Hi chuck,
In responce to your question, there is little data to go on, so I can't be sure, however, the intersection at 150 meters deeper than anticipated suggests either that:
1. there is a fault off set, or
2. As you approach the apex/feeder of the cone (pipe perhaps?) the dip of the cone sheet will quickly steepen. I have previously estimated the depth to the apex/feeder to be about 700-800 meters.
Regarding the alteration in the hangingwall versus none in the footwall: I don't have enough data to speculate.
On other items: the breccias that occur within the cone sheet. My preliminary thoughts are that they occur in portions of the cone sheet, where there was scaling or spalling of the footwall and or hanging wall, during injection of the kimberlite magma, at or near where the breccias are located. A high degree of roundness to the clasts would indicate that they were entrained in the magma and milled during the injection process.
My preliminary thoughts on underground mining is that there should be slight serpentinization of the kimberlite at the footwall and hanging wall contacts-the implication being that the "ore" would break cleanly with little to no dilution. In general, Slave Craton granites should make very sound roof rock.
regards,
teevee |
