THE DUBRAVA MASSIF OF PYROXENITES, ALKALINE ROCKS, AND CARBONATITES

Abstract

The Dubrava massif, composed of pyroxenites, alkaline rocks, and carbonatites, was found in 1961 in northern Kazakhstan and is described for the first time in this paper. A geological map of the deposit was compiled taking into account the results of exploration drilling and magnetic survey on a scale of 1: 10 000. A petrographic description of rocks and their petrochemical characteristics are given. Magmatic carbonatites and metasomatic calcitic rocks are identified on the basis of ICP MS results. The carbonatites are characterized by subeconomic concentrations of Zr, Nb, Ta, and REE and very low U and Th contents. Carbonatites with a high P2O5 grade and metasomatic glimmerites with high contents of rare elements might become of economic interest in the future.