COPPER DEPOSITS OF THE URALS: TECTONIC SETTINGS AND GEOLOGICAL ASSOCIATIONS

The Urals form the geographic divide between Europe and Asia and represent one of the major metal producing regions of Russia. The geology and mineral endowment are dominated by the Paleozoic Uralide orogen, a major orogenic belt that formed during the assembly of Pangea at the site of collision between the East European and Siberian cratons and the Kazakh collage. Closure of the Urals paleo-ocean through subduction led to formation of oceanic arcs in the west through the Silurian to the Devonian and a continental arc on the Kazakh margin from Devonian to Carboniferous times. The Magnitogorsk and Tagil intraoceanic volcanic arcs host economically significant Cu-rich VMS deposits and sub-economic porphyry copper deposits. The Tagil arc hosts a number of Cu-Au-magnetite skarn deposits. These belts collectively contained a conservative estimate of 65 Mt (million metric tons) of copper in the VMS deposits alone. These oceanic arcs collided with the passive margin of the East European continent and an allocthon of Silurian arc rocks containing copper-zinc VMS deposits was thrust onto the passive margin of East Europe. The East Uralian zone comprises a complex, fault-bounded collage of early Paleozoic rift sequences, volcanic arcs, and intrusions and marks the continent-continent collision between the East European craton and its accreted arc assemblage and the Kazakh craton. The East Uralian zone is intruded by at least two syn to postaccretionary granitoid suites, one of which is spatially and genetically linked to arc-like porphyritic andesites that host porphyry copper occurrences estimated to contain ~9 Mt copper. The Trans-Uralian zone, east of the East Uralian zone, is partly underlain by rocks of the Kazakh continental margin. The Valerianovka continental magmatic arc, developed on the Kazakh continent, hosts poorly explored porphyry copper deposits, Cu-Au skarns and giant magnetite bodies. Similar magnetite bodies are known in the Magnitogorsk arc and the timing of all these deposits relates closely to the final continent-continent collision between the Kazakh collage (Altaids) and the Uralides. The Urals were exhumed and partially eroded during latest Paleozoic time. Deep weathering from the Mesozoic to the present formed a number of significant supergene enrichment zones on cupriferous sulphide deposits.