Exploring for Minerals Using Geophysics: A Mineral System-Based Approach
The purpose of this course is to familiarise mineral exploration geoscientists with the very latest developments in our understanding of the geophysical responses of mineral systems. The course revises the mineral system concept and considers these ideas in a geophysical context. New targets, in additional to traditional deposit-scale targets are proposed, e.g. fluid/metal source zones, fluid conduits and palaeo-reservoirs. The geophysical responses of key mineral system components are considered from first principles. Physical property contrasts expected to be associated with different components are described and new methods of analysing petrophysical data are demonstrated. The use in mineral exploration of deep penetrating ‘academic’ geophysical methods is also described. Methods covered include the magnetotelluric method, deep seismic reflection profiling and teleseismic and ambient noise passive seismic methods. Finally exploring for mineral systems using geophysical methods is demonstrated using examples from three important deposit styles: carbonate-hosted base metals, magmatic Ni-Cu deposits in mafic/ ultramafic rocks and hydrothermal (orogenic) gold.
On completion of the course participants will: • Understand the mineral system concept and its implications for geophysical exploration, especially when exploring for blind targets • Know how to recognise responses from components of mineral system in their geophysical datasets • Be aware of recent developments in the use of deep-penetrating geophysical methods for mineral exploration • Understand how to use analyse petrophysical data to predict geophysical responses of mineral system components • Be familiar with the geophysical characteristics of common mineral system components, including the components of selected magmatic, sedimentary-basin-hosted and hydrothermal mineral systems.
1. Introduction: mineral exploration in 2017 • a. current exploration practice/strategy, • b. declining discovery rates, rising discovery costs • c. implications of going ‘under cover’ • d. government exploration incentive schemes/public domain data 2. Mineral systems • a. Description of the concept and implications for mineral exploration • b. Mineral system classification schemes • c. The importance of geographically widespread data and deep penetrating geophysical methods • d. New targets suggested by the mineral systems concept: source, reservoirs, pathways and the importance of associated alteration 3. Petrophysics • a. A new conceptual framework for petrophysical data: bulk-grain- texture • b. Importance of proper sampling • c. Importance of analysing the data in a geochemical/petrological/ geological framework • d. Workflow for petrophysical data in a mineral systems context: analysis in context of lithology, stratigraphy, metamorphism/alteration, location 4. Large scale and deep penetrating geophysical methods • a. Key mineral systems targets (major faults, craton margins, mantle metasomatism, fluid reservoirs, major magma chambers) and their geophysical expression • b. Potential field data (responses from mineral system components) • c. Magnetotelluric data (responses from mineral system components) • d. Active source seismic methods - deep reflection, refraction data (responses from mineral system components) • e. Passive seismic methods - teleseismic, ambient noise methods (responses from mineral system components) 5. Geophysics of selected mineral systems • a. Sedimentary basin-hosted system: Carbonate-hosted base metals (Mississippi Valley-type, Irish style) • b. Magmatic system: Ni-Cu in mafic/ultramafic intrusions • c. Hydrothermal system: orogenic gold
The course is designed for: • Industry, government and student geoscientists who are using the mineral system concept to guide exploration and wish to understand how geophysical methods can be integrated in to their exploration strategy • Geoscientists with a basic understanding of geophysical data sets seeking to be innovative in their use of geophysical exploration methods
Participants should have a basic understanding of the geology of mineral deposits and mineral exploration practice.
McCuaig, T.C. and Hronsky, J.M.A., 2014. The Mineral System Concept: The Key to Exploration Targeting Society of Economic Geologists Special Publication 18, pp. 153–175
About the Instructor
Professor Mike Dentith is Professor of Geophysics at The University of Western Australia, located in Perth, Western Australia. He has more than 25 years experience in teaching, research and consulting in petroleum and mineral exploration geophysics. Professor Dentith is a senior and foundation researcher at the Centre for Exploration Targeting, a minerals industry-funded research centre developing new exploration methods for the mining sector, where he leads the geophysical research theme. Current research projects include geophysical signatures of mineral deposits, hard-rock petrophysics, magnetotelluric and seismic methods applied to mineral exploration and using geophysical methods for assessing regional-scale prospectivity. This research is funded by industry and government. Professor Dentith is co-author of the award winning textbook, Geophysics for the Mineral Exploration Geoscientist, and editor of two case study volumes on the geophysical signatures of Australian mineral deposits. He has run numerous professional courses for industry, government and professional societies in Australia, South American, Asia, Europe and Africa.