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Gold/Mining/Energy : SOUTHERNERA (t.SUF) -- Ignore unavailable to you. Want to Upgrade?

To: VAUGHN who wrote (6158)	8/21/2000 12:56:30 AM
From: russet	Respond to of 7235

<<<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.>>> Never say "only",...because all you need to do to create diamonds is have a carbon source subjected to high enough temperatures and pressures. To think we have uncovered all the possibilities that this can occur is suggesting we are some kind of gods who know everything there is to know. Randy Turner sponsored an amazing diamond research (Break Away Session) event at the last Roundup in Vancouver,...several interesting papers were presented including one describing lightning used as a power source to explore the conductivity of the mantle to depths of several hundred kilometers. Blow me away if they didn't find something special about the characteristics of the Ekati and Diavik areas of the Superior Craton. Their probes in Snap Lake malfunctioned or we might have interesting details of that area. Probes placed a few kilometers outside these areas did not display similar readings which could imply that the mantle in those areas did not have characteristics which would be conducive to producing the excellent diamondiferous qualities of kimberlite pipes and fissures inside these areas. Of course, it could imply absolutely nothing at all (gggggggggggggg). Perhaps you should consult with Alan G. Jones of the Geological Survey of Canada, Ottawa, Ontario for details and current data.

To: VAUGHN who wrote (6158)	8/21/2000 3:53:02 AM
From: teevee	Respond to of 7235

Vaughn, 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). You may be right-I don't know. I was responding to a poster named isotoper on SW. He wrote: the "southern kimberlite field" in the Slave may be considerably older than Cretaceous or Tertiary. There is one reliable age date in the public domain from AK5034 (obviously from BEFORE DeBeers were involved!) of 538 Ma with a small uncertainty (+/- 2 Ma). This is Cambrian. Drybones Bay kimberlite near Yellowknife also has some public domain data, ~ 450 Ma (Ordovician), but the systematics are more complicated. Heard some gossip that TWG Torngat dikes also gave an age of ~500 Ma . . The one published age on Ekati-area pipes is ~ 49 Ma and Jericho is 172 Ma, so there's quite a range. regards, isotoper 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. There are 3 sets of dykes: the oldest is east-west at about 2150my (not 2200 as I had stated but close for memory); a second north-east set at about 2100 my and the MacKenzie set at aabout 1200 my. 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. Although less common (or at least not as frequently observed given their flat lying nature), low angle faults are known to occur in metasedimentary and gneissic terrains and in shield rocks. This fact is evidenced by the occurance of large and extensive diabase sills versus dykes. As regards grade increasing at depth, is this proven or a statistical supposition by you or another poster? If you read my post carefully, and perform the calculations and contouring, you will see that I do not agree with the statement that grade increases at depth. 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. agreed 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. When the hydrostatic pressure of the overlying country rock exceeds the pressure duringand post emplacement of the kimberlite, the fissure will pinch or close up again. As that depth is approached the sheet will progressively thin. As for pipes, they have a carrot shape because the magma is gas charged and hot. When the magma approaches the surface, the volume of the gas doubles as the distance is halved and when the ground water table is encountered, a phreatomagmatic explosion likely occurs. 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. Apart from the one magma theory based upon micro diamond counts and petrology, because the sheet spread out in a sub-horizontal fashion, most of the kimberlite above the verticle feeder fissure cooled rapidly and was all within a similar isotherm. 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. SUF discovered low angle dykes or sills to the east at Munn Lake. There are many other fault zones with a similar trend to the Snap lake fault in the southern kimberlite field. Are there other low angle faults beneath the surface we can't see? Are kimberlite sills (low angle to flat sheets)more common than we think? Perhaps they are not so anomalous-they may be more extensive than we thought. Its just that we can't see them as they occur at depth. 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. Will Purcell cited CJ as saying he would advocate a drill test in the South west corner of their MacKay-Back Lake claim block. Good luck to all shareholders and especially SUF's in CJ's efforts to find a feeder extension. Hear hear. regards, teevee

To: VAUGHN who wrote (6158)	8/21/2000 12:17:51 PM
From: WillP	Read Replies (3) \| Respond to of 7235

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