2016/2017 Season:
| Date | Speaker | Talk | Abstract |
| April 5, 2017 | Jim Greig, CEO & President, Crystal Exploration Inc. | Exploring Forgotten Diamond-bearing Ground in the North Slave Craton | The talk will review near-term exploration plans for the North Slave Craton area around Muskox and Jericho pipes. The ground abandoned by Shear Diamonds has been taken by Crystal Exploration Inc., a Canadian public company traded on the TSX Venture Exchange. The advanced N Slave projects hold near $100 million in past exploration expenditures that includes extensive geophysics, till sampling, kimberlite indicator minerals (KIMs), diamond indicator minerals (DIMs), bulk sampling and drilling. The Muskox Kimberlite Pipe is Crystal’s most advanced asset with large tonnage (non NI43-101, >16mt) potential with grades near 0.50 cpt. Future exploration plans include drilling new high-priority discovery targets during the summer 2017. Crystal has identified 6 anomalous magnetic targets (high & low) that is supported by KIMs and pick results and additional 12 areas for spring ground geophysics that could provide more targets for drilling. |
| February, 28, 2017 | Matt Gaudet, Stornoway Diamond Corporation | The Principal Role of Silicic Crustal Xenolith Assimilation in the Formation of Kimberley-type Pyroclastic Kimberlites | Our detailed petrographic studies of pipe-infilling pyroclastic kimberlite at the Renard 65 kimberlite pipe, Quebec, Canada, provide insightful new evidence on the role of silicic crustal xenolith assimilation in the formation of Kimberly-type pyroclastic kimberlite (KPK) rock types. The results from our extensive petrographic characterization of 700 m of drill core from four separate drill hole intersections in the Renard 65 pipe suggests that the pyroclastic KPK textures and the interclast matrix mineralogy are a result of hybridization of the kimberlite magma due to reactions with granitic and gneissic crustal xenoliths. The reactions demonstrate that the assimilation of crustal xenoliths and contamination of the kimberlite magmas primarily by Si result in the enhanced degassing of magmatic volatiles during emplacement, and stabilization of the hybrid interclast matrix microlitic assemblage diopside + phlogopite + serpentine over the non-hybrid assemblage calcite + phlogopite + serpentine. At subsolidus temperatures, the formation of metasomatic coronas on crustal xenoliths may record evidence of deuteric olivine serpentinization and subsolidus compositional modification of groundmass spinel. The formation of KPK rock types in Renard 65 and associated rock types with textures intermediate between coherent and pyroclastic reflect the spatial distribution of silicic crustal xenoliths within the magma during emplacement and crystallization. Strong correlations are observed between crustal xenolith modes and kimberlite rock textures for other KPK pipes reported from Gahcho Kué and Renard. These results may further indicate that the different mineralogy and textures of Fort à la Corne-type and Kimberley-type pyroclastic kimberlites may be significantly influenced by the extent of assimilation of silicic crustal xenoliths driving the behavior of the kimberlite magma and exsolved magmatic volatiles during emplacement. |
| January 26, 2017 | Dr. Graham Pearson, Professor, Canada Excellence Chair, University of Alberta | The Complex History of the Mantle Roots Beneath the Slave Craton and Surrounding Regions | The talk summarizes the available age and P/T data for mantle xenoliths from a N-W traverse across the Slave craton (Gahcho Kue - Ekati/Diavik - Jericho - Artemisia) that reveal a complex spectrum of over-printing and possible lithospheric replacement going North. Data for Victoria Island, Darnley Bay and Dharma arel be presented and evaluated in terms of the likely presence of cratonic mantle beneath these regions. The data from mineral concentrate from the "Interior Platform" region, West of the Slave craton constrain its diamond potential. |
| Dec 7, 2016 | Dr. Peter Winterburn, Professor, and Erika Cayer (M.Sc. Geology Candidate), MDRU, University of British Columbia | Direct Detection of Drift-Concealed Kimberlites Using Surface Geochemistry Integrated with Landscape Evolution | Regional scale kimberlite exploration techniques including indicator mineral dispersal trains, geophysics and remote sensing, inevitably produces a plethora of potential targets for subsequent evaluation. A variety of geochemical techniques have been proposed for surface evaluation of targets. The first part of the presentation will review the available commercial techniques, their exploration rationales and applicability, in addition to discussing potential other techniques undergoing research and development. The second part will present results from a surface study at the DO-18 kimberlite, NW-Territories. Results from a detailed study of soil geochemistry above the DO-18 kimberlite (Peregrine Diamonds) demonstrate the potential to apply conventional surface geochemical techniques coupled with surface material mapping and landscape evolution models to the evaluation of discrete targets. Hydrocarbons were evaluated to characterize the type and abundance of complex hydrocarbons above the kimberlite relative to above the host granitic gneiss. Results show a dispersion of Nb, Ni, Mg, Ce, Cr and Cs from directly above the northern part of the kimberlite to the edge of the sampling grid following glacial dispersion. SGH-hydrocarbon results exhibit a similar pattern in light-alkyl benzenes. Fp-XRF data repeats the pattern in all elements except Mg, where the concentrations are too low for reliable detection. In the southern half of the grid, at a lower topographic level, geochemical responses are considerably more subtle. It is hypothesised that anomaly formation in the till followed standard glacial dispersion in the down ice trend. |
| Nov 8. 2016 | Dr. Jennifer E. Pell, Chief Geoscientist, Dr. Herman S. Grütter, Vice President, Technical Services, Peregrine Diamonds Ltd. | Comments and Observations on Public-Domain Micro/Macro Diamond Datasets | On March 3, 2003, the Canadian Institute of Mining, Metallurgy and Petroleum (the CIM) published a 6-page document entitled “Guidelines for the Reporting of Diamond Exploration Resultsâ€. The guidelines standardized recommended reporting of total diamond liberation results (i.e. caustic-fusion or similar data) to thirteen sieve classes ranging from 0.105 to 9.5 mm square-mesh. Over the intervening thirteen years up to today, many such “microdiamond†data sets from global diamond exploration projects have been publicly disclosed. Some of these same projects have now also matured to the point where round-aperture sieve data for commercial-sized diamonds from bulk samples have also been publicly disclosed. The resulting public-domain micro/macro diamond datasets form the backdrop to this VKC talk. Without delving too much in the dark science of “log-transformed spit-oe-ee†or “es-efdee†space, we intend to present examples that illustrate: • Diamond size distributions for two typical (reference) kimberlites in the NWT; • Coarser-than-reference diamond size distributions; • Similar-to-reference diamond size distributions; • Somewhat finer-than-reference diamond size distributions; • Substantial grade drop-off at commercial sizes; • Under-sampling effects (debatable since “the truth†remains unknown); • Some “grade forecasting†perils. If time permits, we will also look at: • some aspects of micro/macro diamond data for known low(ish) grade kimberlites; • Ultra-fine diamond size distributions. |
| 7 Oct 2016, "Double Bill" presentation | Dr. Luke Ootes, Senior Minerals Geologist BC Geological Survey | The Archean – Paleoproterozoic Evolution of the Western Margin of the Slave Craton and its Influence on On-craton Diamonds | It is no secret there are diamonds under the Slave craton. But are they everywhere in the Slave mantle? Through new bedrock mapping and associated studies, we have recognized that the Wopmay orogen may have played a significant role in the distribution of diamonds. We predict that the area of the Slave west of ~114 W may be diamond-sterile, although the area contains the same crustal attributes as the rest of the craton. The orogen is Paleoproterozoic in age, but contains significant amounts of Slave-derived Archean basement rocks. These, along with overlying and intruding Paleoproterozoic rocks were penetratively deformed and metamorphosed during the Paleoproterozoic, whereas the Slave craton was not. The rock record in Wopmay orogen preserves this history and includes initial rifting of the western margin of the Slave craton, a now-recognized second rift event, and compression that was driven by subduction and development of a continental-arc like environment now preserved as the Great Bear magmatic zone. During this Paleoproterozoic orogeny the crust of the western Slave craton was spared from thermal and metasomatic overprints, but it is likely the mantle of this area was not. A composite model of Paleoproterozoic extension and subduction-driven convergence accounts for the nature of the crustal transition between the Slave craton and Wopmay orogen, and may hold the key to why the western Slave craton may be diamond-sterile. |
| 7 Oct "Double Bill" presentation | Dr. Maya Kopylova, Professor, UBC | The Role of Subduction in the Distribution of Eclogite Below the Slave Craton | We reconstructed the spatial distribution of eclogites in the cratonic mantle based on thermobarometry for ~ 240 xenoliths in 4 kimberlite pipes of the Slave craton, Jericho and Muskox (northern Slave) and Diavik and Ekati (Central Slave). The majority of Northern Slave eclogites of the crustal, subduction origin occurs at 110–170 km, shallower than in the majority of the Central Slave crustal eclogites (120–210 km). The identical geochronological history of these eclogite populations and the absence of steep suture boundaries between the central and northern Slave craton suggest the lateral continuity of the mantle layer relatively rich in eclogites. We explain the distribution of eclogites by partial preservation of an imbricated and plastically dispersed oceanic slab formed by easterly dipping Proterozoic subduction. The base of the depleted lithosphere of the Slave craton constrained by thermobarometry of peridotite xenoliths coincides with the base of the thickened lithospheric slab, which supports contribution of the recycled oceanic lithosphere to formation of the cratonic root. Its architecture may have been protected by circum-cratonic subduction and shielding of the shallow Archean lithosphere from the destructive asthenospheric metasomatism. |
Past meetings 2012/2014 Season
Past meetings 2015/2016 Season