Ore Deposit Geology

Ore Deposit Geology

JOHN RIDLEY

Colorado State University

Ore deposit geology may be taught late in a student’s undergraduate programme, or even at the beginning of a graduate programme. At this stage the student is able to link many of the concepts involved in ore genesis into his or her knowledge of the building blocks of the geosciences. Or it may be taught early, to show students potential applications of their emerging knowledge. This book is designed for the former case and also to be a reference if a student chooses to work professionally in the field. Knowledge typical of standard undergraduate courses in mineralogy, igneous, metamorphic and sedimentary geology, structural geology and tectonics, and geomorphology are assumed, together with some basic chemistry. It is not assumed that students have had courses in isotope geochemistry

or in geochemical thermodynamics.

The subject is scientifically expansive. There are few areas of the Earth sciences which are not touched upon in a thorough study of the subject. A balance needs however to be reached in teaching between detail and breadth. Some geologists work on one deposit type all their lives; others need to have enough knowledge of all types to make suitable judgements when they are called to evaluate them. A balance also needs to be reached between the local and the global. A practising ore deposit geologist may remain in one area or work over the world. The subject thus needs to be taught with case studies from globally, but also tailored to local geology.

It was a truism while I wrote this book, over the years before, and hopefully for at least a few years after, that the professional community of ore deposit geologists needs to become scientifically more sophisticated to be successful in our search for resources to replace those that are being mined. The easy to find, outcropping ores are almost all found. We need to be able to predict the likely positions of ores, and find them and evaluated them with a reasonable success rate through drilling to depths of a few hundred metres. Accurate prediction will require good knowledge of the nature of ore, of empirical markers of ore systems, and accurate conceptual models of how ores form. It is with the aim of training with all the ends and needs listed above this book was written. Description, genetic analysis and discussions of advances in understanding of other sub-disciplines of the geosciences are combined. About 30 deposit types are described and discussed in varying depths.

I made two specific choices in format that warrant some explanation: First, for the benefit of simplicity, I felt the need to take stands on some of the conflicting interpret- ations and debates in the community of ore deposit geologists and to write some of the deposit descriptions and analyses from the viewpoint of one ‘side’. Debate is an integral part of science. Descriptions run the risk of being supplanted as new discoveries are made. Genetic analysis runs an even greater risk. We need to keep aware that at least some of our interpretations, especially of the unknowable of ore genesis in the geological past, are at all times ‘castles in the air’. We need further to be aware that our interpretations can be intensely personal.

DESCARGAR ORE DEPOSIT GEOLOGY