RE: U/G geology maps ?Some relevant info from the ACA Howe report:
Within the bulk sample area anomalously high projected diamond contents have been obtained from within individual sampled intervals from the caustic fusion of the diamond drill holes and RC DMS concentrates. These zones are directly related to the recovery of macrodiamonds as it only takes the recovery of one significant stone in a sample to give an anomalously elevated projected carats/tonne value. A few of these zones are however related to the recovery of many macrodiamonds from one small sample interval and this does indicate the possibility that there may be real high-grade zones within the Star deposit. Macrodiamonds have been recovered from all the geological units found in the Star kimberlite. It is also noted that the same geological units that contain sampled intervals where many of the best stones have been recovered extend above and below the sampled sections and thus it is anticipated that similar stones will be recovered from larger bulk rock sampling. The geological zones where the largest macrodiamonds have been found to date do not appear to exhibit any special characteristics to suggest that they are unique. All the major eruptive and potentially reworked facies in the Star kimberlite have returned macrodiamonds. In hole Star 31RC the total diamond count and projected diamond content (based on greater than 50% recovery) stabilises below 180m and diamond contents (based on all diamonds including micros, and recovered dry tonnes) from almost all the intervals from 180m to 295m vary between 0.1 and 0.2 40 carats/tonne (Figure 7b). This less erratic diamond content variation does reflect the more homogenous geological units found generally below 180m and also the much improved competency of the kimberlite.
It is likely that grade differences will occur within the gross geology of the deposit; grades and stone size may well be expected to be more erratic within the graded pyroclastic airfall deposits which typically vary from very fined grained to coarser grained layers in centimetre and decimetre layering. Many of the kimberlite units found deeper in the diatreme are more massive and more homogenous in nature. It is also noted that of the two largest stones recovered in Star 31RC one occurred between approximately 132m and 138m in the finer banded pyroclastic airfall deposits and the other between 240m and 246m in the more homogenous coarser grained massive macrocrystic kimberlite layer. Although this RC hole recovered much more material than any of the diamond drill holes it is still only a very small sample, however it is encouraging that the projected sample diamond contents of this hole are much less erratic than those from diamond drill results.
I would add that the anomolous counts only seem to appear near the vent, if you look at the appendices that show macros by interval.