RHENIUM MINERALISATION IN THE KURIL ISLANDS

Abstract

Rhenium is found in a great deal of occurrences in the Kuril Islands, apart from the known occurrence at the Kudryavyi volcano. Rhenium mineralisation is located both in the upper parts of the ore-magmatic systems with sublimation molybdenite-sulphur ores of the Quaternary volcanoes (≥n· 100g/t) and in the lower horizons of the Neogene volcano-tectonic structures (VTS) with epithermal gold-silver and (barite-massive sulfide)-complex ores (up to 25g/t). Distinctions between Re-bearing mineral assemblages of sublimation and epithermal ores of the Kuril occurrences are brought about by the gradient variations in the ore-forming system evolvement. Along with previously located ReS2 - MoS2 bisulfide at the Kudryavyi volcano, among carriers and concentrators of rhenium there were recognised Mo, Pb, Bi minerals in the Bilibin, Ebeko and Novyi volcanoes (up to 46400g/t Re), in the epithermal veins of the Prasolov volcano-tectonic structure (up to 37400g/t Re) as well as sphalerite, pyrite and fahlores, including those received through artificial precipitation from volcanic gases. The Kuril Re-Mo minerals are similar in composition to molybdenite, both in the high-rhenium porphyry-Co-Mo ores from the Kadjaran deposit (Armenia) and in the low-rhenium ores of the Yokoto-kuroko deposit (Japan). The correlation of rhenium with indium and cadmium in the ores of all studied Kuril occurrences is interpreted as an indicator of a possibility to recognise new Re-bearing minerals and mineral assemblages. The obtained data is an important prerequisite for discovering rhenium deposits in the Kuril island arc, and hence the study of regularities in formation and distribution of rare-metal ores in island-arc setting as well as a possibility of metal extraction from volcanic gases is a pressing question.