Selective fragmentation for geochronology

In the world of geological analysis, sample preparation is critical. The ability to extract minerals of interest, like zircons, for geochronology studies is key to the success of a project.

At Curtin University, WA, Dr Tanya Claridge’s sample preparation work using electrodynamic fragmentation underpins her colleagues’ ability to analyse samples further with highly complex and sophisticated analytical instruments. Dr Claridge works in Curtin’s Department of Applied Geology, where she carries out valuable research that helps exploratory mineralogists locate ore deposits of commercial value.

Dr Claridge’s work currently focuses on selective fragmentation using SelFrag Lab laboratory batch equipment, which she has used to process a vast array of geological samples. The system has achieved good results in almost all cases using pulses of high voltage that are sent through materials, cleaving them apart along phase boundaries. The advantage of this technology is that individual grains effectively fall away from one another, while other techniques indiscriminately break down all particles.

Geochronology studies require collection of small and scarce zircon crystals for dating purposes. The SelFrag has proven to be invaluable here with its ability to liberate, preserve and concentrate zircons. This in turn increases the yield of useful material, making the zircons easier to locate and analyse.

On a more international scale, Dr Claridge’s work was crucial to the analysis of meteorite impact remains from Scotland. The SelFrag was able to effectively liberate zircons from attached minerals while keeping surface features of grains intact. This is important because the zircons have what she describes as “gnarled, lumpy, fractured aspects” to them. These surface features hold a lot of important data and these features are all but destroyed using conventional crushing and grinding.

“The SelFrag was able to preserve the shocked crystals such that yield of useful crystals was much greater, allowing my colleagues to identify the oldest known occurrence of this mineral at the Stac Fada impact site,” Dr Claridge said. “This is important because it breaks ground for future applications in using the presence of reidite as a proxy to locate even older impact events. In fact, this project would not have been possible without the SelFrag.

“I’ve been using the SelFrag for over two years now and the novelty of electrocuting rocks still hasn’t worn off. It is also much more convenient compared to traditional techniques as it is quick, simple to use, doesn’t require much cleaning and doesn’t introduce contaminants, which is very important. Also, it doesn’t generate dust, making it safer from a health perspective.”