metal sources 648
14 Higher-grade metamorphic associations 652
14.1. Introduction 652
14.2. Metallogeny 654
14.3. High-grade associations and ores 656
14.4. High-grade metamorphosedbanded iron formations (BIF) 659
14.5. Pb–Zn–Ag sulfide orebodies ingneiss > >
14.6. Zn, Pb sulfides and Zn–Mn oxidesin marble and Ca–Mg silicate hosts 664
14.7. Zn, Cu, Pb sulfide deposits ingneiss, schist, marble (meta-VMS?) 667
14.8. Disseminated Cu sulfide depositsin gneiss, schist and marble 669
14.9. Scheelite, uranian phosphates,magnesite, borates in marble and Ca–Mg silicate gneiss 672
14.10. High-grade metamorphic mafic-(ultramafic)- association 673
14.11. Retrograde metamorphosed andmetasomatised mineralized structures 679
15 Giant deposits in geological context 688
15.1. Origin of giant deposits 688
15.1.1. Genetic coding and ore varieties 689
15.1.2. Giant deposits and their genetic andhost rock associations 697
15.2. Giant metallic deposits:geotectonic setting 704
15.3. Giant metal accumulations ingeological time 705
15.4. Why ore “giants” are so big andare where they are? 710
16 Giant deposits: industry, economics, politics 714
16.1. Historical background 714
16.2. Giant deposits and corporations 718
16.3. “Ore giants” and economics 723
16.4. Investment risk in exploration andmining 728
17 Finding or acquiring giant deposits 736
17.1. Introduction 736
17.2. History of discovery of giant oredeposits/districts 743
17.3. Acquiring giant deposits fortomorrow 753
17.3.1. Acquisition of an existing deposit 754
17.3.2. Finding “ore giants” using geology 755
Epilogue 760
References 766
Index of mineral deposits 838
Subject Index 846
Appendix: Database of significant metalaccumulations 859