Halogens in Surface Exploration Geochemistry; Evaluation and Development of Methods for Detecting Buried Mineral Deposits (NTS 93A/12, 93F/03)
- Colin Dunn, Independent Consultant

Areas of Focused Studies A significant part of central British Columbia has yielded few mineral occurrences due to a blanket of younger glacial materials concealing the rocks of interest. Development of an effective geochemical tool to detect concealed deposits would provide significant assistance to mineral exploration within these areas.

Volatile elements, such as the halogens (F, Cl, Br, I), are potential 'pathfinder' elements for locating mineral deposits. Halogens have been little-used in Canadian mineral exploration, partly because of a lack of easily accessible analytical methodologies. Their relationship to mineral deposits was investigated in this study and cost-effective analytical methodologies were developed for detecting low concentrations. The halogen data was examined in context of known deposits and conventional multi-element geochemical signatures.

Investigations involved the geochemical response in vegetation and soils at three Cu-Au and Au-Ag deposits in central British Columbia - Mount Polley, QR, and 3Ts.

Selected principal outcomes of the project:

  • The levels of labile halogens that can be expected in soils and vegetation from central BC have been defined;

  • Optimum cost-effective digestion and analytical procedures for determining labile components of halogens in soils and vegetation have been established.

  • Halogen signatures vary according to the nature of the mineralization. This indicates that each style of mineralization is likely to generate a different suite of positive halogen responses that have yet to be clearly defined; hence analysis for all four halogens is advisable.

  • Pine bark is the vegetation medium that best concentrates iodine, and gives good contrast for the other halogens.

Posters and Presentations
2006 : Halogens and Multi-Element Signatures in Soils and Vegetation: Investigating their use to explore for concealed mineral deposits
- Mineral Exploration Roundup Poster (pdf, 2.44MB)

Technical Articles
2006 : "Halogens in Surface Exploration Geochemistry: Evaluation and Development of Methods for Detecting Buried Mineral Deposits (NTS 093F/03), Central British Columbia"
- Geological Fieldwork 2005, Paper 2006-1 p.259-280 (pdf, 3.21MB)

Final Deliverables
Geoscience BC Report 2007-10
Halogens in Surface Exploration Geochemistry: Evaluation and Development of Methods for Detecting Buried Mineral Deposits

Much of the bedrock in central British Columbia has a cover of Quaternary deposits and/or volcanic rocks. Given the fact that the area is underlain by the generally 'fertile' Quesnellia Terrane, there is good reason to be optimistic that significant buried mineralization may be present. The challenge is, therefore, to develop a method for detecting mineralization hidden beneath this cover. Geoscience BC Report 2007-10 is aimed at enhancing the discovery of concealed mineral deposits using the halogen elements, focusing on soil and common vegetation from three target areas: Mount Polley (Imperial Metals Corp); QR (Cross Lake Minerals Ltd.); and 3Ts (Silver Quest Resources Ltd.).

The halogen elements (Fluorine, Chlorine, Bromine, Iodine) are commonly associated with the emplacement of mineral deposits. They are contained within the structure of many minerals and in saline fluid inclusions that are typical of a wide range of mineral deposits. Their volatility renders them good candidates to examine as 'pathfinder elements' in surface geochemical media, where they may be captured on soil particles and taken up by vegetation. Other studies have demonstrated the exceptional migrational abilities of Iodine and Bromine in different geological settings, and found these elements to be highly effective in exploring for orebodies at depths of up to 1000 m.

Geoscience BC Report 2007-10 reports on the optimal procedures for determining halogen concentrations in soil and vegetation, and examines new halogen data from the Mount Polley, QR and 3Ts deposits.

This project complements the parallel Geoscience BC project "A Comparative Assessment of Soil Geochemical Methods for Detecting Buried Mineral Deposits: 3T's Epithermal Au-Ag Prospect, Central British Columbia, Canada" by Stephen Cook and Colin Dunn, which was released in July as Geoscience BC Report 2007-7. Much of the new data in this report falls within Geoscience BC's QUEST Project area.


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