- Advanced stage diamond project
- Located in close proximity to Rankin Inlet, Nunavut, Canada with good infrastructure
- High-grade near-surface inferred diamond resource, remains open along strike and at depth
- Outstanding diamond indicator minerals in till sampling have generated multiple new exploration targets
- Recent expansion of claims to 1664 km2
- 2017 Exploration – ongoing till sampling program of 3,500 tills from 1,000 square kilometre to test a new targets and new areas staked in late 2016
- Drill programs to test diamond kimberlite targets is planned for winter 2017-2018
Figure 1: Dunnedin’s Kahuna claims, expanded to 1,664 km2 in September, 2017
Kahuna is an advanced stage high grade diamond project discovered in 2001. It is located 25km from Rankin Inlet, Nunavut. Three main diamondiferous kimberlite dikes have been discovered, the Kahuna, PST and Notch.
Bulk sampling and drilling on the three main kimberlites has returned very high macrodiamond counts including diamonds over one carat in size. The largest diamond recovered was a 5.43 carat stone from the Kahuna dike that had been broken during the sample preparation process and was reconstructed as having an original size of 13.42 carats. The majority of diamonds are reported as clear and colourless to white, with a significant population of octahedral stones, however coloured stones have also been reported.
In July 2017 diamond recovery results from the PST kimberlite were announced. A total of 8.17 carats of commercial-sized diamonds (+0.85 mm) were recovered from 2.03 tonnes of PST, for a final aggregate sample grade of 4.02 carats per tonne.
Earlier, in January 2017 a third, 43.78 kg sample of the Notch kimberlite returned 4 commercial-sized stones (+0.85 mm) totaling 0.43 carats, for a sample grade of 9.72 carats per tonne. The largest recovered diamond was a 0.16 carat clear and colourless elongated octahedron. The aggregate sample grade recovered from 2.36 tonnes at Notch is 1.01 carats per tonne.
The dikes occur within an extensive network of largely untested geophysical targets, which are overlain by dense diamond indicator mineral trains. The Kahuna project comprises over 120,000ha of mineral claims that cover the three main dikes, plus flanking ground that covers the prospective source regions of the main indicator mineral trains and several interpreted folded greenstone belts.
Maiden Inferred Resource Estimation
In January 2015 Dunnedin released a maiden Inferred Resource estimate from the Kahuna Diamond Project (the “Project”), located in Nunavut, Canada. The estimate was prepared by APEX Geoscience Ltd. on the Kahuna and Notch kimberlites based on data from the 2006 – 2008 bulk sampling and drill programs completed by the past operator.
- A combined Inferred Mineral Resource of 4,018,000 carats of macrodiamonds at a 0.85 mm (+1 DTC sieve size) lower diamond cut-off, with an average grade of 1.01 carats per tonne (cpt), or 101 carats per hundred tonnes (cpht) derived from 3,987,000 tonnes of kimberlite resource.
- The kimberlites in the resource are exposed at surface and remain open to extension along strike and at depth. The average drill intercept at the Kahuna kimberlite was only 80 vertical metres, however kimberlite has been intersected at vertical depths of greater than 120 m and continuity at depth is supported by the available data.
- Indicator mineral trains and geophysics suggest the Kahuna and Notch have the potential to extend along strike into areas of thin sediment cover. Kimberlite has been intercepted in drilling along these potential extensions; however drill spacing was insufficient for inclusion in the resource. These areas will be a focus of future drilling.
- Only 2 of 8 confirmed significantly diamondiferous kimberlites (Kahuna and Notch) have sufficient drilling, bulk sampling and density definition work to be included in the inferred mineral resource at this time. Other drilled, mapped and sampled diamondiferous kimberlites include the PST, Killiq, and 4 additional kimberlite dikes located between the Notch and PST kimberlites (KD-13, 14, 16 and 18).
Drilling, surface bulk sampling, and micro- and macrodiamond data indicate the Kahuna and Notch are both single phase, macrocrystic hypabyssal kimberlite dikes having similar visual and petrographic characteristics throughout. Given their relatively simple internal geology, Kahuna and Notch were modeled as separate bodies and the Mineral Resource Estimate was established by applying average grades from surface mini-bulk samples within each geological model. Sensitivity analyses of the grades at both 0.85 and 1.18 mm cut-offs are presented in Table 1.
|Classification||Kimberlite||Density (t/m3)||Volume (m3)||Tonnes||Average Grade cpt (+0.85 mm cut-off)||Average Grade cpt (+1.18 mm cut-off)||Total Carats (+0.85 mm cut-off)||Total Carats (+1.18 mm cut-off)|
Table 1: Inferred Mineral Resource Estimate for the Kahuna and Notch Kimberlites
Note: The reader is cautioned that Mineral Resources are not Mineral Reserves and do not have demonstrated economic viability, and might never be converted into Reserves. Figures may not sum due to rounding. Decimal figures do not indicate added level of precision. cpt = (carats-per-tonne)
The potential diamond valuation or mining characteristics of the Kahuna and Notch kimberlites have not yet been determined. However, a 2008 evaluation of Kahuna diamond characteristics by Mineral Services Canada (MSC) describes the Kahuna diamond population as having encouraging value characteristics, with a high abundance of colourless and near colourless varieties with octahedral shapes being the dominant morphology. The Notch kimberlite displays similar diamond characteristics to Kahuna and other significantly diamondiferous kimberlites within the Kahuna Project including the PST and Killiq kimberlites.
The Company cautions that the inferred resource cannot be used to construct an economic model of the project prior to assembling a package of diamonds for valuation.
Dunnedin’s Field Programs
In collaboration with its technical adviser Dr. Charles Fipke and director Chad Ulansky, the company completed a glacial till sampling program of more than 3,000 till samples on the Kahuna property from July to September 2017. This follows a similar sampling program of 1,111 samples collected in 2016 and 218 in 2015.
Glacial till sampling recovers kimberlite indicator minerals (KIMs) that were eroded from kimberlites by glaciers and deposited down ice. This creates a train of positive till samples that can be tracked back to their original source. It is used extensively in the Canadian Arctic as a primary exploration tool leading to most major diamond discoveries, one of the most famous examples of which is Ekati.
Dunnedin’s test program utilized the same sampling and mineral ranking techniques as applied at Ekati, which can predict the potential of kimberlites to host diamonds with a high degree of confidence. The ranking employs proprietary mineral chemistry filters developed at CF Mineral Research Ltd. (CFM) under the direction of Dr. Fipke. Information on the sampling and ranking protocols is provided on this website.
In June of 2017 Dunnedin reported the identification of new kimberlite pipe targets with down-ice till chemistry matching known diamond-bearing kimberlite dikes at the Kahuna project. These are priority drill targets for 2017 that the Company believes have strong diamond potential. The drilling on these targets and other priority targets identified from the analysis of the remaining 903 samples collected in 2016 are expected in the winter of 2017/18.
Summary of Results from 2016 samples
The 2016 program was implemented to expand upon existing mineral trains and to identify additional diamond sources.
- Results received for 208 of 1,111 (19%) till samples collected in summer 2016, with results from the remaining 903 samples expected to be released in the balance of 2017
- To-date, up to seven potentially diamond-bearing kimberlite pipe targets have been identified with associated DIM dispersions in down-ice tills. Targets will be ranked for follow up exploration and drilling once all results are received. The total number of targets, and their relative strengths based on DIM content, will be provided at that time.
- Drilling of kimberlite targets expected in the winter of 2017/18.
- The Kahuna project is notable for yielding DIM chemistry associated with large diamonds recovered at producing diamond mines, including Ekati, which has been validated by recovery of large diamonds (up to 13.42 carats) at Kahuna.
- Certain chemistries of the DIMs clinopyroxene, chromite, garnet and picroilmenite are observed consistently within the diamond-bearing kimberlite dikes, and are also found down-ice from the newly identified targets.
- The geophysical signature of historically drilled kimberlite pipes generally consists of negative in-phase electromagnetic responses and variously high and low magnetic responses that are distinctive from background geology. The newly identified kimberlite pipe targets are consistent with these signatures, but require drilling to verify.
Figure 2: Kimberlite pipe targets with diamond indicator minerals (“DIMs”) in down-ice tills. Individual targets shown in insets. Magnetic total field geophysics shown. Results are from 208 of 1,111 samples received to date.