The Overberg Geoscientists Group (OGG) – a collection of likeminded retired or interested persons in the field of geoscience – in conjunction with nonprofit organisation the Geological Society of South Africa (GSSA) will present a five-part webinar series on alteration and its linkages to fluids, structures and gold deposits.

The webinars – which will be hosted on Zoom each Thursday throughout March – will be open to industry, university students and any other interested participants at no cost. 

Over the past 50 years, there has been a “massive” shift in geological thinking with respect to alteration and its relationships to fluids, structure and metamorphism, the OGG says.

No longer is crustal fluid flow envisaged as being up and down open cracks, nor is structural geology simply the measuring of fault displacement, it adds.

“Today, alteration is an integral part of much ore formation, and metamorphism goes well beyond the estimation of pressure/temperature. Mineralogy and whole rock geochemistry become intertwined and influence how rocks deform Linking all these fields are heat energy, fluids and deformation,” the OGG says, adding that it hopes that improved scientific understanding of these matters might lead to more successful exploration and mining.

The timing of the webinars aims to take advantage of the significant recent advances on Barberton gold deposits, in Mpumalanga, under the leadership of University of Stellenbosch professor Alex Kisters.

The Barberton area is characterised by high-grade gold-bearing reefs that have seen sustained mining for more than a century. The Barberton Greenstone Belt has produced about 11-million ounces of gold since its discovery.

The incorporation of examples from the gold fields of the Yilgarn Craton of Western Australia will emphasise the opportunities arising from the global transfer of ideas for exploration and mining.

“The talks will also be a further contribution and input to our general theme of highlighting the remarkable mineral endowment of [South Africa] and the dire need to revive grassroots exploration, thereby attracting new investment, drive new project and mine development, and create much needed jobs,” exploration, evaluation and mining geologist Dr John Bristow tells Mining Weekly.

On March 3, the “Introduction to presentation series: Fluid wall-rock alteration in greenstone gold deposits” will be presented by Stellenbosch University and University of Melbourne professor Neil Phillips.

March 10 will feature the presentation of “Structural settings and alteration of the Barberton gold deposits” by Tect Geological Consulting geoscientist Caitlin Jones.

On March 17, Kisters will present “Barberton gold deposits as examples of the interplay of structure and alteration”, while economic geologist Julian Vearncombe will present “Optimising the use of structural geology in the gold industry” on March 24.

Finally, Phillips will present “Applying Archean gold alteration to the Witwatersrand goldfields” on March 31.