Hey Lanrus, I have a feeling they will drop L259 completely as they cannot justify spending more money on it although I agree that the expansive depression remains a geological puzzle.
They drilled L259 down to a maximum of 225 metres and found no in-situ pyroclastic kimberlite (PK) but only Calonda (ancient fossilised alluvials) and Karoo sediments (country rock). There was no outcropping kimberlite ever found at L259, just a thin layer of sedimentary reworked volcaniclastic kimberlite (SRVK) near the surface but it never extended deeper and no PK layer beneath it was ever found. The SRVK is likely to have been sourced from the surrounding kimberlites and transported there over time as the L259 depression is an excellent alluvial trap.
If there was a smaller kimberlite within the large depression, you would think that the gravity survey would have shown it up as a denser body within the low-density depression but there was no evidence of this.
Is there the chance that if they drilled even deeper they may possibly find the elusive PK and confirm that the L259 depression is a kimberlite crater?
Possibly, the gravity model sloped from 78-108 hectares at surface to just 30 hectares at a depth of 600 metres. However, drilling this deep would likely be an academic exercise as there is little chance of an economic return at such depths.
Could they alluvially mine the L259 depression economically just like Block 8?
Not likely IMO. The Calonda component is the layer that contains alluvial diamonds but it is heavily diluted by the Karoo sediments also present and these are barren of diamonds. Costs would also be much higher due to depth.
Which areas of Lulo would be the most prospective for the source kimberlite(s) IMO?
They found the 227 carat Type 2A on Block 28 (4 km upstream of Block 8). Also even further upstream at Block 46 (8 km upstream of Block 8), they found an 88 carat diamond. Therefore, I think the areas around and upstream of Block 46 are very prospective. There is also a cluster of kimberlites to the east of Block 46 that also look good. Tributaries potentially link this area to both Block 28 and Block 46 where the large 227 carat and 88 carat diamonds were found respectively.
This is my take on it and is also just conjecture.
LOM Price at posting:
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