LAMPROITES AND KIMBERLITES IN CHINA AND THE GENESIS OF DIAMOND DEPOSIT

It is known that the lamproites occur in the southeastern Guizhou Prov ince and in the Dahong Mountains area, Hubei Province; and many para-l amproite occurrences spread in the west half parr of the South China l andmass. The para-lamproite diatremes in Ningxiang County, Hunan Provi nce, contain a few of fine grains of diamond. Parts of the kimberlite pipes and dykes in Mengyin County, Shandong Province, consist locally of basic kimberlite; and the kimberlite dykes in the Maping kimberlite area, Zhenyuan County, Guizhou Province, consist of basic kimberlite principally. Although the diamondiferous kimberlites and lamproites oc cur always in the cratons within continental plate, both the potassium -rich ultramafic rocks display the geochemical features of the magmati sm of post-collision in orogenic belt. Both the kimberlite and lamproi te magmas may originate from the local parts of the mantle transition zone, where the mantle contains the matter of ancestor slab of ancient subduction zone. And, both the K-rich ultramafic magmas generated in an active mantle plume, which came from the boundary between the core and the lower mantle. The basic kimberlite magma may be more capable o f preserving the crystals of the diamond type II.