To: Cogito Ergo Sum who wrote (25726 ) 12/18/2003 5:37:27 PM From: E. Charters Read Replies (1) | Respond to To be absolutely even handed, there are lots of wide scale breccia zones out there that add up to fair tonnage, as in the CDN hypothermal gold deposits of the Archean. Some shear zones and breccia zones with ladderwork veining are big. They however at these grades need huge. Transform and thrust fault structures can run for hundreds of miles. But they have to be mapped as such. You measure two things, permissive structural evidence which is detected as amount of fracture filling and tectonic evidence or orogeny -and- degree of alteration in surrounding rocks. A third thing that adds to the evidence is the size or multiplicity of related intrusions. Sometimes this evidence changes dramatically with drilling. All this can be done without electrical back up, which can be deceiving as to width components at depth and does not predicate valuable mineralization. A case in point is Ursa Major who has also drilled barren anomalies within the very structure their ore-like zones are in.
