Technical Overview

Traditional geochemical exploration techniques rely on the use of acid, cyanide or flux leaching dissolution of primary and secondary dispersion samples to extract the relevant metal component to delineate anomalies. The extraction is followed by appropriate instrumental analysis and interpretation.

Application of these techniques is appropriate where mineralisation has a moderate to strong surficial geochemical expression. An increasing number of current mineral discoveries are commonly too deeply buried, or have too weak a surficial geochemical signature to be detected by traditional geochemical techniques. As a result, vast tracts of potentially the most fertile geological terrains of Australia, and indeed, other continents, are sterilised to geochemical exploration through lack of an appropriate sampling and analytical protocol. Such areas, generally of Precambrian age, host the greater percentage of world-class ore bodies.

The geochemical exploration protocols which have been developed by our partners specifically address the issue of deeply buried, or blind, mineral resources lacking a traditional surface geochemical response. The techniques have been developed and been extensively evaluated and have resulted in the successful delineation of blind mineralisation, and diamond host rocks, to depths respectively in excess of 100 and 50 meters in various geomorphological settings. These are associated with both residual and transported overburden, including aeolian dune deposits and, in the case of kimberlite pipes, sandstone.

A number of protocols, based on either solution or laser ablation Inductively coupled plasma-mass spectrometric analytical techniques are utilized in analysis of bacterial soil leachates;

Our primary interest relate to the identification of precious and base metal anomalies, our investigation program is highly structured, our methodology in the first instance involves bacterial soil leachate protocols. This is because analytical techniques, based on enzyme and differential leaching technology, have been used with varying success and in many cases has been useful in the delineation of geochemical anomalies associated with precious and base metal mineralisation. However, their use is largely limited to deposits that are relatively close to surface beneath residual overburden. Whereas our methodology is based on the use of specific genetically engineered bacteria to selectively enhance geochemical anomalies in both deep residual and transported overburden to depths in excess of 100 meters.

Our technique has been successfully used over blind mineral deposits. Achieving excellent multi element anomaly definition, involving up to 60 elements, where as other available techniques have failed to register geochemical anomalies.

The underlying premise of the technique is that hydromorphic dispersion of ore-related elements will occur wherever an oxidising ore body interacts with ground water. Capillary migration of ground water, with entrained ore elements, to the surficial environment is naturally necessary for detection by most geochemical techniques. However, the deeper the ore body, the more subtle the surficial geochemical dispersion halo, with the result that the concentrations of ore-related elements introduced into surficial soils rendering their detection by traditional methods virtually impossible.

Our technology relies on the detection of in-situ, and vastly concentrated, labile metal ions and ion complexes in surficial soils. A genetically engineered bacterium is used to “leach” this labile metal component of the soil and concentrate it within the organism itself. Such bacteria may fix up to 10% metal within their bodies and so represent extreme concentrators of hydromorphically dispersed metal. Offsetting the markedly enhanced concentration of metal by the bacteria, is the fact that the mass of the bacteria, as a component of the total sample, is minuscule. Hence, our protocol selectively extracts the metal-rich bacteria, and routinely measures concentrations of metals in the derived leachates. The leachates are analysed using a customised and optimised inductively coupled plasma-mass spectrometer capable of routinely detecting elements, across the mass spectrum, at the low levels required.

In some cases, where the soil is of a very open texture, or where considerable barriers of sub cropping clay exist, significant hydromorphic anomalies may not occur in the surficial materials.

To further illustrate the potential of our methodology, consider for a moment kimiberlites and lamproites which are the principal host rocks for primary diamond accumulation at high levels within the Earth’s crust. Only a small proportion of kimberlites and lamproites are diamond-bearing and a still smaller number are economic. Kimberlites and lamproites are typically ultramafic in character, commonly form as pipes and are readily weathered leading to their rapid elimination from surface exposures. Not uncommonly, the weathered “pipe depressions” become infilled with clastic mineral detritus which, depending upon age, may be lithified. The country rock adjacent to kimberlites and lamproites may be sedimentary, igneous or metamorphic in origin, irrespective of composition is usually sharply chemically contrasted to the superimposed kimberlite and/or Iamproite intrusions. It is this chemical perturbation that facilitates geochemical delineation of buried or blind kimberlites and/or lamproites.

The bacterial leach/analytical protocol used to delineate blind or buried kimberlite and/or lamproite intrusions is essentially the same as for precious and base metals. Because some 62 elements and their isotopes are routinely analysed, the protocol has the capacity to detect the chemical perturbation caused by the kimberlite and/or lamproite intrusive. Hydromorphic dispersion to the surficial environment, of elements derived by ground water interaction with kimberlite and/or lamproite, is detected and enhanced using specific element ratio products. Successful delineation of diamondiferous kimberlites beneath 50 meters of sandstone and capping of unconsolidated debris, has been achieved. This has occurred in areas where drill targeting, based on magnetics, has not been possible due to the overall magnetic character of the soils within the search area.