Hydrothermal Mineral Deposits, Softcover reprint of the original 1st ed. 1992
Principles and Fundamental Concepts for the Exploration Geologist

This book is intended primarily for exploration geologists and post­ graduate students attending specialist courses in mineral exploration. Exploration geologists are engaged not only in the search for new mineral deposits, but also in the extension and re-assessment of existing ones. To succeed in these tasks, the exploration geologist is required to be a "generalist" of the Earth sciences rather than a specialist. The exploration geologist needs to be familiar with most aspects of the geology of ore deposits, and detailed knowledge as well as experience play an all important role in the successful exploration for mineral commodities. In order to achieve this, it is essential that the exploration geologist be up to date with the latest developments in the evolution of concepts and ideas in the Earth sciences. This is no easy task, as thousands of publications appear every year in an ever increasing number of journals, periodicals and books. For this reason it is also difficult, at times, to locate appropriate references on a particular mineral deposit type, although this problem is alleviated by the existence of large bibliographic data bases of geological records, abstracts and papers on computers. During my teaching to explorationists and, indeed, during my years of work as an explorationist, the necessity of having a text dealing with the fundamental aspects of hydrothermal mineral deposits has always been compelling. Metallic mineral deposits can be categorised into three great families, namely: (I) magmatic; (2) sedimentary and residual; (3) hydrothermal.

I Introduction.- I Nature and Types of Hydrothermal Solutions and Systems.- 1 Water and Solutions.- 1.1 Introduction.- 1.2 Water: Its Origin and Significance.- 1.2.1 Planetary Evolution and the Origin of Water.- 1.2.2 Water — Past and Present.- 1.2.3 Water in Subduction Zones.- 1.2.4 Water in the Crust.- 1.3 Solutions.- 1.4 Solubility and Boiling.- 1.5 Acid-Base Nomenclature.- 1.6 Structure of Water — Hydrolysis and Hydration.- 1.7 Redox Potential (Eh).- 1.8 Chemical Potential, Chemical Activity and Fugacity.- References.- 2 Hydrothermal Solutions.- 2.1 Introduction.- 2.2 Water of Hydrothermal Solutions.- 2.3 Oxygen and Hydrogen Isotope Systematics of Hydrothermal Fluids.- 2.4 Fluid Inclusions.- 2.5 Dissolved Constituents and Metals Partitioning into Hydrothermal Solutions.- 2.5.1 Partitioning of Metallic Elements into Hydrothermal Solutions.- 2.6 Metal Transport.- 2.6.1 Complex Ions and Ligands.- 2.6.2 Complex Ions in Hydrothermal Solutions.- 2.7 Metal Deposition.- References.- 3 Hydrothermal Systems.- 3.1 Introduction.- 3.2 Definition and Types.- 3.3 Magmatic Hydrothermal Systems Related to Shallow and Deep-Seated Plutonism.- 3.4 Magmatic-Meteoric Hydrothermal Systems, Related to Volcano-Plutonic and Volcanic Complexes.- 3.4.1 Magmatic Hydrothermal Systems.- 3.4.2 Predominantly Meteoric Hydrothermal (Geothermal) Systems.- 3.4.3 Hot Water-Dominated and Vapour-Dominated Hydrothermal Systems.- 3.4.4 Hot Springs, Mud Pools, Geysers, Crater Lakes and Fumaroles.- 3.5 Sub-Sea-Floor Hydrothermal Systems: Spreading Centres and Island Arcs.- 3.5.1 Hydrothermal Systems in Spreading Centres.- 3.5.2 Hydrothermal Systems in Submarine Volcanic Centres.- 3.6 Rift-Associated Hydrothermal Systems in Sedimentary Basins.- 3.6.1 Hydrothermal Systems.- 3.6.2 Hydrothermal Systems in Modern Rift Settings.- 3.7 Hydrothermal Systems of Metamorphic and Crustal Origin.- 3.7.1 Metamorphism, Metasomatism, Dewatering of Rock Sequences and Fluid Generation.- 3.7.2 Fluid Pressure, Metamorphic Porosity, Impermeable Barriers and Hydraulic Fracturing.- 3.7.3 Metamorphic Hydrothermal Systems.- 3.7.4 Fluid Paths: Faults, Shear Zones and Thrust Faults.- 3.7.5 Fluids in Subduction Zones.- References.- 4 Hydrothermal Alteration.- 4.1 Introduction.- 4.2 Hydrogen Ion Metasomatism and Base Exchange.- 4.2.1 Chemical Processes Related to Hydrogen Ion Metasomatism.- 4.3 Styles and Types of Hydrothermal Alteration.- 4.3.1 Styles of Alteration.- 4.3.2 Types of Alteration.- 4.3.3 Other Types of Alteration.- 4.4 Quantification and Monitoring of Hydrothermal Alteration Processes — Data Presentation.- 4.4.1 Rare Earths Elements in Hydrothermal Alteration Processes.- 4.5 Oxygen and Hydrogen Isotope Systematics.- 4.6 Metamorphism of Hydrothermally Altered Rocks.- 4.7 Detection of Hydrothermal Alteration by Spectral Remote Sensing.- References.- II Crustal Evolution, Global Tectonics, Hydrothermal Mineral Deposits and Mineral Exploration — Geotectonic and Metallogenic Analysis of Orogenic Belts.- 5 Crustal Evolution, Global Tectonics and Mineral Deposits.- 5.1 Introduction.- 5.2 Tectonic Phases in the Earth’s Geological Evolution and Related Metallogeny.- 5.2.1 The Archean Eon: Phase of Microplate Tectonics.- 5.2.2 The Proterozoic Eon: Phase of Intraplate Tectonics.- 5.2.3 The Phanerozoic Eon: Phase of Macroplate Tectonics, Sea Floor Spreading and Continental Drift.- 5.2.4 Conclusions.- References.- 6 Geological Processes and Hydrothermal Mineralisation in Plate Tectonic Settings — Mineral Exploration.- 6.1 Introduction.- 6.2 Extensional Plate Tectonics.- 6.2.1 Mid-Ocean Spreading Centres.- 6.2.2 Intracontinental Rifts.- 6.2.3 Passive Continental Margins and Interior Basins.- 6.3 Compressional Plate Tectonics.- 6.3.1 Subduction-Related Settings.- 6.3.2 Collision-Related Settings.- 6.4 Transform Fault Tectonics.- References.- 7 Geotectonic and Metallogenic Analysis of Orogenic Belts.- 7.1 Introduction.- 7.2 The Pan-African Orogenic Belts of Africa.- 7.2.1 The Arabian-Nubian Shield.- 7.2.2 The Damara Orogen, Namibia.- 7.2.3 The Lufillian Fold Belt.- 7.3 Metallogenic Epochs and Geotectonic Environments of Hydrothermal Mineral Deposits of the Orogenic Belts in New Zealand.- 7.3.1 Geotectonic Settings of the Tuhuan Orogeny and Related Hydrothermal Mineralisation.- 7.3.2 Geotectonic Settings of the Rangitata Orogeny and Related Hydrothermal Mineralisation.- 7.3.3 Geotectonic Settings of the Kaikoura Orogeny and Related Hydrothermal Mineralisation.- References.- III Hydrothermal Processes and Activities — Related Mineral Deposits.- 8 Alkali Metasomatism and Related Mineral Deposits.- 8.1 Introduction.- 8.2 Alkali Metasomatism in Continental Igneous Systems.- 8.2.1 Role of Volatiles in Granitic Magmas.- 8.2.2 Textural Features.- 8.2.3 Sodic Metasomatism and Albitites.- 8.2.4 Potassic Metasomatism and Microclinites.- 8.3 Alkali Metasomatism in Anorogenic Ring-Type Complexes.- 8.3.1 Fenites.- 8.4 Mineralisation Related to Alkali Metasomatism.- 8.4.1 Mineralisation in Ring Complexes of the Ijolite-Carbonatite Association.- 8.4.2 Mineralisation in Ring Complexes of the Alkaline Granite Association.- 8.4.3 Mineralisation Related to Alkali Metasomatism of Pegmatites.- References.- 9 Greisen Systems.- 9.1 Introduction.- 9.2 Greisenisation Processes.- 9.3 Geochemistry.- 9.4 Greisen-Related Mineral Deposits.- 9.4.1 Sn and W Geochemistry in the Greisen Environment — Deposition of Cassisterite and Wolframite.- 9.4.2 Sn Deposits Associated with the Acid Phase of the Bushveld Igneous Complex, South Africa.- 9.4.3 Sn-W Mineralisation at Brandberg West, Damara Orogen, Namibia.- 9.4.4 Endo- and Exogreisen Sn Mineralisation at Mount Bischoff, Tasmania.- 9.4.5 The Hercynian Sn-W Deposits of Southwest England, Cornwall and Portugal.- References.- 10 Porphyry Systems and Skarns.- 10.1 Introduction.- 10.2 Tectonic Settings.- 10.3 Classification of Porphyry Systems.- 10.4 Hydrothermal Alteration and Mineralisation.- 10.4.1 Lowell-Guilbert Model.- 10.4.2 Diorite Model.- 10.4.3 Alteration-Mineralisation of Carbonate Wall Rocks (Skarns).- 10.5 Mineral Deposits of Porphyry Systems.- 10.5.1 Panguna and Ok Tedi Porphyry Cu-Au Deposits.- 10.5.2 Porphyry Cu-Mo Deposits in Chile.- 10.5.3 Porphyry Mo Deposits of the Colorado Mineral Belt.- 10.5.4 Porphyry Mo Mineralisation in the Oslo Graben, Norway.- 10.5.5 Skarn Deposits in the Western USA.- 10.5.6 Other Types of Skarn Deposits.- 10.5.7 Porphyry Sn Deposits in Bolivia.- References.- 11 Fossil and Active Geothermal Systems — Epithermal Base and Precious Metal Mineralisation (Including Kuroko-Type Deposits).- 11.1 Introduction.- 11.2 General Characteristics of Epithermal Systems.- 11.2.1 Main Types of Epithermal Deposits.- 11.3 Volcanic-Hosted Epithermal Deposit Types.- 11.3.1 Epithermal Systems of Submerged Volcanic Structures.- 11.3.2 Hydrothermal Alteration.- 11.3.3 Mineral and Metal Zoning.- 11.4 Transport and Deposition of Precious Metals in Epithermal Systems.- 11.4.1 Boiling Depths and Metal Zoning.- 11.5 Active Geothermal Fields.- 11.5.1 Geothermal Systems of the Taupo Volcanic Zone, New Zealand.- 11.5.2 Salton Sea, California, USA.- 11.6 Volcanic-Hosted Epithermal Mineral Deposits.- 11.6.1 Hauraki Goldfields, Coromandel Peninsula, New Zealand.- 11.6.2 Epithermal Au in Lihir Island, Papua New Guinea.- 11.7 Sediment-Hosted Epithermal Deposits.- 11.7.1 Mineral Belts and Deposit Types of Nevada, USA.- 11.7.2 Nature of Fluids and Ore Genesis.- 11.8 Kuroko-Type Mineral Deposits.- 11.8.1 Kuroko Deposits.- 11.8.2 Precambrian Volcanogenic Massive Sulphide Deposits.- References.- 12 Hydrothermal Processes in Oceanic Crust and Related Mineral Deposits.- 12.1 Introduction.- 12.2 Physiography of the Ocean Floor.- 12.2.1 Mid-Ocean Ridges.- 12.2.2 Transform Faults and Fracture Zones.- 12.2.3 Seamounts and Volcanic Chains.- 12.3 Birth, Life and Death of an Ocean Basin.- 12.4 Oceanic Lithosphere and Ophiolites.- 12.5 Heat Flow, Oceanic Crust Metamorphism and the Nature of Related Hydrothermal Solutions.- 12.5.1 Heat Flow and Oceanic Crust Metamorphism.- 12.5.2 Nature and Composition of the Hydrothermal Solutions.- 12.6 Tectonic Settings, Sub-Sea-Floor Hydrothermal Processes, Hot Springs and Their Mineral Deposits.- 12.6.1 Tectonic Settings.- 12.6.2 Hydrothermal Processes and Types of Sulphide Deposits.- 12.6.3 Sub-Sea-Floor Hydrothermal Mineral Deposits.- 12.7 Oceanic Crust-Related Hydrothermal Mineral Deposits.- 12.7.1 Massive Sulphide Deposits of the Samail Ophiolite, Oman.- 12.7.2 The Cu Deposits of Cyprus Island.- 12.7.3 The Cu Deposits of the Matchless Amphibolite Belt, Namibia.- References.- 13 Hydrothermal Mineral Deposits of Continental Rift Environments.- 13.1 Introduction.- 13.2 Continental Rifting.- 13.2.1 Geophysical Signatures of Continental Rifts.- 13.3 Magmatism and Metamorphism Associated with Rifting.- 13.3.1 The Nature of Igneous Activity in Rift Systems.- 13.3.2 Metamorphism in Continental Rifts.- 13.4 Basin Formation and Volcano-Sedimentary Sequences in Continental Rifts.- 13.4.1 The Stratigraphic Record of Proterozoic Basins in South Africa.- 13.4.2 The Stratigraphic Record of Aulacogens.- 13.4.3 The East African Rift System.- 13.4.4 The Rio Grande Rift (USA).- 13.5 Continental Rifting in Space and Time — Hydrothermal Mineral Deposits.- 13.5.1 Early Stages of Continental Rifting.- 13.5.2 Aulacogens and Troughs — Intermediate Stages of Continental Rifting.- 13.5.3 Advanced Stages of Rifting.- 13.6 Hydrothermal Mineral Deposits in Incipient Rifts.- 13.6.1 The Messina Cu Deposits, South Africa.- 13.6.2 Olympic Dam (Roxby Downs), South Australia.- 13.6.3 Hydrothermal Activity in the Tanganyika Trough, East African Rift System.- 13.7 Hydrothermal Mineral Deposits in Aulacogens and Troughs at Intermediate Stages of Rifting.- 13.7.1 McArthur River and Mt. Isa, Northern Australia.- 13.7.2 The Sediment-Hosted Exhalative Massive Sulphide Deposits in the Namaqualand Metamorphic Complex, South Africa.- 13.7.3 Stratabound Cu-Ag Deposits of the Irumide Belt in Southern Africa.- 13.7.4 The Zambian Copperbelt.- 13.7.5 Stratiform and Stratabound Cu Deposits of the Keweenawan Rift.- 13.8 Mineral Deposits Related to Advanced Stages of Rifting — the Red Sea Deeps.- 13.9 Banded Iron Formation (BIF) of Proterozoic Age.- 13.9.1 The Mineral Deposits of the Transvaal-Griqualand Basins.- References.- 14 Stratabound Carbonate-Hosted Base Metal Deposits.- 14.1 Introduction.- 14.2 Mississipi Valley-Type Deposits (MVT).- 14.2.1 The Viburnum Trend, USA.- 14.2.2 Pine Point, Canada.- 14.3 Alpine-Type Deposits.- 14.4 Irish-Type Deposits.- 14.4.1 Mineral Deposits.- 14.5 Models of Ore Genesis for the MVT, Alpine and Irish Types.- 14.5.1 Karsting.- 14.5.2 Nature and Temperature of Fluids, Source of Metals and Sulphur.- 14.6 The Carbonate-Hosted Pb-Zn-Cu-Ag and V Deposits of the Otavi Mountain Land, Namibia.- 14.6.1 Geology, Structure and Metamorphism.- 14.6.2 Mineralisation.- 14.6.3 Tsumeb.- 14.6.4 Kombat.- 14.6.5 Berg Aukas.- 14.6.6 Models of Ore Genesis.- References.- 15 Crustal Hydrothermal Fluids and Mesothermal Mineral Deposits.- 15.1 Introduction.- 15.2 Metamorphism and Fluid Generation.- 15.2.1 Metamorphic Devolitilisation Reactions.- 15.2.2 Fluid Transport and Migration.- 15.2.3 Shear Zones.- 15.2.4 Metamorphic Vein Systems and Vein Growth.- 15.2.5 Mass Transport and Movement of Metals.- 15.2.6 Au in Hydrothermal Fluids.- 15.2.7 Oxygen and Hydrogen Isotope Systematics.- 15.3 Tectonic Settings.- 15.4 Archean Mesothermal Deposits.- 15.4.1 The Archean Greenstone Belts.- 15.4.2 Metallogenesis.- 15.4.3 Theories on the Genesis of Archean Mesothermal Au Deposits.- 15.4.4 Mesothermal Au Deposits of the Barberton and Murchison Greenstone Belts, South Africa.- 15.4.5 The Golden Mile, Yilgarn Block, Western Australia.- 15.4.6 The Hemlo Au-Mo Deposit, Superior Province, Canada.- 15.5 Mesothermal Vein Deposits of Phanerozoic Age (Turbidite-Hosted Au).- 15.5.1 The Ballarat Slate Belt, Victoria, Australia.- 15.5.2 Hydrothermal Lode Systems of Otago-Marlborough and the Southern Alps, New Zealand.- 15.5.3 The Juneau Gold Belt, Southeast Alaska.- 15.6 Mineral Deposits Formed by Multistage Ore Genesis.- 15.6.1 Unconformity-Related U Deposits.- 15.6.2 Au Mineralisation in the Central Zone of the Damara Orogen, Namibia.- 15.6.3 The Possible Role of Metamorphic Fluids in the Origin of the Witwatersrand Goldfields, South Africa.- References.- Epilogue.