LOW-TEMPERATURE HYDROTHERMAL VEINS WITHIN DEPOSITS OF THE BANDED IRON-ORE FORMATION OF KOLA PENINSULA

摘要

Last years, the list of hydrothermal minerals revealed in rocks of banded iron-ore formation, within Olenegorsky region ore-fields, has been added with those minerals: stilbite-Ca, heulandite-Ca, chabazite-Ca, laumontite, fluorapophyllite, datolite, thaumasite, pumpellyite-Mg, kainosite-(Y) etc, meant untypical for Archean complexes. In somecases, all they occur as rather large segregations, quite comparable with similar aggregates in Sarbaiskoye and Dashkesanskoye iron-ore deposits, without showing any connection with later geologic events. Datings of titanite from horblende-meionite nodules (2.65 G. a.) and diopside from its veinlets in the banded iron-ore formation (2.5 G. a.), geological position of these rocks (all the low-temperature assemblages arc located, without exception, within the minable ore zone) show their origin linked with the Archean iron-ore-forming processes. Association of the same minerals with the same composition was detected also in microinclusions within the native gold extracted as by-product of the Olenegorsky deposit iron ore processing. From this point, the hydrothermal mineral assemblage appears worthy to be studied too.