Final webinar closes Overberg Geoscientists Group’s series on Barberton gold deposits


The fifth and final episode aired in a series of five free weekly webinars hosted by the geoscience collective Overberg Geoscientists Group (OGG), in conjunction with the non-profit organization Geological Society of South Africa (GSSA).

During the last webinar in the series, which took place on March 31, the professor from the universities of Melbourne and Stellenbosch Neil Phillips gave a presentation on “The Application of Archean Gold Weathering to the Witwatersrand Goldfields” to a group of fellow geologists and other interested parties.

The weekly webinar series, which has been running every Thursday at 10:30 a.m. on Zoom since March 3, aimed to capitalize on significant advances at the gold deposits in Barberton, Mpumalanga, under the leadership of the University of Stellenbosch Alex Kisters – who became a recipient of the Draper Memorial Medal in November last year for his work and leadership in researching greenstone gold mineralization.

The Barberton area is characterized by high-grade gold reefs that have been mined continuously for over a century. The Barberton greenstone belt has produced approximately 11 million ounces of gold since its discovery.

The webinars reviewed the intimate relationships between fluids and many crustal processes, including partial melting, metamorphism, deformation, weathering, and ore formation.

“Like so many rapid scientific advances, the introduction of this new view of crustal fluids heralded a period in which there were virtually two geological languages ​​based on background and formation,” Philips explained.

He said that traditionally rocks were considered solid and dry, and they cracked under stress to compensate for an ore body. The alternative view emphasized the heat that generated fluid and new minerals, the migration of that fluid through a network of structures, the deformation driven by high fluid pressures and controlled by rheological contrasts and that all of this crustal activity may include a major gold forming event.

Much of the evidence for all of this is contained in assemblages of weathering minerals, he added.

Kisters has previously stated that it is extremely important to recognize the intimate relationships between structure, fluid movement and weathering by applying modern geological technologies and interpretations in greenstone and other gold deposits, and , thus, to unlock new gold economic horizons in old deposits.

Phillips said that over the past 50 years there has been a “massive” shift in geological thinking regarding weathering and its relationship to fluids, structure and metamorphism.

Crustal fluid flow is no longer thought of as open cracks from top to bottom, and structural geology is not simply the measurement of fault displacement, he added.

The webinar series highlighted how weathering is integral to the formation of many ores and that metamorphism goes far beyond the estimation of pressure and temperature. The mineralogy and geochemistry of the whole rock intertwine and influence how the rocks deform. Thermal energy, fluids and deformation connect all these domains.

The OGG and GSSA believe that a better scientific understanding of these issues, which was the rationale for the webinar series, could lead to more successful exploration and mining.

The five-part webinar series was moderated by Phillips – all episodes were open to industry, explorers and the general public, and sought to highlight new research in Barberton and other well-known gold provinces. known.

All webinar episodes were recorded and made available on the GSSA YouTube channel for on-demand viewing at no charge.

On March 3, “Introduction to the Presentation Series: Fluid Rock Wall Weathering in Greenstone Gold Deposits” was presented by Phillips.

March 10 featured a presentation on “Structural Parameters and Alteration of Barberton Gold Deposits” by Tect Geological Consulting Geoscientist caitlin jones.

On March 17, Kisters gave a presentation on “The Barberton Gold Deposits as Examples of the Interaction of Structure and Weathering”.

Then on March 24, economic geologist Julien Vearncombe presented “Optimizing the Use of Structural Geology in the Gold Industry”.

The final webinar in the series was Phillips presenting “Applying Archean Gold Weathering to the Witwatersrand Goldfields” on March 31.

Exploration, Evaluation and Mining Geologist Dr. John Bristow said there will soon be more webinars on other topics.

For more information on the webinar series, contact Bristow at [email protected] or Hennie Greef at [email protected]

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