Geological interpretation of geophysical data for mineral exploration

 

Instructor

  Prof. Michael Dentith (The University of Western Australia)

Duration

  2 to 5 days

Disciplines

  Geophysics – Mineral Exploration

Level

  Intermediate

Language

  English

EurGeol

  10 to 25 CPD points

Keywords

 
 ELECTROMAGNETISM   GRAVITY   MAGNETICS   MINERALS   RESISTIVITY   RADIOMETRICS   INDUCED  POLARISATION 

 

Course description

The purpose of this course is to provide training in how to use geophysical methods in mineral exploration. Designed for industry, government and student geologists seeking to understand how to use geophysical datasets to explore and map, and geophysicists seeking to include more geology in to their interpretations, this course teaches participants to integrate geological and geophysical data in a mineral exploration context.

Core topics include the basic principles of the main geophysical exploration methods used in mineral exploration including the importance of optimal processing and display of these data and the strengths and limitations of the various methods. Particular attention is paid to extracting the maximum amount of geological information from the data, recognising noise-related artifacts in interpretation products and how to deal with the ambiguity when interpreting geophysical datasets.

The course is based around a series of practical exploration exercises involving real exploration data. These data are processed and displayed, associated petrophysical data are analysed and then both quantitative (image analysis) and quantitative (modelling) interpretation methods are used to create an interpretation that combines all available geological and geophysical data.

 

Course objectives

On completion of the course participants will:

• Understand how to integrate geological and geophysical information during mineral exploration
• Have experience in interpreting a range of real geophysical datasets in a mineral exploration context
• Have the ability to solve exploration challenges using geophysical methods
• Be familiar with state-of-the-methods for analysing petrophysical data
• Understand the capabilities and limitations of the various geophysical data types
• Be aware of the importance of geophysics in the future of mineral exploration

 

Course outline

The course comprises modules, the inclusion of which depends on its duration.

1. Introduction to geophysics

  • a. Geophysical methods used in mineral exploration
  • b. Geophysical anomalies and their sources
  • c. Ambiguity
  • d. Geophysical exploration practice
  • e. Cost of geophysics

2. Practical exercise 1 – geophysical anomalies and exploration strategy

3. Acquisition to display

  • a. Signal and noise
  • b. Sampling and survey design
  • c. Data display

4. Practical exercise 2a - Data display

5. Data enhancement

  • a. Wavelength-based enhancement
  • b. Gradient-based enhancements
  • c. Amplitude-based enhancements

6. Practical exercise 2b – data enhancement

7. Gravity and magnetic methods

  • a. Basic principles of gravity and magnetism
  • b. Reduction of gravity data – the influence of terrain
  • c. Reduction of magnetic data – the importance of levelling
  • d. Enhancing gravity and magnetic data (derivative-based enhancements, continuation, reduction to the pole, pseudogravity)

8. Practical exercise 3a – enhancing gravity and magnetic data

9. Petrophysics

  • a. Best practice in data collection and analysis
  • b. Rock and mineral density and magnetism
  • c. Physical properties and common geological processes

10. Practical exercise 3b – analysis of petrophysical data

11. Qualitative interpretation

  • a. Beyond ‘geological pattern recognition’ in image interpretation
  • b. Geophysical expressions of common geological features
  • c. Common pitfalls

12. Practical exercise 3c – interpretation of gravity and magnetic maps for exploration targeting

13. Quantitative interpretation

  • a. Representing the sub-surface with a geophysical model
  • b. Regional-residual separation
  • c. Forward modelling
  • d. Inverse modelling
  • e. Analysing a modelling result

14. Practical exercise 3d – modelling magnetic anomalies for exploration targeting

15. Radiometric data

  • a. Basic principles of radioactivity
  • b. Measuring natural gamma radiation
  • c. Processing and displaying radiometric data
  • d. Geology and geological processes and their effects on gamma radiation

16. Practical exercise 4 – interpreting radiometric data for exploration targeting

17. Electrical and electromagnetic methods

  • a. Basic principles of electricity
  • b. Electrical properties of rocks
  • c. Resistivity method
  • d. Induced polarisation method
  • e. Basic principles of electromagnetism
  • f. Electromagnetic data acquisition and interpretation

18. Practical exercise 5 – interpreting electrical and electromagnetic data for exploration targeting

19. Seismic reflection method

  • a. Seismic waves
  • b. Geological causes of variation in seismic properties
  • c. Processing and interpretation of seismic data

 

Participants' profile

The course is designed for:

• Industry, government and student geologists seeking to understand how to use geophysical datasets to explore for minerals
• Geophysicists seeking to improve the integration of geology in to their interpretations

 

Prerequisites

Participants should have a basic understanding of the geology of mineral deposits and mineral exploration practice. They should also be familiar with MS Excel.

 

Recommended reading

Dentith, M. and Mudge, S.T., 2014. Geophysics for the Mineral Exploration Geoscientist. Cambridge University Press.

 

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.

 

 

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