2018/2019 Season:

Date Speaker Title Abstract
April 16, 2019

Dr. Ralph Tappert, Consultant, Hyperspectral Intelligence Inc

Kimberlites and diamonds of South Australia: A new look at kimberlite petrogenesis  Kimberlites of Jurassic age occur in various parts of South Australia, but most of the known kimberlites are located in the Adelaide Fold Belt. Although the majority of kimberlites in South Australia are barren, some diamondiferous kimberlites occur in a restricted part of the Adelaide Fold Belt cluster. These kimberlites appear to be the source of some, but not all diamonds in local placer deposits. The kimberlites in South Australia are compositionally diverse, and range from olivine-dominated varieties (macrocrystic kimberlites) to olivine-poor, phlogopite-dominated varieties (micaceous kimberlites). Correlations between groundmass mineral compositions and modal olivine abundances indicate that all kimberlites are part of a continuous spectrum of kimberlites that originated from a uniform parental melt, which is also supported by their radiogenic isotope compositions. These observations challenge current ideas about kimberlite petrogenesis, and suggest that kimberlites are just ordinary rocks that have received variable amounts of mantle contamination.
February 27, 2019

Dr. Evan Smith, Research Associate, Gemological Institute of America



Origin of Type II diamonds and their super-deep genesis

Presentation in PDF

Presentation Video

As gemstones, type IIb diamonds are prized for their blue colour, from traces of boron in the crystal lattice. From a geological perspective, these rare diamonds stand out because boron is a quintessential crustal element, so its defining presence in this particular diamond variety is unusual. A systematic search for inclusion-bearing type IIb diamonds, leveraging the grading operations of GIA, made it possible to examine multiple inclusions in 46 samples. The inclusions show that type IIb diamonds are sublithospheric, derived from as deep as the lower mantle. The proposed genetic model involves deeply subducted oceanic lithosphere, with boron ultimately sourced from seawater serpentinization. Although further work is needed, type IIb diamonds hint at a possible major pathway for water recycling into the deep mantle.
Jan 31 2019

Dr. Mike McCubbing, Supervisor of the Geoanalytical Laboratories' Diamond Services team, the Saskatchewan Research Council.



Using Diamond Characterization to Refine Micro and Macro Diamond Processing and Recovery. 

Bulk samples for both micro and macro diamond recovery are very costly, and typically only a small amount of quantitative data is collected, this is particularly the case for micro diamonds. The presentation provides an overview of standard recovery methods for micro and macro diamonds as well as other test work that can be applied to the parcels. The resulting data can supply information on the unique properties for that parcel in order to customize process flows and optimize recovery. 

Nov 6 2018 Gregory Dipple, Professor University of British Columbia.

Optimizing carbon capture and storage in kimberlite tailings for environmental benefit and operational efficiency.

Presentation Video

Ultramafic mine tailings, including those from kimberlite-hosted diamond mines, offer potential operational and environmental benefit through reaction with carbon dioxide from air and power plant flue gas. The carbon dioxide is sequestered from the environment through the precipitation of carbonate minerals, thus reducing or offsetting the greenhouse gas emissions associated with mining. Additional benefits can include tailings stabilization, dust reduction, acid mine drainage prevention, and toxic metal encapsulation. This talk presents an overview of the processes and controls on carbonation reactions within tailings at active mines with a focus on acceleration of carbon sequestration within kimberlite tailings.
Oct 3, 2018 Michelle Tappert,Consultant Hyperspectral Intelligence Inc.

Novel exploration tools: Using reflectance spectroscopy to detect hydration halos around kimberlites Presentation Video

Many kimberlite ore bodies are relatively small and the presence of overburden along with the complexities of interpreting geophysical data can make it challenging to intersect a kimberlite target during exploration drilling. However, the analysis of country rock drill core from the perimeter of several known kimberlites provides evidence that subtle alteration (hydration) halos around kimberlites exist, which can be detected using rapid and cost-effective spectroscopic techniques. Identification of these hydration halos, which are independent of country rock composition, may provide crucial information about the presence of undiscovered kimberlite in an exploration area, especially if kimberlite was not intersected during initial drilling. Preliminary estimates suggest that these hydration halos, which are most likely caused by kimberlite-derived hydrous fluids, can extend more than 65 meters into the country rocks, but their size strongly depends on the size of the kimberlite body. Narrow kimberlite dikes produce much smaller halos compared to large kimberlite pipes. In addition, hydration halos in carbonate rocks also appear to be smaller compared to silicate rocks.