6. Discussion and conclusions
Among lower-mantle minerals identified as inclusions in ‘superdeep’
diamond, can be distinguished three mineral associations juvenile ultramafic, ‘eclogitic’-type, and carbonatitic. The juvenile
(ultramafic) obviously predominates among them. The ‘eclogitic’-
type association is related only to subducted slabs which likely comprise
an insignificant volume of the deep Earth, and a carbonatitic
association, most likely, is associated with lower-mantle, carbon-rich
partial melts caused by carbonate-induced suppression of the liquidus
in the vicinity of thermochemical upwelling (Collerson et al., 2010). In
this case, the mineral and chemical composition of the lower mantle
can be approximated to the composition of the juvenile, ‘ultramafic’
association. However, it is important to point out that the mineral
frequency of the lower mantle minerals cannot readily be used as a
model for the overall mineral composition of the lower mantle