Hello Teevee
If I may contribute to your conversation.
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.
Such faults are typically Archean in age in that area and can be deep seated, although most scientists do not believe that they extend to the Moho where kimberlites would be expected to first penetrate a craton. The diabase dikes being age dated to 2.2by is news to me. I believe there have been two major diabase dike events dated on the craton and to the best of my knowledge, neither is anywhere near that old.
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).
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.
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.
As regards grade increasing at depth, is this proven or a statistical supposition by you or another poster?
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.
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.
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.
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.
Good luck to all shareholders and especially SUF's in CJ's efforts to find a feeder extension.
Regards |
