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Wabassi/Max - SUMMARY
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The Wabassi and Max properties are located in northwestern Ontario, 60 km south of the Highbank Lake project and 100 km south of the Ring of Fire Ni-Cu-PGE and Chromite deposits. The properties are being explored for reef-hosted PGE and massive sulphide Ni-Cu-PGE deposits.
The Wabassi and Wabassi North properties are 100% owned by Northern Shield and the Max property is a 50/50 joint venture with East West Resource Corp. |
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WABASSI INTRUSIVE COMPLEX OVERVIEW
The Wabassi and Wabassi North properties were staked by Northern Shield Resources Inc. in 2007 based on the geophysical pattern observed on the magnetic survey published by the Ontario Geological Survey (OGS) in the Fort Hope area, which suggests a layered intrusion. Limited field observations and sampling confirmed the presence of cumulate gabbronorites, olivine-gabbronorites and olivine-norites, along with local layering at outcrop scale. These observations confirm that at least part of the Wabassi intrusive complex is a layered mafic to possibly ultramafic intrusion. The anomalous values of Pt and Pd (130 ppb Pt+Pd) found in one of the 3 samples analysed from the first sample collection in 2007 also confirms the potential for PGE and/or Ni-Cu-(PGE) deposits in the intrusive complex. In 2008, Northern Shield optioned the neighbouring Max Property from East West Resource Corp. Subsequently, drilling confirmed the distinct magnetic anomaly in the northern portion of the property to be a nickel, copper and PGE-enriched ultramafic (peridotite) intrusion.
The lithological and geochemical study of the Max peridotite intrusion and the Wabassi olivine gabbronorite intrusion suggests that the two are related and likely originate from the same magma source.
The average Pt + Pd and Ni content of 107 drill core samples from the Max intrusion are 45 ppb and 1600 ppm respectively, indicating mantle composition that is very fertile in nickel and PGEs. Most of the samples collected so far from the upper levels of the Wabassi layered intrusion show depleted levels of nickel and PGEs. If the two intrusions are related, as is supported by the geochemistry, a model suggesting that the Max ultramafic intrusion is the "upstream" portion and the Wabassi mafic intrusion the "downstream" portion of a continuous system can be strongly advocated. This model implies significant potential to find Ni-Cu-PGE mineralization in a conduit between the two bodies or in the lower levels of the Wabassi intrusion. |
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Four mafic-ultramafic intrusions are known to exist within the two properties.
WABASSI LAYERED INTRUSION
This is a layered mafic-ultramafic intrusion composed of olivine-gabbronorites and norites in the upper (northern) portion. To date, very little exploration has been conducted on the southern portion but it is now believed to represent the lower, and most prospective, levels of the intrusion.
WABASSI NORTH INTRUSION
Other than one drill hole, no other exploration has been conducted to date on the Wabassi North Property. Drilling intersected a variety of gabbroic rocks which may, or may not be related to the main Wabassi layered intrusion or the Max peridotite intrusion. The geophysics suggest that this body may consist of composite phases of gabbroic and other mafic/ultramafic phases.
MAX PERIDOTITE INTRUSION
Five drill-holes were completed on this target by Northern Shield in 2007 as part of an option agreement to earn a 50% interest in the property. The body is composed mostly of peridotite (harzburgite) and comprises the most primitive rocks intersected to date within the two properties. The body has high background levels of Ni-Cu-PGE. Geophysics suggests a possible feeder conduit between the Max peridotite and Wabassi North gabbro.
GABBROIC INTRUSION
An intrusion in the southern portion of the Max property (see figure above) has been mapped by the OGS as a gabbroic body, but no exploration has taken place to date on this portion of the Property.
WABASSI LAYERED INTRUSION
The Wabassi intrusion is a well-layered mafic-ultramafic complex with similarities to the Stillwater Complex in Montana, where PGEs are mined from the J-M reef. Rock-types so far identified include, olivine gabbronorites, olivine norites and norites; these are all ideal lithologies in nickel and PGE bearing systems. The intrusion is being explored for Ni-Cu-PGE massive sulphides along the contacts and in feeders, and for disseminated mineralization hosted in "reefs". |
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Based on geophysical interpretations and surface sampling, the Wabassi layered intrusion appears to be composed of two districts series, the Cyclic Series and the Layered Series.
Ongoing studies and interpretation of the Wabassi intrusion have isolated two layered sequences that will also be prospected for disseminated reef-type PGE mineralization and chromite. Disseminated mineralization and chromite are not usually detected by airborne EM surveys.
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A VTEM survey completed over the Wabassi property has detected three distinct clusters of electromagnetic (EM) anomalies (WAbassi A, B & C.) The strength of the conductors range from moderate to very strong and correspond to magnetic highs. One of the clusters of VTEM anomalies can be traced intermittently along a magnetic feature that has strike length of 2000 meters. The location and geometry of this body suggests it may represent a feeder conduit into the main Wabassi Intrusion. Feeder conduits are ideal hosts for Ni-Cu-(PGE) mineralization. Fragments of nickel-bearing pyrrhotite and blebs of primary nickel-copper mineralization were observed in core from a drill-hole completed in 2008 adjacent to one of the VTEM conductors.
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One of the VTEM anomalies at Wabassi.
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About PGE Enrichment, Precipitation and Depletion
The theory behind the mineralization process of a PGE deposit, particularly one hosted in a “conduit” or pipe, can somewhat be likened to an air-filter in the central heating/air conditioning system in a house: The air coming out of the heating/AC unit contains dust and other airborne particles. Most central air systems in houses contain a filter in the duct to remove all such dust particles before the air reaches the other rooms in the house. One might describe the air in the system upstream from the filter as being “enriched” in dust whereas the air downstream from the filter is “depleted” in dust.
Under certain conditions, the ultramafic magma pumped up from the earth’s mantle or core contains relatively high levels of PGEs (10-30 ppb) and nickel (1000-3000 ppm).
Although this magma and the rock forming from it may be considered enriched in PGEs, it is far from being economic at these levels unless a mechanism causes the PGEs to concentrate and form a mineralized deposit. One mechanism that could achieve this is to contaminate the magma with sulphur. PGEs, nickel and copper have an affinity for sulphur, such that as soon as sulphur is introduced into the magma, these metal particles attached themselves to the sulphur molecule and precipitate out of solution. Because the sulphide minerals and PGEs are dense, they tend to sink to the bottom of their host body or accumulate in traps. The sulphur has acted as a filter removing nickel, copper and PGEs from the magma as it flows along the conduit and hence the magma downstream from the filter contains very little PGEs and is said to be depleted.
Thus if one can find two mafic-ultramafic bodies formed from the same magma with one being enriched and the other one being depleted, then there is a good chance that somewhere in between, PGE mineralization may have formed.
In the case of Max/Wabassi, the Max peridotite is enriched in PGEs (average 45 ppb Pt+Pd). The Wabassi Intrusion shows signs of being depleted in PGEs (average <3 ppb Pt+Pd), which suggests that PGE mineralization may have formed between the two bodies.
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