Title

N. M. Korolev, L. P. Nikitina, V. N. Zinchenko, J. Francisco

Eclogite xenoliths from diamondiferous kimberlite pipes Catoca and Cat-115, Kassai craton, West Africa. Mineralogy, formation conditions

The first data on the mineralogical composition, PT equilibrum conditions of mineral assemblages of eclogite xenoliths from the upper mantle beneath craton Kassai are represented in the paper. The types of eclogites, lowand high-MgO, the chemical composition of mineral and crystallization in a diamond phase are similar to eclogites in the mantle, underlying Man, Kaapvaal and Siberian cratons. Multi-stage evolution of the eclogites as a result of repeated changes in thermal regimes in the mantle beneath the craton Kassai captured in changing the composition of the rock-forming minerals and accessory rutile. Rutiles from the high-MgO eclogites contain Nb2O5 to 11.0 wt.% (ilmenorutile) exceeding the usual (up to 8.0 wt.%) content of Nb2O5 in rutiles of diamondiferous eclogite and forming inclusions in diamonds [6, 51]. Take into account for that Catoca kimberlite pipe is one of the richest diamond-bearing pipes of world, it is believed that the presence ilmenorutiles in kimberlites and their mantle xenoliths can be an important mineralogical sign of high productivity kimberlite on diamond.
Key words: craton Kassai, upper mantle, eclogites, termobarometry, high niobium retiles.