Evidence for Primary Kimberlitic Liquids in Megacrysts from Kimberlites in Kentucky, U.S.A.

Inclusions within garnet and diopside megacrysts from kimberlite in eastern Kentucky contain Ti-rich phlogopite, serpentine, and calcite. The garnet inclusions also contain spinel, aluminous clinopyroxene, and chlorite. It is inferred that the inclusions in garnet were once the same as those in diopside, but spinel, aluminous clinopyroxene, and aluminous orthopyroxene (now serpentine + chlorite) formed at the expense of host garnet and included olivine. These polymineralic inclusions may represent included liquids of the same composition as the liquid from which the megacrysts crystallized, which may be a phlogopite-bearing kimberlite, unlike the kimberlite host rocks in Kentucky.