Re: Bedding planes?
in response to
by
posted on
Nov 30, 2009 06:58AM
San Gold Corporation - one of Canada's most exciting new exploration companies and gold producers.
Alright now, I know I'm a little late here but as a geologist, I feel I must comment on this.
A bed is a geology term used to describe a unit that is distinct from another unit, it can be two different rock types or the same rock type but just a change in grain size, colour or alteration. When geologist look at rocks, they look at the bedding planes, as those are the areas when a change occured, this is the contact, the area where one rock type changes to another. Usually this is used for sedimentary rocks where layers upon layers of sediment are stacked on top of each other, or for volcanic rocks where layers of ash and flows are stacked, in this case it refers to the vein in contact with the host rock.
Now for epithermal gold veins, these are late intrusions that came into an old system, the gold came in with quartz, as a liquid and shot through shears, fractures and weaknesses in the rock, it then hardened and here they are mining it now.
In diamond drilling, a geologist will do his best to try and plan his drill holes to intersect a vein or a target at a right angle, this way they get a better understanding of the true width of the vein. If you're drilling at a vein and hit it at..say a 20 degree angle to the core, you know you'll get a huge intersection as you cut the vein at this poor angle, but it's not a true representation of the width of thevein, it also doesn't really help the geologist or engineers when they want to plan to mine the thing. Sometimes though, especially when drilling underground you don't have the options to put your drill exactly where you want it so you drill from wherever you can. You'll note in press releases that "true widths are unknown" disclaimer is always out. Usually the geo has a pretty good idea just by looking at his core angle though.
Mr.Ginn here says the bedding plane is at a right angle in the core, this is a good sign, it means that it is most likely a close representation of the actual width of the vein.
Hope that helps