Cordilleran Geochemistry Project: Comparative Assessment of New Geochemical Methods for Detecting Buried Mineral Deposits in Central BC (NTS 93F/03)
- Stephen Cook & Colin Dunn

Project Study Site The study investiged the geochemical response, in soils and Quaternary materials, of a Au-Ag epithermal deposit (3T's deposit) in central BC. The study comprised an integrated field and laboratory investigation focusing on comparative analytical digestions and selective extraction studies from various soil profiles across the deposit.The project objective was to determine and recommend the most effective geochemical methods for property-scale evaluation of buried mineral targets in drift-covered terrain by evaluating and comparing commercially-available analytical methods and evaluating the most suitable soil media and horizons. Effective mineral exploration in this region has been hindered by thick forest cover, an extensive blanket of till and other glacial deposits and, locally, widespread basalt cover. Together these barriers to exploration have obscured the potential for discovery of new deposits. Regional geochemical surveys have been effective as reconnaissance exploration techniques, but few studies have been conducted into the use of surficial geochemistry to aid in prioritizing regional geochemical anomalies at property scale.

This project was complementary to the project: "Halogen Geochemistry: Development of New Geochemical Methodology, Using Soils and Vegetation, for Detecting Mineral Deposits Concealed by Volcanic Rocks and Overburden in Central British Columbia." (Dunn, Cook and Hall). Samples from a range of soil horizons were submitted for comparative analysis by several selective extraction analytical methods. This project was envisioned as a smaller Cordilleran analogue of the successful central Canadian CAMIRO Deep Penetrating Geochemistry project and its successors. No such publicly available comparative geochemical methodology studies have been conducted in the Cordillera.

Comparative extractions and analyses included:

  • aqua regia digestion/ICP-MS
  • Na-pyrophosphate extractions
  • Enzyme Leach
  • MMI Mobile Metal Ion
  • Soil Gas Hydrocarbons
  • Soil Desorption Pyrolysis
  • Soil pH
Results will assist companies in mounting effective geochemical exploration programs for blind targets, particularly those smaller exploration companies that do not have in-house geochemical staff.

Posters and Presentations
2006 : Preliminary Results of the Cordilleran Geochemistry Project - A Comparative Study of Soil Geochemical Methods for Detecting Buried Mineral Deposits - 3Ts Au-Ag Prospect, Central British Columbia
- Mineral Exploration Roundup Poster (pdf, 2.28MB)

Technical Articles
2006 : "Preliminary Results of the Cordilleran Geochemistry Project: A Comparative Assessment of Soil Geochemical Methods for Detecting Buried Mineral Deposits, 3Ts Au-Ag Prospect (NTS 093F/03), Central British Columbia"
- Geological Fieldwork 2005, Paper 2006-1 p.237-257 (pdf, 15.6MB)

Final Deliverables
Geoscience BC Report 2007-7
A Comparative Assessment of Soil Geochemical Methods for Detecting Buried Mineral Deposits: 3T's Epithermal Au-Ag Prospect, Central British Columbia, Canada


Geoscience BC Report 2007-7 describes the methods and results of a multimedia geochemical orientation survey conducted during June and July 2005 over the 3Ts epithermal Au-Ag prospect in the Interior Plateau region. Effective mineral exploration in the Nechako Plateau and adjoining regions of central British Columbia has been hindered for many years by thick forest cover, an extensive blanket of till and other glacial deposits and, locally, widespread Tertiary basalt cover. This project, funded by Geoscience BC, investigates the surficial geochemical response in soils and Quaternary materials of epithermal Au-Ag mineralization at 3Ts. This region is highly prospective for the discovery of epithermal Au deposits, among other mineral deposit types, and the low-sulphidation 3Ts prospect is one of the more significant examples in central BC of this type.

The objective of this project was to determine and recommend the most effective field and laboratory geochemical methods for property-scale evaluation of buried mineral targets in drift-covered terrain, by 1) evaluating the most suitable soil media and horizons for field sampling, and 2) evaluating and comparing commercially available analytical methods. No similar publicly available comparative geochemical methodology studies have been conducted in the western Cordillera. This project complements the parallel Geoscience BC research project by Colin Dunn on the effective use of halogen geochemistry of soils and vegetation for exploration.

 



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