FAHLORES IN PALEOZOIC VENT CHIMNEYS FROM THE URALS AND RUDNY ALTAI VOLCANOGENIC MASSIVE SULFIDE DEPOSITS

Abstract

Tennantite, tetrahedrite-tennantite, tetrahedrite and their Ag-, Bi-, Hg-, and Te-containing fahlore varieties including pure end-member of goldfieldite occur in mid-temperature galena-sphalerite, quartz-marcasite and quartz-chalcopyrite zones of vent chimneys from the Urals (Yubileynoye, Yaman-Kasy, Valentorskoye, Molodezhnoye, Oktyabrskoye, Uzelga-1, Uzelga-4, and Alexandrinskoye) and Rudny Altai (Artemyevskoye, Nikolaevskoye, Zarechenskoye) Paleozoic volcanogenic massive sulphide deposits. The composition of fahlores decrease in Fe/(Fe+Zn) and, commonly, in As/(As+Sb)) while portion of acid volcanic rocks is expanded in relation to basalts or black shales in the range from Cu-Zn to Pb-Zn-Ba-Cu volcanogenic massive sulfide deposits. In this range, the consistent pertain is interpreted in terms of increasing in pH and state of solution oxidation due to most efficient seawater interaction with hydrothermal fluid and acid volcanic host rocks. The dependence of fahlores composition from host rock composition (basalts or sediments) and maturity of the hydrothermal systems are verified by physical-chemical simulation.

Keywords

• fahlores
• paleozoic black smokers
• ural
• rudny altai
• volcanogenic massive sulphide deposits