Platinum Group Element And Magmatic Sulfide Deposits

This book is written by a leading authority on the subject of magmatic sulfide deposits. An overview of deposit types, accompanied by a summary of the resources of nickel, copper and platinum-group elements in the world’s principal known deposits, is followed by a summary of the relevant physical chemistry. The core of the book comprises a discussion about the geology and geochemistry of each of the deposit types in turn, accompanied by the implications of this data to the origin of the deposits in the light of our understanding of the chemical processes involved. A final chapter focuses on the use of the genetic concepts in exploration.

Processes and Ore Deposits of Ultramafic-Mafic Magmas through Space and Time focuses on the fundamental processes that control the formation of ore deposits from ultramafic-mafic magmas, covering chromite, platinum-group element (PGE), Ni-sulfides and Ti-V-bearing magnetite. The exploration, exploitation and use of these magmatic ores are important aspects of geology and directly linked to the global economy. Magmatic ores form from ultramafic-mafic magmas and crystallize at high-temperature after emplacement into crustal magma chambers, and are genetically linked to the evolution of the parental magmas through space and time. This book features recent developments in the field of magmatic ore deposits, and is an essential resource for both industry professionals and those in academia. Elucidates the relationships between tectonic settings and magmatic ore mineralization Provides the links between magma generation in the mantle and ore mineralization at crustal levels Features the latest research on changing patterns in magmatic ore mineralization through time and their bearing on the chemical evolution of the Earth’s mantle

The platinum-group elements (PGE) include platinum, palladium, rhodium, ruthenium, iridium and osmium. They are currently receiving world-wide attention as an attractive exploration target because they offer the dual attraction of rare, high value precious metals as well as major industrial applications. Platinum has aesthetic qualities, combined with a permanent lustre, which encourage its use in the manufacture of jewellery and, like gold, it also finds an investment role. Platinum, rhodium and palladium have important applications as catalysts, enabling petroleum and other fuels and chemicals to be produced efficiently from crude oil. This book gives a practical set of guidelines for implementing a programme of PGE exploration, detecting subtle indications of mineralization and assessing the economic potential of a group of mafic or ultramafic rocks. Background material is given on the economic and geological framework of the PGE in the first chapter, while theoretical aspects of magma chemistry are covered in the next three. Chapters 5 and 6 review current world-wide exploration activity within the context of available reserves of PGE, and in Chapter 7 factors which need to be considered in exploration for new deposits are outlined. The last chapter discusses evaluation guidelines. As the PGE are both costly and almost indestructible they are normally recycled; nevertheless, a substantial annual input of new metal is needed to replace process losses, to permit increases in capacity in the dependent industries and to provide for new uses. For example, a major new market for platinum will be created if the European Community countries are required to fit catalytic converters to new cars. At present, South Africa and the USSR are the sources of most of the western world's newly mined PGE, with virtually all the South African production derived from the Bushveld Complex. Much of the material presented in this book is based on the author's experience of these rocks, and emphasis is given to the dominant role played by magmatic sulphides as potent collectors of PGE. Consumers of minerals and metals, however, prefer to have a diversity of supply and a new PGE producer is therefore likely to attract a ready market. Not only does the book provide a wealth of practical information for mining geologists, it also contains much of interest to those in natural resource management and investment.

Acknowledgements xix pioneering workers on igneous layering in Greenland xx Wbrkshop participants xxii Henning Sfl!rensen, University of Copenhagen, Dermark. Latte Melchior Larsen, Geological SUrvey of Greenland, Copenhagen, Dermark. Abstract 1 1 • Introduction 1 1. 1 The agpaitic rocks of the Ilimaussaq intrusion 3 2. Igneous layering in the Ilimaussaq intrusion 4 3. Mineralogy of the layered kakortokite series 15 4. Chemistry of the layered kakortokite series 19 5. Origin of the kakortokite layering 20 5. 1 Discussion 22 6. Conclusion 25 References 26 2. I. AYERn«;r CCMPl\CTIOO NID PCBJ. "--MN}tATIC ~ IN '!HE KLOKKEN INTRUSIOO 29 Ian Parsons and SUsanne M. Becker, University of Aberdeen, U. K. Abstract 29 1. Introduction 30 2. Age of the intrusion 31 3. General structure and mineral variation 31 vi TABLE OF CONTENTS 3. 1 Nomenclature of rock types 31 3. 2 Bulk chemical and modal variation 36 4. The contacts and wall-rocks 37 4. 1 Guter contact 37 4. 2 The gabbro sheath 37 4. 3 The unlaminated syenite sheath 39 4. 4 The gabbro-syenite transition 41 5. The layered series 43 5. 1 General relationships 43 5. 2 Granular syenites 43 5. 2. 1 Structure and cryptic variation 43 5. 2. 2 Origin of granular layers 46 5. 2. 3 Trace elements and chamber dlinensions 47 5. 3 Laminated syenites 48 5. 3. 1 General features 48 5. 3. 2 Mineral layering 51 5. 3.

Platinum-group elements (PGE) are important as petrogenetic tracers, but owing to their low abundances and complex behaviour they are among the least understood elements in geochemistry. This study investigates the mechanisms of PGE fractionation in ultramafic systems (komatiites, komatiitic basalts, ferro-picrites) and focuses on the role of chromite. Samples from a range of occurrences have been analysed to assess potential controls on PGE behaviour, such as geochemical affinities (Munro-type and Karasjok-type), age (2.0 and 2.7 Ga), emplacement styles, metamorphic grade and nickel-sulphide mineralisation endowment and style. -- Data obtained by in-situ laser ablation ICP-MS analysis provide the first direct evidence that Ru can exist in solid solution in chromite with concentrations up to several hundred ppb. The data show that the behaviour of Ru is dominantly controlled by the sulphide-saturation state. In systems that did not equilibrate with a sulphide liquid, chromites have distinctly higher Ru concentrations than chromites from systems that interacted with a sulphur-source during crystallisation. Carius tube digestion isotope dilution ICP-MS analyses of chromite separates confirm the accuracy of the in-situ study and also show that Ir is weakly compatible in chromite. Anomalously high Pt and Pd concentrations in chromite separates reflect the presence of platinum-group minerals (PGM) and suggest that PGM are common accessory phases in komatiites. A study of the PGE-mineralogy shows that PGM in komatiites can be of magmatic and post-magmatic origin and that they often remain undetected due to grain sizes less than 5 urn. As a consequence, the presence of PGE minerals has to be taken into account when whole-rock PGE signatures are interpreted. -- The association of Ru-poor chromites with Ni mineralisation and Ru-rich chromites with barren systems provides a new tool for the exploration for nickel-sulphide deposits. This model applies to all magma types and is independent of the age, the geochemical affinity, and other sample characteristics.

As the importance and dependence of specific mineral commodities increase, so does concern about their supply. The United States is currently 100 percent reliant on foreign sources for 20 mineral commodities and imports the majority of its supply of more than 50 mineral commodities. Mineral commodities that have important uses and face potential supply disruption are critical to American economic and national security. However, a mineral commodity's importance and the nature of its supply chain can change with time; a mineral commodity that may not have been considered critical 25 years ago may be critical today, and one considered critical today may not be so in the future. The U.S. Geological Survey has produced this volume to describe a select group of mineral commodities currently critical to our economy and security. For each mineral commodity covered, the authors provide a comprehensive look at (1) the commodity's use; (2) the geology and global distribution of the mineral deposit types that account for the present and possible future supply of the commodity; (3) the current status of production, reserves, and resources in the United States and globally; and (4) environmental considerations related to the commodity's production from different types of mineral deposits. The volume describes U.S. critical mineral resources in a global context, for no country can be self-sufficient for all its mineral commodity needs, and the United States will always rely on global mineral commodity supply chains. This volume provides the scientific understanding of critical mineral resources required for informed decisionmaking by those responsible for ensuring that the United States has a secure and sustainable supply of mineral commodities.