The Exploration Search Space - a concept to help improve discovery rates

We often hear about the lack of mineral discoveries in recent years, especially relative to exploration expenditures. We seldom hear about exploring new “Search Spaces”, which in a nutshell means searching in a different way/area than others, as described by Jon Hronsky.

A new Search Space can open up for a variety of reasons, including geopolitical changes, growing demand for particular metals, advances in exploration technology, and new understanding about the geology of ore deposits, or even entire geological provinces.

A recent example of a new search spaces opening up due to geopolitical changes is the Arabian Shield. The KSA government used to be focused on petroleum exploration and production, but in recent years they made strategic decisions which led to a big increase in mineral exploration activities.

Pegmatites are an example of a Search Space that opened up due to growing demand for lithium. These geologic features can literally be seen from outer space, but they were not interesting as exploration targets before, because Li demand was lower.

The Landsat-4 satellite showed how new exploration technology can open up a new search space. The newly added spectral bands 5 & 7 (compared to previous Landsat satellites) allowed for the detection of alteration zones at surface for the first time.

The satellite was launched in 1982. In the following years, this led to the discovery of numerous deposits, including the recognition of the porphyry potential at Collahuasi & Ujina, along the Domeyko Fault Zone in northern Chile (as described by Sabins in 1999).

A good geological example is the improved understanding of the zoned alteration mineralogy of porphyry deposits. David Lowell (along with Guilbert) published an article in 1970, describing this zonation in a scientific publication for the first time. Lowell had used this model in 1965 in Arizona, to discover Kalamazoo, the “missing half” of the San Manuel porphyry. The combined deposit turned into the biggest underground mine in the world by the 1980s.

?The main reason for focusing on new search spaces is that the biggest discoveries in a search space often happen early on. Large deposits generally have the biggest, most obvious signatures, which are more likely to be recognized early on during exploration than smaller ones. In his article, Hronsky used Olympic Dam as an example, a deposit so big that it was visible on continental-scale gravity data.

Another good example of this dynamic was the application of the porphyry alteration model in Chile, by the same David Lowell. He led a big campaign, exploring for big deposits where the mineralization was hidden under post-mineral cover (Cenozoic gravels).

Alteration mineralogy was visible at surface, in a region known for big Porphyry Cu deposits. The “Atacama Project” started in 1978 and in 1981 led to the discovery of Escondida, which for many years has been the biggest Cu mine in the world.

A recent example is Kamoa-Kakula (and the Western Forelands) in the extension of the Central African Copperbelt. Due to a geological change, this part of the belt was previously thought not prospective for sediment-hosted Cu (& Co) mineralization. Until Ivanhoe showed otherwise…

To raise the odds of exploration success, it is important to explore new search spaces, not focus on the same old, tired ones. Unfortunately, a lot of the exploration expenditure these days is spent on “advanced projects”, drilling more holes into deposits that failed in previous cycles. While this is a guarantee for drilling significant intersections of good grades of mineralization, the likelihood of finding a Tier-1 deposit this way is close to 0. This is one of the main reasons for the recent lack of discoveries, even though expenditures have been high.

The original Exploration Search Space description by Jon Hronsky is only a couple of pages long. Give it a read, and make sure you explore new search spaces, or invest in companies that do, to raise the odds of significant discoveries.