The Targeted Geoscience Initiative 4 (TGI-4): Intrusion-Related Ore Systems

The scientific research and results for this project are available via GEOSCAN

Intrusion-related ore systems are formed when molten rock (magma) intrudes into the Earth’s crust, but solidifies before it can reach the surface. As this magma cools very slowly, there is enough time for large mineral crystals to grow; giving many intrusive rocks a coarse-grained, granite-like texture. Some of these rocks may grow crystals significantly larger than the rest and with one or more minerals; these are called ‘porphyry’ rocks. As porphyry rocks cool and crystallize they can produce large volumes of hot, salt-rich fluids that carry high concentrations of base metals such as copper (Cu), molybdenum (Mo), tungsten (W) and tin (Sn).

Porphyry and intrusion-related mineral deposits are important to Canada’s economy, as they account for more than 40% of our copper and approximately 25% of our gold (Au). Globally, they contain more than 50% of the world’s copper and 95% of its molybdenum. Porphyry deposits typically contain only low to medium concentrations of economically important metals, but these can occur within extremely large volumes of rock. The largest single source of copper in Canada is the porphyry-related Highland Valley Copper mine in British Columbia, and the largest copper deposits known worldwide are almost all porphyry-related1.

Exploration for porphyry mineral deposits has suffered a declining success rate in recent years, because most of the more easily-found deposits are already in production. As the world moves forward into the 21st century it is clear that increasing reliance will have to be placed on new discoveries of deposits that are buried under thick sediment or overlying rock. In order to be able to do this, new and more effective exploration criteria are required to identify and evaluate porphyry and intrusion-related mineralizing systems at depth.

The Intrusion-Related Ore Systems Project will focus on two important questions:

  1. are there distinctive characteristics that indicate the location of a deeply-buried mineral deposits; and,
  2. are there traces of development and growth of the preserved mineral deposits and, if so, what role did different factors have and which are important for creating the largest and most valuable porphyry-related deposits?

Studies into Canadian Cu-Mo-Au and W-Mo-Sn deposits will provide many of the geological and geochemical clues that will allow us to locate and assess deeply-buried mineral deposits.

Project activities will be centred on known metal concentrations – such as the south-central district of British Columbia, and the Canadian Appalachians – as a means of developing greater understanding of the processes that formed these valuable deposits and testing new exploration techniques. Field-based studies will integrate bedrock and surface information to improve the interpretation of existing geochemical and geophysical data, and will lead to novel exploration methods specifically developed for successful discovery of buried intrusion-related deposits. A large part of this research will include training and mentoring of students; the next generation of explorers for intrusion-related mineral deposits.

For more information about on the Intrusion-Related Ore System projects, contact:

Mike Villeneuve, Program Manager
Geological Survey of Canada
Natural Resources Canada
601 Booth Street
Ottawa ON K1A 0E8
Tel.: 613-995-4018
E-mail: TGI-IGC@NRCan-RNCan.gc.ca

1 Natural Resources Canada