Recently I have had the opportunity to attend a core logging course organised by IAEG (Irish Association for Economic Geology) and hosted by Boliden, Tara Mines. The course was dense and helpful and most importantly, included actual core logging. Below you can take a glimpse of how the corestore looks like from the inside (Fig. 1).
The day started with presentations with generally useful information, beginning from how a core is acquired (i.e., equipment and machinery) to the kind of information that more or less everybody is partially aware of, but in case of an emergency, we can still blackout. This included Health and Safety matters, such as how to dress (brightly) and behave in a drilling site (Do not startle people! There is constant background noise generated by the machinery.), how anybody should literally anticipate an accident and how to act when that happens. Of course, the licence to operate could not be ignored, as it is common that the future drilling sites might be located in somebody else’s property. Lastly, quality control was the final part before we focused in actual cores.
Real core logging followed he very cold corestore. The participants were shown cores with different diameters, a factor that had also been previously discussed (pros and cons of the different diameters). So even though the logging is done using tablets nowadays, we were split into groups of 3-4 people and we used traditional paper form to fill out with any information we could deduct from the part of the core we had to log. Based on what the geologists working there had told us, the core was divided in different stratigraphic sequences, and we had to decide their limits by using fossils or other sedimentary structures (Fig. 2).
Later we were given some details about the equipment they use to cut cores in half (one part is kept for potential future use, while the other is used for analysis) with diamond saws (Fig. 3).
After all teams had finished logging and discussing their observations with the geologists, we moved to another core set, which was actually sphalerite-rich with some galena (Fig. 4). Senior geologists talked to us about the exploration policy in the area, how they decide where they will drill next, and how they use software for 3D modelling.
The last part of the course was that the stratigrapher Mike Philcox, wanted to add, as he has been working in Tara for many years, and it was impressive how well he could distinguish all the geological features in the cores!
Overall, the course has been very useful and our hosts were very hospitable!