Hello Averagejoe2013,Thank you for posting this very informative...

Hello Averagejoe2013,

Thank you for posting this very informative paper, it makes for a good reference to the formation of sulphide Nickel/Copper mineralisation. and after re-reding it, one paragraph that stands out with respect to the description in the reported intersections by SGQ, that is the section under “SulphideTextures” in the Balmoral paper, and whilst this is common with many nickel sulphide deposits other than the Grasset deposit of Quebec, and even though we have spoken about this several times before in these posts, it is worth highlighting it again here for the benefit of newcomers to this SGQ thread and as a refresher.

So, without paraphrasing the section, I will just cut and paste from the Balmoral paper as it is in the public domain. http://www.balmoralresources.com/projects/grasset/nickel-deposits-explained Nevertheless, I highlight some sections which have similarities to what we are seeing in the Cathedrals Belt holes. Cathedrals Belt seem to show superior signals in frequency and grade of mineralisation.

Again, thank you for sharing @Averagejoe2013. and Cheers.

Sulphide Textures – A Key to Recognizing and Navigating in Magmatic Nickel Systems

Ultimately sufficient sulphides will accumulate within these depressions to form nickel-copper-PGE orebodies. These orebodies are characterized by a number of distinct textural elements (Figure 3 below). Already at Grasset we have seen most of the elements characteristic of an idealized magmatic nickel-copper-PGE sulphide system.

Working from top to bottom of the system we see at the highest levels broad zones of disseminated (or interstitial) sulphide mineralization. You can think of these as individual sulphide drops frozen in place within the magma – sulphides that either didn’t have the time to sink before the magma crystallized or drops that didn’t reach sufficient size to sink. Typically this type of Disseminated Ore is seen above and lateral to the higher grade, more massive parts of the system. One of the characteristics of magmatic sulphides is that the individual sulphide grains – like the orebodies as a whole – tend to be zoned having a more copper-rich top and nickel rich base. Thus magmatic sulphide grains are typically multi-phase being comprised of separate chalcopyrite (copper-rich), pyrrhotite (iron-rich) and pentlandite (nickel-rich) phases.

A number of open pit nickel deposits are developed within these disseminated zones which tend to be more laterally extensive than the massive sulphide zones. Often nickel systems progress no further than this disseminated phase. The large Dumont nickel deposit, located 200 kilometres south of Grasset near Amos, Quebec would be an example of a large, disseminated nickel deposit which lacks appreciable semi-massive or massive sulphide zones. Drill hole GR-14-16 displayed over 65 metres of disseminated nickel bearing sulphides.

Deeper into the systems the sulphide drops begin to coalesce as they start to sink to from what is known as “Blebby” or “Globular” Ore. These “blebs” may reach several centimetres in size and range from aggregates of droplets to semi-massive sulphide “balls”. This type of texture is relatively rare, as the blebs are effectively caught in place as they falling through the magma. The photo below is from Grasset hole GR-14-22 showing classic “blebby” or globular sulphides, note the disseminated sulphide grains around the blebs. Blebs comprised mainly of pyrrhotite with lesser pentlandite and chalcopyrite in ultramafic (peridotite) matrix.

As the sulphides continue to sink we see net-textured (or matrix) ores which are the most common ore type in most high-grade nickel deposits. Here sulphides range from 5 to as much as 50+% of the rock, forming a matrix between silicate minerals. Depending on the dynamics of the magma chamber the sulphides can be thought to have sunk between and cemented together earlier formed silicate minerals or the silicates may have settled into a sulphide pool as the chamber cooled. The genesis can be argued either way but what we end up with is a “net” of partially connected sulphide grains. In some cases there is enough connectivity between the sulphide grains for them to produce weak to moderate geophysical (EM or electromagnetic) conductors. All of the mineralization styles above will typically produce I.P. (induced polarization) anomalies. As recently reported by Balmoral drill hole GR-14-25 displayed over 40 metres of net textured sulphides as show in the photo below.

Ultimately, at the base of the sequence, the sulphide grains will settle until they dominate the base of the depression and form massive nickel-rich sulphides.These are typically the richest parts of any magmatic nickel system but massive nickel sulphide bodies are surprisingly rare, suggesting most systems crystallize before allowing the time for, or don’t have the flow dynamics or geometry to generate, formation of massive sulphides. The presence of massive nickel sulphides in (our third hole at Grasset (GR-14-17)was) thus very encouraging. Typically the more massive parts of the system are moderately to highly conductive as we have seen at Grasset. --- Substitute what is in the bracket in black text with (The Cathedrals Belt is)

Structural Modification

Following the formation of a nickel sulphide zone subsequent activity can modify these original textures. In many cases subsequent magma pulses into the host intrusion, or even new ultramafic volcanic flows, can partially or completely erode the early formed sulphide zones. In some cases, as in the Raglan area of northern Quebec, subsequent magma pulses can lead to the formation of multiple “stacked” nickel zones within the host intrusive sequence as shown in the diagram below. Early evidence at Grasset indicates potential for a similar scenario with nickel mineralization being observed at multiple levels within the Grasset ultramafic complex. In drill hole GR-14-25 a massive sulphide zone at the top of the net-textured mineralization would appear to relate to a second magma pulse, later than the one forming the net textured mineralization, which has cut down into and incorporate some of the net-textured mineralization at its base forming a massive sulphide layer.

Subsequent deformation, after the formation of the nickel ore bodies, can have a variety of effects and modify primary magmatic textures in a variety of ways. In the Thompson nickel camp of northern Manitoba many of the better orebodies have been remobilized into regional fold noses and have steeply plunging morphologies more similar to Archean gold deposits than classic nickel sulphide deposits.

Sorry this is a bit longwinded, but it is a good reference as the Cathedrals Belt and the remaining prospects reveal themselves as potential deposits.

Cheers all
Helmenesh.