In all mineral exploration, the ‘Scale Paradox’ is the fundamental factor that exploration professionals must overcome. The paradox is how to go from a global/country/terrane scale down to targeting an individual drillhole. One would think that when moving from a larger area to a smaller one, exploration would become easier, but it doesn’t; it becomes more difficult and more expensive. This is the Scale Paradox.
Historically, geological mapping was key to bridging this paradox. This allows for the definition of areas of anomalous mineralization or key lithological/alteration/structural associations on the surfaces. However, as exploration continues to look deeper, geological mapping is no longer reliable.
Explorers look for other techniques, like geophysical or geochemical targeting, all focused on reducing the Search Space and solving the paradox.
Exploration is now being driven by more and more diverse datasets, with the hope that a combination of data types can help define exploration targets.
Geologists love data and hate interpretation. We love absolutes, values, and numbers, and so explorers try to acquire more and more data. Machine learning approaches are being used to assimilate and cogitate these diverse datasets in the hopes that the computer can do much of the interpretation. There is a consistent drive to define a geochemical anomaly before critically understanding the geological history of a region. However, fundamental geological understanding and interpretation must always underpin any element of exploration, and geologists must push themselves to interpret continuously and not rely on absolutes.
A great example is in orogenic gold deposits, where exploration can be extremely difficult. These deposits have limited to no geophysical signature, limited geochemical anomalies, and are associated with tight alteration halos. This means methods that can be applied to other deposit types, like electrical geophysical surveys in massive sulphide deposits or alteration vectoring in porphyry copper deposits, do not work in orogenic gold. Luckily, these deposits form in major mountain-building events and are strongly controlled by structures therein. Using geological knowledge about how structures moved and created dilatancy illuminates exploration targets never seen and solves the Scale Paradox. This cannot be achieved simply with more and more data; fundamental geological skills remain the most important factor.
