AGI Soil Gas Surveys

The Survey

AGI surveys identify, measure, and map volatile and semi-volatile organic compounds in soil gas, water, air, and sediment. They have been used extensively for oil and gas exploration, with remarkable success, and have recently been used for the detection of carbon and sulphur compounds associated with certain types of gold and base metals mineralization.

The Technology

AGI survey module was originally developed in 1992 by Dr. Ronald Klusman, of the Colorado School of Mines and the USGS.

The module is made of expanded polytetrafluoroethene (ePTFE) adsorbent modules enclosed in a GORE-TEX membrane. The GORE-TEX membrane is engineered to screen the size of molecules passing through to the adsorbent modules. The ePTFE is a material capable of adsorbing mobile soil gases and vapour transported metals migrating to surface.

The ePTFE ultra-sensitive adsorbent material, coupled with the time-integrated nature of the survey and the thermal desorption analysis put AGI surveys a leap ahead of any other soil gas survey in the search for deeply buried mineral deposits.

Analysis

The AGI laboratory is DoD ELAP and ISO 17025 accredited, ensuring the highest quality control available in the industry.

Samples are analyzed for:

88 compounds incl. C3-C20

–        Aliphatics

–        Aromatics

–        Oxygenated compounds

Inorganic and sulfur compounds

–        Hydrogen sulphide (H2S)

–        Molecular sulfur (S8)

–        Dimethylsulfide (CH3)2S

 –        Carbon disulfide CS2

–        Carbonal sulfide CO

–        Sulphur dioxide SO2

–        Mercury

 The Basic Sampling Methodology

  1.          Use hand tools to make a small pilot hole (1 cm          diameter) to a depth of 50 to 60 cm

2.          Remove AGI sampler from container and record serial number and corresponding site number and GPS position

3.          Insert  AGI sampler into the pilot hole using insertion rod

4.          Leave in the ground for 30-60 days

5.          Return to location and remove AGI sampler using the highly durable collector

6.         Ship samples to AGI laboratory for analysis

The AGI sampler adsorbs part-per-billion (ppb) concentration levels of various organic and inorganic constituents. Those compounds are thermally desorbed and analysed and quantified by mass spectrometry.

Once the samples have been analyzed, geochemical modeling of the results is achieved by identifying anomalies in the soil gas signatures using statistical clustering, factor analysis and other statistical techniques.

Case Studies

Borealis Gold Deposits – Nevada, USA

  • Volcanic rock-hosted, high sulphidation, epithermal gold system
  • Soil gas anomalies corresponded well to known mineralization and alteration.

Cerro De Maimon – Dominican Republic

  • VMS deposit in tropical environment
  • Anomalous geochemical signature over sulfide pit zone and underground sulfide zone

Lonestar Copper Deposit – Arizona, USA

  • Target mineralization buried by 250 – 550 meters of tertiary volcanic cover
  • Clearly detected and differentiated the non-mineralized area from the buried copper mineralization

 

CO Geosciences Represent Amplified Geochemical Imaging LLP (AGI) in Canada.

We work closely with AGI on all aspects of survey planning, implementation, analysis and interpretation.