Abstract

The growing acceptance of the mineral systems approach to ore deposit generation
and fertile areas in the near surface (the infamous "Hand of God" example of Olympic
Dam) is forcing many companies to rethink how they conduct their exploration
programs. However, often this approach is overridden by the economics of what can
be brought into production the quickest and at the lowest cost, hence "I am only
interested in an extractable resource that is within 200m or 300m of the surface". A
resource, if of sufficient size and grade, within 200 to 300m of surface is essentially
considered to be open pitable and hence can often be brought into production in a
short timeframe. As a result, in many mining camps the majority of the geophysical
exploration that has been completed is restricted to at best 200m or 300m of
surface. An understanding of the overall mineralising system is therefore absent and
the possibility of higher grade resource at greater depth is unknown.
In this discussion the advantages of conducting a potentially deeper looking
geophysical program early on in the exploration of a project is examined from both
scientific and economic viewpoints, even if the original scope is to look shallow for
resources. The advantages of applying deeper looking geophysical methodologies
early in an exploration will be discussed with a view to the advantages, limitations and
overall exploration cost. This is a topic that is not addressed in most academic
programs. Often the prospect of looking deeper is not considered outside of some
well known mining camps (Sudbury, Athabasca Basin, Witwatersrand Basin,
etc.). However the quest for additional resources to support increased demand for
many minerals is requiring deeper exploration under cover. Examples of the benefit
of looking deep early in exploration are provided with respect to fiscal optimization.