Potassic Igneous Rocks and Associated Gold-Copper Mineralization

1 Introduction.- 1.1 Preamble: Potassic Igneous Rocks and Their Importance.- 1.2 Scope of Book.- 2 Definitions and Nomenclature.- 2.1 Historical Perspective of Potassic Igneous Rocks.- 2.2 Potassic Igneous Rocks as an Umbrella Term.- 2.3 Shoshonites.- 2.4 Shoshonitic and Alkaline Lamprophyres.- 2.5 Ultrapotassic Rocks.- 2.5.1 Introduction.- 2.5.2 Lamproites.- 2.5.3 Kamafugites.- 2.5.4 Orogenic Ultrapotassic Rocks.- 2.6 Group II Kimberlites.- 2.7 Potassic Igneous Rocks as Considered in this Book.- 2.8 Field Recognition of Potassic Igneous Rocks.- 3 Tectonic Settings of Potassic Igneous Rocks.- 3.1 Introduction.- 3.2 Tectonic Settings of Potassic Igneous Rocks.- 3.2.1 Continental Arc.- 3.2.2 Postcollisional Arc.- 3.2.3 Oceanic (Island) Arc.- 3.2.4 Within-Plate.- 3.2.5 Problems with Tectonic Classification.- 3.3 History of Discrimination of Tectonic Setting by Geochemical Means.- 3.4 Erection of Databases SHOSH1 and SHOSH2.- 3.5 Discrimination of Tectonic Setting by Multivariate Statistical Methods.- 3.6 Discrimination via Simple Geochemical Diagrams.- 3.7 Theoretical Basis for Discrimination Between Potassic Igneous Rocks in Different Tectonic Settings.- 3.8 Conclusions.- 4 Selected Type-Localities of Potassic Igneous Rocks from the Five Tectonic Settings.- 4.1 Roman Province (Italy): Example from a Continental Arc Setting.- 4.1.1 Introduction.- 4.1.2 Regional Geology.- 4.1.3 Mineralogy and Petrography of the Potassic Igneous Rocks.- 4.1.4 Geochemistry of the Potassic Igneous Rocks.- 4.2 Kreuzeck Mountains, Eastern Alps (Austria): Example from a Postcollisional Arc Setting.- 4.2.1 Introduction S.- 4.2.2 Regional Geology.- 4.2.3 Mineralogy and Petrography of the Lamprophyres.- 4.2.4 Geochemistry of the Lamprophyres.- 4.3 Northern Mariana Arc (West Pacific): Example from an Initial Oceanic Arc Setting.- 4.3.1 Introduction.- 4.3.2 Regional Geology.- 4.3.3 Mineralogy and Petrography of the Potassic Igneous Rocks.- 4.3.4 Geochemistry of the Potassic Igneous Rocks.- 4.4 Vanuatu (Southwest Pacific): Example from a Late Oceanic Arc Setting.- 4.4.1 Introduction.- 4.4.2 Regional Geology.- 4.4.3 Mineralogy and Petrography of the Potassic Igneous Rocks.- 4.4.4 Geochemistry of the Potassic Igneous Rocks.- 4.5 African Rift Valley (Rwanda, Uganda, Zaire): Example from a Within-Plate Setting.- 4.5.1 Introduction.- 4.5.2 Regional Geology.- 4.5.3 Mineralogy and Petrography of the Potassic Igneous Rocks.- 4.5.4 Geochemistry of the Potassic Igneous Rocks.- 5 Primary Enrichment of Precious Metals in Potassic Igneous Rocks.- 5.1 Introduction.- 5.2 Theoretical Discussion.- 5.3 Case Study: Potassic Alkaline Lamprophyres with Elevated Gold Concentrations from the Karinya Syncline, South Australia.- 5.3.1 Introduction.- 5.3.2 Regional Geology and Tectonic Setting.- 5.3.3 Mineralization in the Vicinity of the Lamprophyres.- 5.3.4 Nature of the Lamprophyres.- 5.3.5 Petrology and Geochemistry of the Lamprophyres.- 5.3.6 Precious Metal Abundance and Significance.- 5.4 Comparison of Precious Metal Abundances for Lamprophyres from the Karinya Syncline and Kreuzeck Mountains.- 6 Direct Associations Between Potassic Igneous Rocks and Gold-Copper Deposits.- 6.1 Direct Associations in Specific Tectonic Settings: Introduction.- 6.2 Erection of Database GOLD 1.- 6.3 Late Oceanic Arc Associations.- 6.3.1 Ladolam Gold Deposit, Lihir Island, Papua New Guinea.- 6.3.2 Emperor Gold Deposit, Viti Levu, Fiji.- 6.3.3 Dinkidi Copper-Gold Deposit, Didipio, Phillipines.- 6.3.4 Goonumbla Copper-Gold Deposit, New South Wales, Australia.- 6.4 Continental Arc Associations.- 6.4.1 Bajo de la Alumbrera Copper-Gold Deposit, Catamarca Province, Argentina.- 6.4.2 Bingham Copper Deposit, Utah, USA.- 6.4.3 El Indio Gold Deposit, Chile.- 6.4.4 Twin Buttes Copper Deposit, Arizona, USA.- 6.5 Postcollisional Arc Associations.- 6.5.1 Grasberg Copper-Gold Deposit, Indonesia.- 6.5.2 Misima Gold Deposit, Misima Island, Papua New Guinea.- 6.5.3 Porgera Gold Deposit, Papua New Guinea.- 6.6 Synthesis of Direct Genetic Associations.- 7 Indirect Associations Between Lamprophyres and Gold-Copper Deposits.- 7.1 Introduction.- 7.2 Shoshonitic Lamprophyres with Elevated Gold Concentrations from the Goodall Gold Deposit, Northern Territory, Australia (Proterozoic).- 7.2.1 Introduction.- 7.2.2 Regional Geology.- 7.2.3 Nature of Mesothermal Gold Mineralization.- 7.2.4 Mineralogy of the Lamprophyres.- 7.2.5 Geochemistry of the Lamprophyres.- 7.2.6 Direct or Indirect Link Between Potassic Lamprophyres and Mineralization.- 7.3 Shoshonitic Lamprophyres from the Tom’s Gully Gold Deposit, Northern Territory, Australia (Proterozoic).- 7.3.1 Introduction.- 7.3.2 Regional Geology.- 7.3.3 Nature of Mesothermal Gold Mineralization.- 7.3.4 Petrology and Geochemistry of the Lamprophyres.- 7.3.5 Indirect Link Between Lamprophyres and Gold Mineralization.- 7.4 Shoshonitic Lamprophyres from the Eastern Goldfields, Yilgarn Block, Western Australia (Archaean).- 7.4.1 Introduction.- 7.4.2 Regional Geology.- 7.4.3 Nature of Mesothermal Gold Mineralization.- 7.4.4 Lamprophyres and Their Association with Mineralization.- 7.4.5 Petrology and Geochemistry of the Lamprophyres.- 7.5 Shoshonitic Lamprophyres from the Superior Province, Canada (Archaean).- 7.5.1 Introduction.- 7.5.2 Nature of Mesothermal Gold Mineralization.- 7.5.3 Lamprophyres and Their Association with Mineralization.- 7.5.4 Petrology and Geochemistry of the Lamprophyres.- 7.6 Indirect Link Between Lamprophyres and Archaean Gold Mineralization.- 7.7 Synthesis of Indirect Associations.- 8 Halogen Contents of Mineralized Versus Unmineralized Potassic Igneous Rocks.- 8.1 Introduction.- 8.2 Erection of Database MICA1.- 8.3 Discussion.- 8.3.1 Behaviour of Halogens in Magmatic Hydrothermal Systems.- 8.3.2 Halogen Contents of Mica in Potassic Igneous Rocks.- 8.3.3 Significance of Halogen Data.- 9 Implications for Mineral Exploration.- 9.1 Introduction.- 9.2 Area Selection.- 9.2.1 Composition of Host Rocks.- 9.2.2 Tectonic Setting.- 9.3 Prospect Evaluation.- 9.3.1 Favourable Tectonic Elements on the Prospect Scale.- 9.3.2 High Oxidation State of the Magmas.- 9.3.3 Elevated Halogen Contents of the Magmas.- 10 Characteristics of Some Gold-Copper Deposits Associated with Potassic Igneous Rocks.- 10.1 Abbreviations.- 10.2 Tables of Deposit Characteristics.- 10.2.1 Andacollo, Chile.- 10.2.2 Bajo de la Alumbrera, Catamarca Province, Argentina.- 10.2.3 Bingham, Utah, USA.- 10.2.4 Cadia, New South Wales, Australia.- 10.2.5 Choquelimpie, Chile.- 10.2.6 Cripple Creek, Colorado, USA.- 10.2.7 Dinkidi, Didipio, Philippines.- 10.2.8 El Indio, Chile.- 10.2.9 Emperor, Viti Levu, Fiji.- 10.2.10 Goonumbla, New South Wales, Australia.- 10.2.11 Grasberg, Indonesia.- 10.2.12 Kirkland Lake, Superior Province, Canada.- 10.2.13 Ladolam, Lihir Island, Papua New Guinea.- 10.2.14 Maricunga Belt, Chile.- 10.2.15 Misima, Misima Island, Papua New Guinea.- 10.2.16 Mount Kare, Papua New Guinea.- 10.2.17 Mount Morgans, Eastern Goldfields, Western Australia.- 10.2.18 Ok Tedi, Papua New Guinea.- 10.2.19 Porgera, Papua New Guinea.- 10.2.20 Summitville, Colorado, USA.- 10.2.21 Tom’s Gully, Northern Territory, Australia.- 10.2.22 Twin Buttes, Arizona, USA.- 10.2.23 Wiluna, Eastern Goldfields, Western Australia.- 10.2.24 Woodlark Island, Papua New Guinea.- References.