North of 60 Mining News - The mining newspaper for Alaska and Canada's North

Pebble Partnership copper gold molybdenum mine project Alaska Northern Dynasty NAK NDM

By Shane Lasley
North of 60 Mining News 

Geophysics reveal deep targets at Man

Pure Nickel plans to drill targets in large conductive bodies located below two areas of its nickel-copper-PGE property in Alaska

 

January 17, 2010



During their first exploration season as joint venture partners at the Man nickel-copper-platinum group element project in Interior Alaska, Pure Nickel Inc. and Itochu Corp. said they discovered compelling new targets to investigate in 2010.

Tokyo-based Itochu and Toronto-based Pure Nickel originally set a US$ 4.4 million budget to support a 2009 exploration program at Man. The partners later added US$500,000 to the budget in order to complete a 2,722-line-kilometer Z-Axis Tipper Electromagnetic airborne survey.

Pure Nickel said the 4,200 meters of drilling and extensive geophysical program make 2009 its most in-depth exploration season since the junior began investigating the 750-square-kilometer-, or 290-square-mile,-property in 2007.

Geophysics key in 2009

The geophysical program was the key component in the 2009 exploration program at Man. To gain a better understanding of the nickel-copper-PGE property, the partners employed four types of electromagnetic and magnetic surveys:

ZTEM (Z-axis Tipper Electromagnetic system) survey - Recent 2-D inversion sections have identified, at depth, the shape, structure, and conductive zones of the mafic and ultramafic intrusions at the Alpha and Beta complexes.

Ground and airborne magnetic surveys - These surveys are helping to define the magnetic bodies below surface that often correlate to the ultramafic and mafic rocks on the property. Also, 3-D inversions of these surveys are employed to help determine the location of the form, internal structure, and feeder dykes associated with the intrusive bodies.

Fluxgate TEM - This ground-based EM technology allows for a deep search of high conductance bodies commonly associated with nickel-copper sulfides that have been missed by previous survey methodologies. This was the first instance of this proprietary, long-time-constant, time domain electromagnetic survey being used in North American nickel exploration.

Borehole EM Survey - This survey detects conductive anomalies within, beside and below the drill hole in which it is lowered. The BHEM aids in the correlation with the fluxgate and other surface surveys, providing a more accurate location of the conductors.

Pure Nickel said the combined use of the four geophysical tools revealed anomalies it characterized as "deep, large and very compelling."

The junior said the fluxgate TEM was deployed extensively through the latter half of the exploration season. Pure Nickel's use of this technology provided its exploration team with the ability to identify electromagnetic anomalies at depths greater than 800 meters.

"ZTEM is a big-picture tool. The fluxgate TEM is more surgical," said Pure Nickel President David McPherson.

McPherson told Mining News that the use of down-hole surveys was able to substantiate what was discovered with the deep-reaching ground-based geophysics.

Interesting potential

The explorer completed three holes at the Alpha Complex and four holes at the Beta Complex located about eight kilometers, or 5 miles, south of Alpha. The company struck disseminated nickel in six of the seven holes drilled, but massive sulfides were not hit with the 2009 program.

The best assay results came from the Beta Complex. At a depth of 150.7 meters, hole PNI-09-024 intersected 205.6 meters containing 0.189 percent disseminated nickel. At a depth of 533 meters, hole 24 cut an additional 135.5 meters, averaging 0.228 percent nickel.

Copper, platinum and palladium also were present. The company said an interpretation of the assays indicates the presence of a disseminated nickel-copper-PGE concentration buildup extends beyond 600 meters in PNI-09-024 and over 1000 meters in PNI-09-025.

Though these holes did not hit the massive sulfides that the explorer is seeking, it said the relationship between the disseminated mineralization and sulfides is encouraging.

"When you see what the sulfide content is, and this mineralization in a low-sulfide environment, then you speculate on what you would see in a massive sulfide environment and that is obviously the target, McPherson said. "If that mineralization carries the same relationship as it moves to a high-sulfide environment then the metal content potentially could be extremely interesting."

Deep targets

The geophysical program identified deep conductors under both the Alpha and Beta complexes. Pure Nickel was particularly excited about a deep anomaly at the Beta Complex. The junior hopes these deep conductive bodies could be the massive sulfides they have been seeking.

The explorer tried to tap the deep conductor with hole PNI-09-025, but fell short of reaching its target due to the structural limitations of the drill. The hole was terminated at 1,066 meters.

The down-hole geophysical survey showed an increasingly large response toward an anomaly below the hole's final depth.

"We probed the hole at multiple depths, substantiating what the fluxgate TEM had told us at the beginning," McPherson said. "1,066 meters is where we had to end the hole, we were seeing a significant anomaly below us."

A similar deep target has been discovered at the Alpha Complex. Identifying the deep conductor with ground-based geophysics, the company pinpointed the target with a borehole EM probe down two historical holes. This target lies below PNI-07-001, the first hole Pure Nickel drilled at Man.

Drilling deep in 2010

Pure Nickel said it plans to drill these deep targets when it returns to Man in 2010.

Equipped with a larger drill, the explorer wants to go back down PNI-09-025 and continue the hole to the area identified with geophysics. If the first hole looks promising, the company plans to use a wedge in order to drill the deep zone in several locations from one setup.

"Assuming that we get what we hope we are going to get, then we are going to use a wedging technique off of 25 to start to better understand the scale of that zone," McPherson said. "We could have a drill occupied there for a significant period of time if we are right."

A similar method is being considered for the deep Alpha Complex target.

McPherson said the company plans to drill a new hole near PNI-07-001, which bottomed out in mineralization at a depth of 659 meters. The explorer expects to intersect the deep zone at about 1,000 meters. Depending on what is discovered with the first hole, a wedge also will be used at this target.

Decision time for Itochu

As part of the JV agreement, Itochu has an option to opt out of the Man joint venture at the end of 2009 and again at the end of 2013.

The Tokyo-based mega-corporation has invested about US$6.5 million on the project since it joined Pure Nickel late in 2008. If the Japanese firm decides to continue the partnership, it has the opportunity to earn up to a 75 percent stake in Man Project by investing US$40 million in the project.

Pure Nickel's technical team recently returned from Tokyo where it presented the analysis of the results from the drill-hole geochemistry and new geophysical surveys that were utilized during the drilling program.

"Our Japanese partners were very active in the program, in the sense that they had people on site most of the season," McPherson said.

McPherson said the Japanese corporation has until the end of March to study the results from the 2009 program and decide whether or not to move forward with further exploration at Man.

 

Reader Comments
(0)

 
 

Our Family of Publications Includes:

Powered by ROAR Online Publication Software from Lions Light Corporation
© Copyright 2019