If I may contribute to your conversation.
Ditto. :-)
I suggested on the WSP thread some time ago that the east/west trending fault running the width of Snap Lake may in fact have been the conduit or part of the conduit by which the kimberlite came to the surface. However, why the kimberlite flared laterally in multiple directions into more resistive rock, rather than simply following the falling resistance of the fault right to the surface is a question that I have not yet heard a satisfactory theory address.
Nor, from my perspective at least, have I.
In addition, to the best of my knowledge, no NWT kimberlites have been age dated older than 110 my (5034) and most are much much younger. If they were as old as 2.2by they would most certainly be heavily eroded (and older than any yet dated anywhere in the world).
I have not heard of any 500 MY old kimberlites either. Most of the ones in the Lac de Gras area are *about* 60 million years old.
I recall that Snap Lake is considerably older, and, going purely from memory, I think 150 MY was close to the estimate.
Regardless, a number of learned men suggest that the Snap Lake dike is an anomaly. That is to say that it may not be a pipe root zone and therefore not heavily eroded.
Anomaly is the key word. Nobody knows what it is, at this stage.
If that is true, continuity of width at depth may be problematic as typically, uneroded near surface emplacements typically pinch off substantially with depth. That is of course why pipes have a carrot shape.
True. However, the thickness data seems not to support that, at least yet. Again, the unknown anomaly...
As regards grade increasing at depth, is this proven or a statistical supposition by you or another poster?
Hmmm. Well, it was not me. See below, however.
Again, the norm is for grade to decrease at depth along with the degree of diamond reabsorb ion. For it to increase, one wonders if there might not have been multiple emplacement events some of which failed to make the surface.
One can wonder many things, but one seems to always come up short of a definite answer.
Part of the problem here is the fact that the grade *does* improve with depth, over the better drilled portions above 500 metres. That trend does not appear to continue, but neither can it be said that the grade drops off with greater depth at this juncture.
Keeping in mind that kimberlites only gain their diamonds by scouring them from their peridotitic hosts, you can appreciate that once the initial explosive penetration had scoured available diamonds, subsequent passing kimberlite magma should not logically find such rich ground to harvest in its passage.
One of my initial thoughts, but one that was rained on by the likes of Blusson, Jennings, et. al. Subsequent passing kimberlite need only enlarge the passage to scour more.
However, again, Snap Lake is appearing more and more to be an anomaly and if for example it has sustained multiple intrusive events, they might also have intruded through multiple weak points in the craton.
Yes, that too. Nevertheless, the company stated on many occasion that all evidence suggested a single emplacement.
Considering all of the above, and especially the possibility of multiple events hence multiple even parallel dikes, there is ample room for any eventuality in the case of that kimberlite deposit.
Yes, and that pretty well says it all.
Good luck to all shareholders and especially SUF's in CJ's efforts to find a feeder extension.
I'm sure he will appreciate the thought.
Regards,
WillP |
