LITHIUM ORES OF STANKUVATKA AND POLOKHIVKA ORE FIELDS (UKRAINIAN SHIELD)

Abstract

New results of mineralogic-petrographical and ore-geochemical research on Li-pegmatites and host rocks of Stankuvatka and Polokhivka ore fields of western part of Inhul megablock of the Ukrainian Shield are presented. Petrographic characteristics of host rocks, such as granites, metapelites, metabasites and ultrabasites are described. Aplite-pegmatoid granites related to Li-pegmatites have been dated as 2026-2042 Ma by means of U-Pb isotopic analysis of monazites. Li-pegmatites were formed during two stages: 1) magmatic, when formation of oreless quartz-albite-microcline pegmatites happened; 2) hydothermal-metasomatic, when residual fluid rich in rare elements affects previously formed minerals; it is reflected in presence of several generations of Li-bearing and rock-forming minerals. Initial magma was peraluminous, depleted with mafic components, and with water deficit. Albite was a first mineral crystallized in researched pegmatites. Then albite+quartz were crystallized. Then at the end microcline+quartz were formed in the central part of pegmatite veins. Petalite and spodumene were formed at the final hydrothermal-metasomatic stage. Practical importance of ores with secondary mineralization mainly presented with petalite and spodumene has been defined. Petalite ore type of Polokhivka deposit and petalite-spodumene mixed ore type of Stankuvatka deposit have a crucial role. Microprobe chemical analysis of accessory mineralization presented with triphylite, montebrasite, and other Lithium phosphates has been carried out. These minerals were detected in pegmatites and in metasomatically altered host rocks. They can be reliable criteria during geological exploration of Lithium at other locations of Shpola-Tashlyk ore district.