Gold mineralization of the interformational contact of Riphean and Devonian deposits (Tsilema uplift, Middle Timan)

The article presents the results of studying native gold and the mineral composition of the heavy fraction of samples from the zone of interformational contact of the Middle Devonian and Middle Riphean deposits, opened by a ditch in the upper reaches of the Volchiy Creek (a tributary of the Tsilma River). Titanium and rare earth minerals predominate in the heavy fraction. Native gold is small (0.25-1.0 mm), with an ore appearance, a low degree of roundness and various forms. The Ag content in gold is up to 10.3 wt. %. Fineness is 899-1000 ‰. The internal structure of gold is heterogeneous and is characterized by a granular, block-mosaic structure. Inclusions of pyrrhotite, pyrite, galena and arsenopyrite are found in gold. The inclusion of pyrite in gold is similar in composition to the inclusion of pyrite in quartz. Gold is noted in intergrowths with quartz, less often muscovite. For the first time, gold intergrowth with rutile was found in the Middle Timan. Rutile has admixtures of V, Nb, and Fe. It is assumed that the primary sources of the studied gold are the zones of development of gold-quartz-sulfide disseminated mineralization, localized in the Riphean shale strata and intersecting quartz veins. The nature of the deposits, their mineral composition, morphology, and composition of gold of the studied interformational contact are similar to the complex diamond-gold-rare earth-rare metal-titanium paleoplacer Ichet'yu, which allows predicting the presence of similar ore objects not only within the Tsilema uplift, but also throughout Timan.