Geology Reference
In-Depth Information
(a)
(b)
Figure 6.12
Idealised section through a kimberlite pipe, showing proposed
facies and real examples: (a) A highly altered kimberlite breccia from Letseng
diamond mine, Lesotho, Africa. (b) Hypabyssal/dike example from Bellsbank,
South Africa (photo courtesy of Graham Pearson).
mica (phlogopite). These rocks may be named according to the scheme shown
in Figure 3.14 and are believed to represent samples of the upper mantle.
It has been suggested that there are key facies in kimberlite pipes (
Hypabyssal,
Diatreme, Crater
, for example, Figure 6.12), and indeed the nature and form of
kimberlites has in the past been driven by the earliest examples found which were
pipe like bodies. It should be noted, however, that more recent discoveries of kim-
berlites show a much more varied form of intrusive and extrusive varieties, and
careful mapping has shown that the different facies types can be mixed together
at different levels within a single kimberlite.
