A biogeochemical and follow-up study to investigate the effectiveness of MMI, Ionic Leach and deionised water extractions on Ah horizon samples at Kwanika (NTS 93N)
- Dave Heberlein, Heberlein Geoconsulting
Orientation surveys carried out at Kwanika and Mt. Milligan as part of Geoscience BC Project 2009-019 showed that deeply buried mineralization can be detected using soil geochemistry. At Kwanika in particular (GBC Report 2010-3), where soil profiles are in pristine condition (i.e. not disturbed by surficial activities), convincing responses to mineralization were obtained from the Ah horizon using conventional aqua regia and sodium pyrophosphate extractions. These methods detected copper-gold mineralization as deep as 300 metres below the surface. Other selective and partial extractions, including a number of laboratory specific methods such as MMI, Ionic Leach, Enzyme Leach and BioLeach, failed to convincingly detect the mineralization in B and C horizon samples. One of the limitations of the study was that not all extractions were performed on all soil horizons, therefore it is unknown whether these methods would define similar anomalies if used on Ah horizon samples.
This is a follow-up study to investigate the geochemical responses from MMI, Ionic Leach and Deionised water on Ah samples. It is also investigating the biogeochemical response in different tree species to determine whether the Ah horizon anomalism is due to accumulation of metals taken up by trees and shed as needles and leaves into the A horizon or whether the organic-rich soil horizon is acting as a trap for mobile metal ions derived from the mineralization at depth.
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