Ann: Results of Annual General Meeting , page-84

Here is a text book explanation of EMs ...allows targeted exploration of magnetic (i.e. metallic) targets. More bang for your drilling buck. In this case, worth getting excited over given primary mineralisation has already been identified. But the drill never lies ... Chrs Pete


3. Airborne Electromagnetic Surveys
The general objective of AEM (Airborne ElectroMagnetic) surveys is to conduct a rapid and relatively low-cost search for metallic conductors, e.g. massive sulphides, located in bed-rock and often under a cover of overburden and/or fresh water. This method can be applied in most geological environments except where the country rock is highly conductive or where overburden is both thick and conductive. It is equally well suited and applied to general geologic mapping, as well as to a variety of engineering problems (e.g., fresh water exploration.)
Semi-arid areas, particularly with internal drainage, are usually poor AEM environments. Tidal coasts and estuaries should be avoided. Weathered maific flows can provide strongly conductive backgrounds, particularly flows of Tertiary or Quaternary age.

Conductivities of geological materials range over seven orders of magnitude, with the strongest EM responses coming from massive sulphides, followed in decreasing order of intensity by graphite, unconsolidated sediments (clay, tills, and gravel/sand), and igneous and metamorphic rocks. Consolidated sedimentary rocks can range in conductivity from the level of graphite (e.g. shales) down to less than the most resistive igneous materials (e.g. dolomites and limestones). Fresh water is highly resistive. However, when contaminated by decay material, such lake bottom sediments, swamps, etc., it may display conductivity roughly equivalent to clay and salt water to graphite and sulphides.

Typically, graphite, pyrite and or pyrrhotite are responsible for the observed bedrock AEM responses. The following examples suggest possible target types and we have indicate the grade of the AEM response that can be expected from these targets.
• Massive volcano-sedimentary stratabound sulphide ores of Cu, Pb, Zn, (and precious metals), usually with pyrite and/or pyrrhotite. Fair to good AEM targets accounting for the majority of AEM surveys.
• Carbonate-hosted Pb-Zn, often with marcasite, pyrite, or pyrrhotite, and sometimes associated with graphitic horizons. Fair to poor AEM targets.
• Massive pyrrhotite-pentlandite bodies containing Ni and sometimes Cu and precious metals associated with noritic or other mafic/ultramafic intrusive rocks. Fair to good AEM targets.
• Vein deposits of Ag, often with Sb, Cu, Co, Ni, and pyrite in volcanic and sedimentary rocks. Generally poor AEM targets.
• Quartz veins containing Au with pyrite, sometimes also with Sb, Ag, Bi, etc., in volcanic or sedimentary (and possibly intrusive) rocks. Poor AEM targets.
• Skarn deposits of Cu, Zn, Pb, and precious metals, usually with pyrite and magnetite, around igneous intrusions. Fair to poor AEM targets.

Conductive targets can be concealed by other geological conductors, "geological noise", such as:
• Lateral variations in conductive overburden.
• Graphitic bands in metamorphosed country rock.
• Altered (to clay facies) mafic-ultramaific rocks.
• Faults and shear-zones carrying appreciable groundwater and/or clay gouge.
• Magnetite bands in serpentinized ultramafics.