Magnesite mineralization in wall rocks of Salianovskoe massive copper sulfide ore deposit (the Middle Urals)

Soroka E. I., Pritchm M. E., Lyutoev V. P., Galakhova O. L.

Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2016. V. 145. N 3. P. 23-36

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Language: Russian

Abstract

Studied carbonate mineralization in host rocks of the Safianovskoe massive copper sulfide ore deposit is represented by transitional varieties of magnesite forming in solid solution series with siderite and dolomite. There are four types of magnesite mineralization distinguished by contents of Fe, Mg and morphological features. First and second types are represented by scattered dissemination and thin veinlets of ferruginous magnesite; the third type — by dolomite-magnesite veins filling rupture and shear fractures. Siderite-magnesite veins at the contact with sphalerite-pyrite ores belong to the fourth type. EPR (electron paramagnetic resonance) spectra of third and fourth types magnesite do not show lines of Mn²⁺ ions, which means the low concentration of manganese in the mineral lattice. It seems that the high Fe²⁺ content in magnesite is blocking the manganese participation in the lattice. In the whole, obtained data indicate the close connection of magnesite mineralization with ore-forming solutions. According to the isotope analysis data on vein-shaped carbonates, the fluid was enriched in light isotopes of carbon (δ¹³C_CO₂ -5.9 - ÷ -6.3 ‰) and oxygen (δ¹⁸O_H₂_O 6.6-12.9 ‰). Contrast variations of the fluid isotope composition might be provided by a mixture of fluids from different sources.

Key words: Fe-rich magnesite, siderite, dolomite, ore-bearing rocks, ERP spectra, isotopy of carbon and oxygen, Safiyanovskoe deposit.