Southern Urals and Rudny Altai: A Comparative Paleovolcanic and Metallogenic Analysis

Аннотация

The authors have performed a comparative paleovolcanic and metallogenic analysis of two massive sulfide-bearing regions: the Southern Urals and Rudny Altai, which are located in different parts of the Ural-Mongolian fold belt. Comparison of the geodynamic evolution of these areas, the formation and facies composition of the ore-hosting strata and types of massive sulfide deposits has made it possible to conclude that the regions are similar only in the most general terms. Fundamental differences in the structure and composition of the Earth’s crust in these regions resulted in differences in the profile of island-arc magmatism: basaltoid in the Southern Urals and rhyolitoid in Rudny Altai. This in turn determined the predominant composition of massive sulfide mineralization: copper-zinc in the former region and polymetallic in the latter. They are also characterized by opposite trends in the evolution of volcanism: homodromous in the Southern Urals and antidromous in Rudny Altai, which resulted in different positions of the types of massive sulfide deposits in the strata of ore districts: from bottom to top, copper-massive sulfide deposits are replaced by polymetallic deposits in the Southern Urals, and barite-polymetallic deposits, by massive sulfide-polymetallic and copper-massive sulfide deposits in Rudny Altai. There are also substantial differences in the regularities of lateral ore localization: more starkly manifested control of mineralization by central-type paleovolcanic edifices in the Southern Urals and the frequent position of mineralization in intermediate and remote volcanic facies in Rudny Altai, which is expressed in the predominance of volcanic rock in Ural ore-bearing sequences and a significantly larger fraction of relict rocks (20–80%) in strata hosting mineralization in Rudny Altai.