SULFIDE MINERALIZATION IN THE KURIL-ISLANDS - MINERAL PARAGENESES ANDGEOCHEMISTRY OF THE ENDOGENIC PROCESS

, The Kuril Islands, an island are, contain numerous young volcanoes, spatially associated with various ore occurrences and deposits of base and precious metals. The synthesis of the data on ore mineralogy and geochemistry for nine sites, situated on the island of Kunashir, Ituru p, Urup, and Paramushir, revealed three types of sulfide mineralizatio n: copper-zinc-massive sulfide, lead-zinc, and gold-silver-sulfide. Mi neral parageneses, with a similar composition and formation succession , were identified for each type; locally occurring specific associatio ns, which contain bornite and tellurides of silver and gold, were esta blished for the gold-silver-sulfide type. Variations of the chemical c omposition of pyrite, sphalerite, and galena were used as indicators o f definite mineralization types. The T-conditions (300-180 degrees C) in the formation of early and late mineral parageneses do not differ m uch in various mineralization types. A change in mineral parageneses i ndicates a change in pH-f(O2) conditions. The gold-silver-sulfide type was formed in an oxidizing environment. Fractionation of sulfur (delt a(34)S from -12.7 to +9.9 parts per thousand) and oxygen (delta(18)O f rom +2.8 to +13.9 parts per thousand) isotopes suggest that mineral-fo rming fluids of different origins were involved in ore magmatic system s.