Greetings all,
The following post is rather long and deals with structural geology 101, I hope it explains the terms correctly so that you can visualize what is going on as described in the press release.
1."All holes have intersected kimberlite at expected depths except for one that tested the up-dip limit of the NW dyke"
Imagine that all the overburden has been striped away from the peninsula and that the outcrop exposed is perfectly smooth and flat.
The dyke would appear as a straight road. The direction of the road is the strike.(running NW or SE depending which direction you are looking)
If you started to remove the kimberlite you would soon notice that it is a seam of material which dips at 15 degrees to the northeast. That is the down dip direction.
Now in reality the outcrop is not smooth or flat it is probably like rolling hills. This has been covered with overburden. So imagine that you are at the spot where the trench was put in to test the kimberlite. You take a drill 50 meters to the northeast (down dip) and drill a hole through the dyke, then you step out another 100 meters down dip and test the dyke again. So far so good. Now you move the drill up strike 100 meters and drill a hole and hit the kimberlite at the expected depth. Now you move up dip (toward where the kimberlite would sub outcrop) and you drill a hole. With this hole there is alot of overburden and you are still in overburden when you are at the depth you should hit the kimberlite, you keep drilling and eventually hit rock but no kimberlite. So you drilled a hole to test the up dip extension of the dyke but the dyke wasnt there. Why because the outcrop itself has dropped off and the kimberlite and rock has been eroded away. You would then have to move the drill back down dip away and drill another hole to see where it is.
This is just one hypothetical example of how you could drill an
up dip hole to test the extension of the dyke and miss.
2. "No significant structural off-sets on the dyke have been encountered in the area tested;"
It really helps for structural geology if you can visual three dimensional models in your head or draw a picture.
Take a piece of paper and a pencil and we will draw a cross section of this. If you could draw a line across the structure, the peninsula, and part the earth vertically along this line then you would see the cross section. So the top of your piece of paper is up, the bottom down, the left hand side is sw and the right ne.
First lets draw the surface. start at the left going right. This is the surface of the land so draw in a couple boulders and sprigs of grass as you go NE (3/4 of way across page)then the land begins to dip down and you hit snap lake. The surface of snap is perfectly flat but the lands surface now becomes the lake bottom so draw in both and put in a couple fish or diamond willy.
Now go back to the left side of the page and below the surface draw in a line which marks the border between the rock and overburden.
Above this line is overburden and below it rock so mark the two accordingly.
Now about a third of the way in from the left mark the dyke. You would put in two parrallel lines (the dyke is 2.6 meters wide and it dips down 15 degrees towards to right so they across the page and under snap lake.
Now you have a rough cross section and geologists draw these all the time to scale. using a ruler or a little trigonometery you can calculate how far down the dyke would be at any point along the cross section.
So you plot where your drill is set up, do you calculations and you can predict where you would hit the dyke and at what depth.
Now imagine that you drilled a hole and you were suppose to hit the dyke at 105 meters but you didnt hit it untill 205 meters. Either your calculations are way off or you have discovered a major (significant) structural offset. Either the dyke radically changed its dip or a fault dropped the dyke.
So what they are saying is they didnt encounter any major faults or surprises in their calculations.
3. "drill results obtained are interpreted as indicating broad warps in the kimberlite surface."
Now in the cross section you drew the dyke was represented by two straight parrallel lines dipping at ecactly 15 degres. In reality the dyke would shallow a little or deepen a little and thicken or thin a little. so as you drill your holes you discover this and adjsut your cross section accordingly. So it appears these slight changes arent caused by anything significantly structually, you didnt encounter any faults etc so those changes are caused by "broad warps in the kimberlite"
It would be really nice geologically if one could just slice the earth open and record the cross sections accordingly. In reality you see bits of the surface and drill little holes in the ground, then from what you hit you try to intrepret what is going on. Sometimes things turn out as expected, sometimes you get some real surprises. This is why sometimes you have to drill alot of holes to really figuer out what is going on.
Just take the cross section for a minute (this is not snap but hypothetically a dyke you find in your back yard)and imagine this you decide to drill a fence of holes down dip (along the cross section)
Where the dyke suboutcrops under the overburden it is 4 meters wide and dips at 15 degrees. You step out 100 meters and drill a hole the dyke is now 5 meters wide and dips at 12 degrees. You step out another hundred meters and the dyke is 2 meters wide and dipping at 17 degrees. You go another hundred meters out, your holes are getting pretty long and the dyke is 1 meter and dipping 19 degrees. So do you risk another hundred meter step out. Is the dyke going to be steeper and narrower or flatter and wider. You can quess but you wont know untill you drill. It could be twenty feet thick and flat lying or it could be .5 meters wide and dipping at 25 degrees.
Now what is going to happen on the next cross section you do north or south of this.
From the drill holes one has to extrapolate or quess what is going on between them. You drill alot of holes take quesses aat what is going on and then calculate to see if it is an orebody or mineable. |
