A key factor in the golden age of mineral discoveries in the 1960’s and 1970’s was the application of regional scale geochemical surveys. At that time, it was possible to analyze only a handful of elements (Au, Cu, Pb, Zn, As) at commercial assay laboratories. The assay techniques available at the time were not that sensitive for the purpose for which they were being used, and it is only the really obvious mineral systems that would have been detected. Nevertheless, this was a hugely successful period of exploration.
There have been huge advances in analytical techniques since then, and it is now possible to analyze half of the periodic table to detection limits well below average crustal abundance levels. Unit assay costs in real dollar terms are now far cheaper than they have ever been. Now that we have commercial assay techniques that are ideally suited to these regional reconnaissance geochemical programs, this is an activity that is undertaken by remarkably few explorers!
The big advantage of the ICP analytical suites is that the additional elements can be used to characterize the sample media. As well as mapping the pathfinder anomalies, the other elements can be used to map bedrock lithologies and to give information about regolith processes. Metals like Au, Cu, Zn and Pb that form chloride complexes are very mobile and readily depleted in lateritic weathering profiles. There are still great opportunities for new discoveries in places with leached regolith profiles like Western Australia, by using the full suite of pathfinder elements, and using the major elements to characterize the sample media. Mineral Mapping is experienced and well qualified to advise clients on the planning and interpretation of regional geochemical surveys.