The results of studying the mineralogy of metamorphic schists from the Pre-Jurassic base of the Arctic part of the West Siberian plate are presented. The accessory and ore mineralization of schists from the Zapadno-Yarotinsky license area located in the southern part of the Yamal Peninsula is studied. The schists was uncovered by the Zapadno-Yarotinskaya No. 300 well at a depth of 2762 m. Above the section, the metamorphic rocks are overlain by a young Meso-Cenozoic cover. The schists are mainly composed of quartz, plagioclase (albite), carbonates (dolomite and siderite), mica (muscovite) and chlorite (donbassite). The discovered accessory and ore minerals in the metamorphic schists of the Zapadno-Yarotinsky area can be divided into two groups. The first group includes minerals that were formed during the metamorphism of schists, or were preserved as detrital matter. These minerals include zircon, fluorapatite, and rutile as the most stable compounds. The remaining mineralization (pyrite, sphalerite, chalcopyrite, cubanite, galena, cobaltite, barite, xenotime-(Y), goyazite, synchysite-(Nd), native silver and copper) is clearly secondary and was formed as a result of superimposed metasomatic processes. Judging from the described mineralogy, the schists underwent changes as a result of superimposed propyllitization. The temperature range of this process is determined by the formation of cubanite in association with chalcopyrite at a temperature of 200-210 оС.
The chemical and mineral composition of gabbroids of the pre-Jurassic basement of the Syunay-Salin area located in the Arctic part of the West Siberian megabasin on Yamal Peninsula is studied. Borehole 45 has drilled a layered gabbrodiorite intrusion, which was previously considered monotonic diorite one. The gabbroids are metamorphosed under conditions of the lower degree of the greenschist facies of metamorphism and also underwent propylitization, which is resulted in the formation of sulfdes including pyrite, chalcopyrite, also pyrrhotite, pentlandite, cubanite, samaniite and galena. According to mineral geothermometers, sulfde dissemination in Syunay-Salin gabbroids formed at temperature of ~200 °С.
