TWO GROUPS OF SYMPLECTITES FROM THE SAME KIMBERLITE PIPE

Abstract

Ilmenite-clinopyroxene intergrowths of graphic texture (symplectites) are interesting not so much because they are rare, but because they may shed light on the conditions of crystallization of the plutonic ilmenite-bearing mineral paragenesis. Until now, symplectites had been found only in three pipes in the Yakutian kimberlite province - the Mir, the Sytykanskaya and the Druzhba. And because of the great variability of the inclusions, only a few analyses of the composition of the clinopyroxenes from the Mir pipe have been published. The authors studied 13 symplectite inclusions from the Meri pipe (Kuoyka field), 1 from the Udachnaya-East pipe and 5 from the Mir. Most of the inclusions from the Meri pipe are intergrowths of ilmenite and pyroxene 2 to 5 mm in size, and only the straight contacts between the two minerals classify them reliably as symplectites. The presence of two groups of symplectites in the same pipe indicates that the kimberlite melt was originally a hybrid magma.