Peregrine Diamonds Ltd. PGDIF

RE:coldest geotherm

[xDeBeers]

We look for diamonds where it is "old and cold". Hence Archean Cratons are ideal. Chidliak sits on the Superior (Archean) craton. It's usually shown as light pink on any standardised geological maps. A colleague of mine gave a presentation once aptly named "Superior by name. Superior by nature".
An Archean craton is geologically very stable. Thus there is less chance of the kimberlite having been sliced and diced, folded, faulted, metamorphosed etc.
Cold (geotherm) is good for more complex reasons, one of which is the kimberlite cools more quickly and thus the diamonds are more likely to be preserved.