Accurately identifying what may lie deep beneath the surface is an ongoing mineral exploration challenge in British Columbia and beyond. This is particularly true in central BC, where a layer of variable thickness glacial sediments, known as ‘overburden’, covers potential mineral deposits.
Currently mineral explorers use geochemical techniques to analyze samples of overburden materials to help ‘zero in’ on the potential location of mineral deposits deep below the surface.
The field of genomics is developing rapidly, and genomic sequencing has the potential to provide effective new exploration tools by measuring microbial activity. Bacteria are very sensitive and responsive to chemical and physical changes in their environment. Subtle changes in metal availability can have a dramatic impact on microbial communities and their levels of activity.
This project fits under Geoscience BC’s Strategic Objective of ‘Advancing Science & Innovative Geoscience Technologies’ and the goal to:
- Partner on bioscience and genomic research projects that assist with understanding mineral and coal deposit formation, resource development and impacts.
Specifically, this proof-of-concept study collected samples over known mineral deposits in BC and determined:
The primary goal of this project was to test whether high-throughput DNA sequencing technologies can enable the use of soil microbial community profiling as a robust, efficient, and cost-effective tool to identify buried mineral deposits
This project is helping to develop a new exploration technique which could help identify a mineral deposit when used in conjunction with other geochemistry, geophysical and geological information.
In July 2015, the research team collected soil samples for this project from two sites in BCs South Central Region:
- Deerhorn copper-gold porphyry deposit operated by Consolidated Woodjam Copper; and
- Highland Valley Copper (HVC) Highmont South copper-molybdenite (Cu-Mo) porphyry operated by Teck Resources Ltd.
How was the data collected?
Soil-forming processes give rise to distinct horizons in a soil profile. For this project the Bh horizon, which is made of accumulated organic matter, was sampled. Care was taken to avoid contamination, so the samples were sieved through a quarter-inch screen on site and sealed in double plastic bags, then maintained in a refrigerated environment and frozen on return to the University of British Columbia (UBC). The soil samples were then ‘incubated’ in sealed plastic bags in dark cupboards at UBC.
The samples were then submitted for genomic testing. Since the human genome was sequenced in 2003, genomic sequencing technology has become significantly faster and cheaper as technology has improved. This includes the quick processing of terabytes of data. Today, high-throughput next-generation sequencing technologies mean researchers can profile the diversity and activity of thousands of microbe species in soils to identify reliable indicators needed to apply the technique to mineral exploration more widely.
What Was Found?
The research team compared the bacteria found in soils above mineral deposits with soil collected away from known mineralization (“background soil”). Groups of indicator bacteria species were found in the soils above mineralization (positive indicator species) and the background soils (negative indicator species).
For HVC, the researchers identified 24 indicator bacteria species: 9 positive indicator species and 15 negative indicator species.
At Deerhorn, the analysis provided 47 indicators with 32 positive indicator species and 15 negative indicator species.
The researchers produced maps of the distribution of positive indicator species that correlated with the known location of buried orebodies.
This research determined that the integration of microbial community information with soil chemistry and landscape development, coupled with geology and geophysics, has significant potential as a mineral exploration technique.
This project was co-led by Dr. Peter Winterburn and Geoscience BC would like to acknowledge Dr. Winterburn’s valuable and lasting legacy, which includes this project. We would also like to thank his colleagues for continuing the research after his passing.