Igneous bodies in the Wanikande-Wanakom area include dioritic rocks, micrograbbros, nepheline syenites, dolerites, basaltic sills, nephelinites
, trachytes, and pyroclastics.
Subduction then stopped, preserving the diamonds which had formed, and later these were transported to the surface by non-kimberlitic magmas such as leucitite, melilitite, nephelinite
, and basanite--"diamonds have been found in several diatremes and dikes with these compositions in eastern Australia" (Barron et al.
Carrier rocks are postulated to be nephelinite
, basanite and leucitite.
Occurrence: In upper-mantle garnet-granulite xenoliths in olivine nephelinite
These finding are significant because it shows that these extremely bizarre lavas and their parent magmas, nephelinites
, were produced by melting of a typical upper mantle mineral assemblage without an extreme carbon content in the magma source," said geochemist Bernard Marty at the Centre de Recherches Petrographiques et Geochimiques in Nancy, France.