Say ohm

The ohmmapper tool has helped Aurora Geosciences navigate an often challenging landscape

by Jessica Kirby
Gravity geophysical survey at Kennady North Project, Kennady Diamonds Inc.

A technician conducting a gravity geophysical survey at the Kennady North Project of Kennady Diamonds Inc. — Photo courtesy Louis Rosenthal

Kennady Diamonds’ exploration focus is on the 100 per cent controlled Kennady North project, located immediately adjacent to the De Beers/Mountain Province Diamonds Gahcho Kué diamond mine in Canada’s Northwest Territories. The project hosts four known kimberlites—Kelvin, Faraday, Doyle and MZ—as well as numerous other geophysical exploration targets.

With full management responsibility through Kennady Diamonds, Aurora Geosciences initiated the exploration work on the area adjacent to Gahcho Kue Mine back to Mountain Province—a 61,000-hectare area—back in 2012.

“We have completed all of the geological and geophysical surveying work along with managing all of the diamond and reverse circulation drilling and logistical work for this program since its inception,” said Gary Vivian, president of Aurora Geosciences Ltd.

The company uses in-house proprietary inversions to look at data, and established various high-resolution geophysical techniques to recognize smaller bodies.

New Kelvin K2 Camp completed early 2015 near Kelvin kimberlite deposit, Kennady North Project, Kennady Diamonds Inc.

The new Kelvin K2 Camp completed early 2015 near the Kelvin kimberlite deposit at the Kennady North Project of Kennady Diamonds Inc. — Photo courtesy Liam Fowlie

Aurora Geosciences’ gravity processing software allows quick turnaround in the field. The company’s proprietary ohmmapper tool quickly evaluates kimberlites and their resistivity responses. 

3D RC till sampling program at Kennady North Project, Kennady Diamonds Inc.

3D RC till sampling program at Kennady North Project, Kennady Diamonds Inc. — Photo courtesy Gabriel Fortin

“One of the things we have learned over the years is that high resolution surveys can help enhance small bodies and discrete bodies that have little change in geophysical ‎character from the country rock,” said Vivian. “It isn't always accurate, but they are tools that are far more accurate and useful than coarser surveys. Higher grade deposits can be found with this type of surveying, which can help make a smaller body economic.”

The ohmmapper tool measures resistivity differences in the underlying rocks. It can be towed behind a snowmobile, providing significant areas of coverage in a single day. Hauling in-line receivers and transmitters and spreading the distances between transmitter and receiver allows for ‎deeper penetration.

“Traversing lines in perpendicular directions allows a 3D model to be built using this survey design,” said Vivian.

Aurora Geosciences is no stranger to work in northern Canada. The company has been involved in diamond exploration since 1991 and the first discovery at Misery.

“We have done work for all of the majors and most of the juniors, and have worked and continue to do work for Ekati and Diavik,” said Vivian. “We did most of the original geophysics on Snap and still work at Gahcho Kue.”   

Its proprietary technology developments have helped Aurora Geosciences navigate an often challenging landscape; a case in point is the body at the Kennady project that dips 100 metres underneath cover rocks, making it difficult to trace.

Analyzing kimberlite drill core at Bob Camp, Kennady North Project, Kennady Diamonds Inc.

Analyzing kimberlite drill core at Bob Camp, Kennady North Project, Kennady Diamonds Inc. — Photo courtesy of Aurora Geosciences Ltd.

The company was able to meet the challenge with drilling. There is no geophysical tool designed to trace a pipe-like horizontal body such as this, but Vivian believes the ohmmapper may do the trick if it can be redesigned to look deeper.

“This is a very irregular shaped body,” said Vivian. “There is nothing like it anywhere that we know. The emplacement of this body should open eyes and minds to the possibilities these complexes are hard to find and folks need to pay attention.” 

The technology’s development is timely, said Vivian, as deeper, irregularly shaped bodies are likely the future of mining.

“If people who were chasing kimberlites in the Slave Province back in 1991 and 1992 think exploration is the same, they will be making some of the same mistakes all over again,” he said.

3D Conceptual Geological Model of the Kelvin Pipe-like Body, Kennady North Project, Kennady Diamonds Inc.

3D conceptual geological model of the Kelvin Pipe-like Body, Kennady North Project, Kennady Diamonds Inc. — Photo courtesy Aurora Geosciences Ltd.

“It is fairly clear to us that kimberlites like Kelvin are likely out there and folks need to pay attention to what the historical data is telling them. For example, the Kelvin Kimberlite has, essentially, a non-existent KIM (kimberlite indicator mineral) train.”

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