Ireland8What do I think the source of the Ireland Twp magnetic anomaly is due to?? As the saying goes, it's anybody's guess!! With the exception of Lake Shore Gold's 2 drill holes over to the west, LA07-02 and LA07-03, there are no other sources of bedrock lithology to assist us in determining the source (rock types) for the large, circular magnetic anomaly.
First off, I would suggest that one should re-read my previous post (Ireland7 on Feb 15 2023), as it gives several of my thoughts on the property, and it means that I don't have to repeat what I've already said.
As there presumably are no outcrops on the property, we'll have to rely on geophysics and geochemistry.
The airborne magnetics shows a large near circular feature, indicating a few magnetic highs within an essential magnetic low. There are 2 'rings' around the outer perimeter and I find the inner of the two rings to be more interesting.
The VTEM airborne EM survey showed that there are no bedrock conductors, but it did show a flat lying conductor over the entire west side of the major north-south fault (Quinze Dam Fault) that runs through the middle of the magnetic anomaly. This area is an area of oxidation and could give us a clue as to what the source is at depth. But we don't have enough information on the oxidation zone, except where Lake Shore Gold intercepted it towards the west, in the hole LA07-03.
There has been no gravity surveying carried out over the anomaly, and if this was done, it may render another clue as to what may be at depth.
I still think that the major north-south fault is the Quinze Dam Fault, which is the eastern most fault within the Timiskaming Rift Valley, the latter being a graben. This structure is considered to be an important feature for potential ascending magma intrusives.
The quartz monzonite, in the two Lake Shore Gold's drill holes, caught my attention, especially with the extensive traces of chalcopyrite. Then I thought about the large Bingham Canyon and Bagdad copper mines!!
In Lake Shore Gold's DDH LA07-02, they logged 'blue quartz eyes'. At first I thought it might be riebeckite. It could still be. Then I thought of sodalite and corundum, as both of these are blue too. And they are generally associated with nepheline syenite, an alkaline intrusion.
So I started looking for nepheline syenite rare earth deposits in the literature and I found two that had sodalite in them, one is the Nechalacho nepheline syenite in the NWT (Vital Metals) and a second is the Lugiin Gol nepheline syenite pluton in Mongolia. Both are nowhere near Ireland Twp of course, but I found them interesting, for their shapes, as well as their comparable magnetic features to the Ireland magnetic anomaly. For the Lugiin Gol deposit, go to the following site:
https://www.mdpi.com/2075-163X/13/1/129#:~:text=The%20most%20prominent%20is%20the,Maihan%20Uul%20in%20Mongolian%20Altai.
The Lugiin Gol pluton also occurs in a graben associated with a prominent tectonic lineament in the Gobi-Tien Shan belt, just like the Ireland Twp magnetic anomaly is located within the Kapuskasing Rift Valley, with a major NS fault zone running through it.
The Nechalacho nepheline syenite also has a sodalite rim near the roof of the intrusive. Take a look at some of their maps. Their intrusion is layered too, as indicated in Figure 2.3.
https://ir.lib.uwo.ca/cgi/viewcontent.cgi?article=5847&context=etd
I don't think Ireland is either an IOCG or a carbonatite. Right now, my guessimate would be a nepheline syenite.
Because the Case Batholith has quartz monzonite in it, and because the two Lake Shore Gold's drill holes intercepted quartz monzonite, could this mean that the Ireland intrusive is a nepheline syenite contained within the Case Batholith??
There's no question that further exploration work has to be carried out on the property, before any drilling is done. Whether it be more soil sampling or gravity surveys, there needs to be more confidence in the targets that are being planned for drilling. A good place to start the soil sampling would be near the two soil samples, 28715 and 28728, where the best results from the previous limited program by Northern Shield Resources, were intercepted, especially rare earths. A sizeable grid around each, would be cost effective.
One question that I have is the 36 metres of 5% pyrrhotite in a porphyritic monzonite, that was intercepted in LA07-02 by Lake Shore Gold. Could this be considered a breccia zone and if so, what would be the significance of pyrrhotite in a geological environment such as this? Chalcopyrite could also occur as anhedral grains or as a poly- crystalline intergrowth associated with pyrrhotite They never assayed a section of it!!
Anyway, I hope the above will be of some assistance.