Dust flux, Vostok ice core

Dust flux, Vostok ice core
Two dimensional phase space reconstruction of dust flux from the Vostok core over the period 186-4 ka using the time derivative method. Dust flux on the x-axis, rate of change is on the y-axis. From Gipp (2001).

Saturday, March 22, 2014

Scale invariance of mineral wealth--the exploration conundrum

I was dreaming when I wrote this. Forgive me if it goes astray.
Part of the reason I started this blog was to work through some ideas. Writing them and seeking comment while they are still forming seems to be an ideal use of interweb pipes.

I have written here and here about scale invariance in gold deposits--mostly on a global scale, using various data sources (pdf), including this one (pdf). What to do with this information?

The most common question is "what is the largest gold deposit left to be discovered?" Unfortunately, the answer is probabilistic. There will be a fairly low probability that the largest gold deposit still to be discovered is larger than the largest found to date. A more meaningful question might be "what is the typical size of a gold deposit that remains to be found?" Nobody seems to be interested in that one. Typical deposits are for other people to find. They are going to find the largest one.

As above, so below. Given sufficient data, the analysis can be repeated for separate structural provinces, or for particular trends. At present, there is limited interest in this approach (pdfs), but it may be because it is not completely clear how to best use the information obtained by the analysis. Mining companies don't really make decisions to investigate a general area on these sort of criteria.

Presently, most mining companies decide to get ground on wholly different criteria. They select a commodity not necessarily based on their expertise, but because the market appears to favour it. They select a locality on the basis of its current popularity (bonus points for recent spectacular discovery), political stability, the ease (or cost) of acquiring properties, their personal interest/familiarity with the region, or the availability of infrastructure. Just check the websites of some junior mining companies.

Oil companies, on the other hand, use this type of data in a process called play-based exploration. "Play" refers to a prospective area, not what the geologists do. The idea is that through studying the distribution of the sizes of known oil deposits within a field, a company will estimate the probability of discovering a pool of oil of a given size, balance that against the probable losses accumulated during exploration, and decide whether or not to proceed. This is entirely different, and separate, from the analysis of any individual prospect within the play.

An analogy within the mining industry would be to estimate the typical size of a gold deposit in a place like Kazakhstan, and using that information to make a decision about whether or not to attempt to look for ground to acquire. The mining industry is not at that point, largely because the costs of failure are nowhere near as high as similar costs in the oil industry.

Oil companies went this route as the costs of dry holes escalated over the past few decades, and they began to lose money on plays, despite having success with individual prospects. 

1 comment:

  1. Thought provoking post. Closest thing I have seen to this in mining is an old Nautilus minerals presentation comparing the size distribution of VMS deposits to the seafloor VMS deposit they had found. Nautilus's argument was that since their infrastructure was portable, they could aggregate many smaller deposits.

    See slide 12 of this presentation