Mineral association in pegmatites from the Djurkovo Pb-Zn deposit, Central Rhodopes: preliminary results

Deformed pegmatites of varying thickness and position are a significant constituent intruded in the metamorphic complex, hosting the Djurkovo Pb-Zn deposit in Central Rhodopes. The mineral composition of the pegmatites consists of plagioclase, K-feldspar, quartz, and minor micas. The main accessory minerals are allanite, titanite, apatite and zircon. Late hydrothermal alteration of pegmatites led to the formation of epidote, adularia, sericite, chlorite, carbonate, quartz and leucoxene. Rare earth carbonate-phosphate assemblage (REE+Y, Th, U), manifested as ˂ 20 µm anhedral grains, is observed along fractures and dissolved zones in allanite and titanite. Because of the limited mobility of REE in fluids, these elements are barely transported during the hydrothermal activity and are incorporated in new phases, precipitated in the frames of the altered accessory minerals. The studied pegmatites contain a significant amount of accessory minerals rich in incompatible elements and therefore could be considered as their potential source.