Northern Shield Resources

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Northern Shield Resources
Summary of drill result interpretations
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Forward Looking Statements
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Cu/PGE
The diagram shows PGE depletion trends (Cu/PtPd)
for the Bushveld Complex and the Highbank Lake
Intrusion. Geologist use Cu/(PtPd) as a gauge
to measure depletion because Pt and Pd are
scavenged much more efficiently than Cu by any
sulphide droplets in the magma. Note how the
upper portion of the Bushveld Complex is depleted
in PGEs, i.e., it has less PGEs than the mantle
from which the magma was sourced. The depletion
ratio gradually decreases down through the layers
in the intrusion to a point where it equals
mantle value and then within a very short
distance rapidly becomes enriched. The Merensky
and UG-2 PGE- reefs occur very near this
cross-over level. A very similar trend is
exhibited in the data from Highbank Lake where
the depletion ratio gradually decreases down
through the sequence and then rapidly becomes
enriched at the very bottom of drill-hole
07HB-01. This suggests that much more significant
PGE mineralization may be within a few tens of
meters from the bottom of this drill-hole.
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Cu/Pd
The diagram shows Pd depletion trends for 4 other
PGE-bearing layered intrusions. Note how again
the PGE reefs occur at or very near the
stratigraphic level where the rock chemistry
changes from being depleted to enriched in PGEs
(Pd).
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PtPd
The overall PGE values also give an indication of
the proximity to the main PGE reefs. PGE
concentrations in the Main Zone of the Bushveld
(grey area) are typically around 10-30 ppb and
rarely exceed 100 ppb until the Critical Zone is
reached just above the Merensky reef. The
Highbank data shows PGE values over 30 ppb
becoming much more common in the lower portion of
drill-hole 07HB-01 and values greater than 100
ppb are only seen in 07HB-01 and 05.
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Cr/V
Chrome/vanadium ratios are useful in determining
how primitive the rock layers are. Generally, Cr
becomes more abundant lower in the stratigraphy
(more ultramafic) while V decreases. Cr/V ratios
are also useful in highlighting stratigraphic
levels at which magma replenishment has occurred.
Bushveld Cr/V ratios are relatively constant,
near 1 for much of the Main Zone but start to
rise rapidly a few hundred meters above the
Critical Zone. The data from Highbank Lake shows
a similar trend with Cr/V ratios of 1 or less for
much of the Main Zone that increases noticeably
at the bottom of the Main Zone, as exhibited in
drill-hole 07HB-01. The last three samples taken
from the bottom of this drill hole before it
ended in a silicified fault zone display the most
primitive Cr/V ratios (8-9) seen in drill core
from Highbank Lake so far.
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Summary
The geochemical trends and the rock types
identified in the drill core to date suggest that
the bottom of drill-hole 07HB-01 is teasingly
close to the stratigraphic level where the main
PGE-bearing reef should be located. Hole 07HB-05
was drilled in an attempt to intersect the
stratigraphy below 07HB-01. However, the
geochemical trends show that this hole is not a
direct continuation of 07HB-01 (see Cr/V) and the
stratigraphy may also be over-turned (see
Cu/PtPd). Displacement along a fault located
between 07HB-01 and 05 is likely the cause of
this disruption in the stratigraphic sequence.
Future drilling will focus along strike from
07HB-01 and 05 where the stratigraphic sequence
intersected at the bottom of 07HB-01 and those
directly below come to surface and are not
disrupted by the fault.