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Tominskoe and Miheevskoe are the first economic porphyry copper deposits discovered in the Chelyabinsk region of the southern Urals (Russia). The Tominskoe and Miheevskoe deposits have a total resource of about 3 million tonnes. The deposits are associated with island-arc related diorite intrusions which are widespread in the Urals but have been the subject of relatively little study. SHRIMP-II analyses of zircons from the diorite intrusion give U-Pb ages of 429-410 Ma. 87Sr/86Sr of the diorite is approximately 0.7049-0.7051 (429 million year) and (ΕNd)t is 6.7-7.5. Highly sericitized quartz diorite and intensely sericite-quartz-altered wallrocks have 87Sr/86Sr from 0.7041-0.7049, and values from 5.9-9.4. The ΣREE is very small (24-52 grammes/tonne), and there is no europium anomaly on spidergrams of REE compositions.
These facts are suggest a mixture of a basaltic magma derived from the lower crust-upper mantle with the ore-bearing granitoid. The ore zone stretches in a northwest direction for 12-15 km and has a width from 1.5 to 4 km. The dimensions of the ore-bearing intrusion are about 3.5 by 3 km. The intrusions and wallrocks have been altered to propylitic, sericite-quartz alteration assemblages. Mineralization occurs in all intrusions, but the core of the intrusive complex is impoverished In ore components. Sulphide mineralization is represented by pyrite, chalcopyrite, chalcocite, with rare molybdenite, pyrrhotite, bornite, sphalerite and tellurides. There are abundant copper-bearing residual soils. Given the discoveries of Tominskoe and Miheevskoe, the Urals have the potential to become the premier porphyry copper province of Russia.
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