Gold metallogeny and exploration

TL;DR: In this paper, the authors discuss the distribution of gold in the Earth's crust and the characteristics of gold distribution in the lithosphere, including gold abundance in mafic and ultramafic rocks.

Abstract: Distribution of gold in the Earth's crust.- 1.1 Introduction.- 1.2 Gold in rock-forming minerals.- 1.3 Gold in igneous rocks.- 1.3.1 Introduction.- 1.3.2 General characteristics of gold distribution in the lithosphere.- 1.3.3 Gold abundance in mafic and ultramafic rocks.- 1.3.4 Gold in Precambrian rocks.- 1.3.5 Estimates of mantle gold abundance.- 1.3.6 Mafic volcanic rocks in non-orogenic environments.- 1.3.7 Mafic plutonic rocks in non-orogenic settings.- 1.3.8 Orogenic environments.- 1.4 Gold in sediments and sedimentary rocks.- 1.4.1 Introduction.- 1.4.2 Gold in sediments.- 1.4.3 Gold in clastic rocks.- 1.4.4 Gold in chemical sedimentary rocks.- 1.5 Gold in metamorphic rocks.- 1.5.1 Introduction.- 1.5.2 Regional metamorphism.- 1.5.3 Granitoid intrusions in metamorphic terranes.- 1.6 Concluding summary.- 1.7 Mineral data.- 1.7.1 Explanatory notes.- 1.7.2 The gold content of rock-forming minerals.- 1.7.3 The gold content of igneous rocks.- 1.7.4 The gold content of sediments and sedimentary rocks.- 1.7.5 The gold content of metamorphic rocks.- References.- The hydrothermal geochemistry of gold.- 2.1 Introduction.- 2.2 The inorganic chemistry of gold.- 2.2.1 Oxidation states.- 2.2.2 Relativistic effects.- 2.2.3 Coordination chemistry of Au(I).- 2.3 Gold complexing in hydrothermal solutions.- 2.3.1 Which complexes are important?.- 2.3.2 Halide complexes of gold(I).- 2.3.3 Hydrolysis.- 2.3.4 Hydrosulphido and sulphido complexes.- 2.3.5 Additional sulphur-containing ligands.- 2.3.6 Other ligands.- 2.4 Gold deposition.- 2.4.1 Boiling.- 2.4.2 Precipitation on colloid and mineral surfaces.- 2.5 Summary.- References.- 3 Archaean lode gold deposits.- 3.1 Introduction.- 3.1.1 Global distribution and economic significance.- 3.1.2 Genetic concepts.- 3.2 Nature of deposits.- 3.2.1 Introduction.- 3.2.2 Size and grade.- 3.2.3 Structural styles.- 3.2.4 Host rocks.- 3.2.5 Mineralization and wallrock alteration.- 3.2.6 Metal associations.- 3.3 Regional distribution.- 3.3.1 Heterogeneous distribution.- 3.3.2 Structural setting.- 3.3.3 Metamorphic setting.- 3.3.4 Spatial relationship to intrusive rocks.- 3.3.5 Timing of mineralization.- 3.3.6 Peak mineralization age.- 3.4 Constraints on genetic models.- 3.4.1 Introduction.- 3.4.2 Nature of ore fluids.- 3.4.3 Transport and deposition of gold.- 3.4.4 Fluid focusing.- 3.4.5 Source of fluid and ore components.- 3.5 Genetic models.- 3.6 Tectonic setting of gold mineralization.- 3.7 Potential exploration significance.- 3.8 Brief summary.- References.- 4 Phanerozoic gold deposits in tectonically active continental margins.- 4.1 Introduction.- 4.2 Distribution of Phanerozoic lode gold deposits in space and time.- 4.2.1 North America.- 4.2.2 South America.- 4.2.3 Australia New Zealand.- 4.2.4 Asia.- 4.2.5 Europe.- 4.2.6 Africa.- 4.3 Geological and geochemical characteristics.- 4.3.1 Host rocks.- 4.3.2 Structure.- 4.3.3 Ore morphology and textures.- 4.3.4 Mineralogy and paragenesis.- 4.3.5 Hydrothermal alteration.- 4.3.6 Elemental geochemistry and zoning.- 4.3.7 Fluid inclusions.- 4.3.8 Stable isotopes.- 4.3.9 Applications of Sr, Pb and Nd isotope ratios.- 4.4 Genetic models.- 4.5 Comparisons of Phanerozoic mesothermal deposits to other types of gold Mineralization.- 4.6 Conclusions.- References.- 5 Epithermal gold deposits in volcanic terranes.- 5.1 Introduction.- 5.2 Exploration case studies.- 5.2.1 Hishikari, Japan.- 5.2.2 Kelian, Kalimantan, Indonesia.- 5.2.3 Ladolam deposit, Lihir Island, Papua New Guinea.- 5.3 Environment of alteration and mineralization.- 5.3.1 Volcanic association.- 5.3.2 Structural controls.- 5.3.3 Wallrock alteration.- 5.3.4 Fluid inclusions and light stable isotopes.- 5.4 Active geothermal systems.- 5.5 Metal transport in epithermal systems.- 5.6 Physico-chemical conditions in the depositional regime.- 5.7 Epithermal deposits through geologic time.- 5.8 Exploration.- 5.9 Summary.- References.- 6 Intrusion-related gold deposits.- 6.1 Introduction.- 6.2 Geotectonic settings.- 6.3 Intrusion-hosted stockwork/disseminated deposits.- 6.3.1 Porphyry deposits.- 6.3.2 Other intrusion-hosted stockwork/disseminated deposits.- 6.4 Deposits in carbonate rocks.- 6.4.1 Skarn deposits.- 6.4.2 Carbonate-replacement deposits.- 6.5 Stockwork, disseminated and replacement deposits in non-carbonate rocks.- 6.6 Breccia-hosted deposits.- 6.7 Vein-type deposits.- 6.8 Deposit interrelationships and metal zoning.- 6.9 Genetic considerations.- 6.9.1 Magma type.- 6.9.2 Ore formation.- 6.10 Possible relationships with other gold deposit types.- 6.10.1 Epithermal deposits.- 6.10.2 Sediment-hosted deposits.- 6.10.3 Mother Lode-type deposits.- 6.11 Concluding remarks.- References.- 7 The geology and origin of Carlin-type gold deposits.- 7.1 Introduction.- 7.2 Classification of Carlin-type deposits.- 7.2.1 A historical perspective.- 7.2.2 Current perspectives.- 7.2.3 Relationship of Carlin-type deposits to polymetallic replacements.- 7.3 Regional geological and tectonic setting.- 7.3.1 Regional geological and tectonic setting in North America.- 7.3.2 Magmatism in western North America.- 7.3.3 Regional geological, tectonic, and magmatic settings in south-eastern China.- 7.4 Characteristics of the deposits.- 7.4.1 Nature of the host rocks.- 7.4.2 Structural setting of the deposits.- 7.4.3 Associated igneous rocks.- 7.4.4 Geochronology of the deposits.- 7.4.5 Alteration and metallization.- 7.4.6 Geochemistry of the deposits.- 7.4.7 Geophysical studies.- 7.4.8 Sizes, shapes, and grades of deposits.- 7.5 Ore deposit models.- 7.5.1 Published models.- 7.5.2 A speculative model.- 7.6 Exploration guidelines.- 7.7 Summary.- References.- 8 Auriferous hydrothermal precipitates on the modern seafloor.- 8.1 Introduction.- 8.2 Gold in seafloor polymetallic sulphide deposits.- 8.2.1 Mid-ocean ridges.- 8.2.2 Seamounts.- 8.2.3 Island-arc settings.- 8.2.4 Sedimented-rift environments.- 8.3 Mineralogy and geochemistry of gold in seafloor hydrothermal systems.- 8.4 Gold in sub-seafloor stockwork mineralization.- 8.5 Gold in hydrothermal plumes and associated metalliferous sediments.- 8.6 Transport and deposition of gold in seafloor hydrothermal systems.- 8.6.1 The chemistry of seafloor hydrothermal fluids in volcanic environments.- 8.6.2 The chemistry of seafloor hydrothermal fluids in sedimentary environments.- 8.6.3 The solubility of gold in seafloor hydrothermal fluids.- 8.6.4 The flux of gold in seafloor hydrothermal fluids.- 8.7 Secondary enrichment of gold in supergene sulphides and gossans.- 8.8 Gold in ancient seafloor hydrothermal systems.- 8.8.1 Volcanogenic massive sulphides.- 8.8.2 Metalliferous sediments.- 8.8.3 Gold deposits in auriferous chemical and clastic sediments.- References.- 9 Ancient placer gold deposits.- 9.1 Introduction.- 9.2 Geological setting.- 9.2.1 Pongola.- 9.2.2 Dominion.- 9.2.3 Witwatersrand.- 9.2.4 Ventersdorp.- 9.2.5 Transvaal.- 9.2.6 Jacobina.- 9.2.7 Moeda.- 9.2.8 Tarkwa.- 9.3 The palaeosurfaces.- 9.3.1 Areal dimensions.- 9.3.2 Topographic relief.- 9.3.3 Stratigraphic position.- 9.3.4 Correlation.- 9.4 The placer sediments.- 9.4.1 Gravel and sand fraction.- 9.4.2 Geometry.- 9.4.3 Deposition.- 9.4.4 Heavy mineral fraction.- 9.4.5 Mineralogy.- 9.4.6 Kerogen.- 9.5 Metamorphism.- 9.6 Structural control.- 9.7 Summary.- References.- 10 Geochemical exploration for gold in temperate, arid, semi-arid, and rain forest terrains.- 10.1 Introduction.- 10.2 Geochemical signatures of gold mineralization.- 10.2.1 Attributes of bedrock mineralization.- 10.2.2 Supergene cycle of gold.- 10.2.3 Transposition of the primary characteristics to the supergene environment.- 10.3 Examples and case histories.- 10.3.1 Introduction.- 10.3.2 Temperate terrains.- 10.3.3 Arid and semi-arid terrains.- 10.3.4 Rain forest environments.- 10.4 Operating procedures.- 10.4.1 Sampling and sample preparation.- 10.4.2 Sample analysis.- 10.5 Alternative sampling techniques.- 10.5.1 Lithogeochemistry.- 10.5.2 Heavy-mineral concentrate geochemistry.- 10.5.3 Hydrogeochemistry.- 10.5.4 Atmogeochemistry.- 10.5.5 Biogeochemistry.- 10.6 Conclusions.- References.- 11 Geochemical exploration for gold in glaciated terrain.- 11.1 Introduction.- 11.2 Glacial dispersal.- 11.3 Glacial stratigraphy and ice-movement directions.- 11.4 Sampling and analytical methods.- 11.5 Occurrence of gold in till and soil and the effects of weathering.- 11.6 Drift prospecting for gold.- 11.7 Source of placer gold in glaciated terrains.- 11.8 Conclusions and future trends.- References.- 12 Geophysical exploration for gold.- 12.1 Introduction.- 12.2 Geological and geophysical models.- 12.3 Exploration strategy and methods.- 12.3.1 Reconnaissance.- 12.3.2 Regional.- 12.3.3 Detailed.- 12.4 Examples.- 12.4.1 Veins, stockworks and lodes.- 12.4.2 Skarns.- 12.4.3 Auriferous volcanogenic sulphides.- 12.4.4 Auriferous granitoids.- 12.4.5 Disseminated deposits in igneous, volcanic and sedimentary units.- 12.4.6 Palaeoplacers.- 12.4.7 Placers.- 12.5 Conclusions.- 12.6 Glossary of geophysical terms.- References.- 13 Economics of gold deposits.- 13.1 Introduction.- 13.2 Market setting.- 13.3 Gold-mine production.- 13.3.1 World-wide trends.- 13.3.2 Brazil.- 13.3.3 United States.- 13.3.4 Australia.- 13.3.5 South Africa.- 13.3.6 Canada.- 13.3.7 The 1980s.- 13.4 Economic evaluation of gold deposits.- 13.4.1. The decision process.- 13.4.2 Economic evaluation techniques.- 13.4.3 Estimation of cash flow.- 13.4.4 Cash-flow criteria.- 13.4.5 The cost of capital.- 13.4.6 DCF criteria.- 13.5 Characteristics of economic gold deposits.- 13.5.1 Canadian case study.- 13.5.2 Presentation format.- 13.5.3 Deposit input variables.- 13.5.4 Cash-flow criteria.- 13.5.5 DCF criteria.- 13.6 Conclusion.- References.