Conditions of formation of the Pavlik gold-sulfide-quartz deposit (North-East of Russia), according to the fluid inclusions study

Abstract

The stockwork gold-sulphide-quartz ores of the Pavlik deposit (North-East of Russia) are formed mainly by homogeneous, low saline (9.4—4.3 wt. % eq. NaCl), essentially water-chloride fluid at temperatures of 275о–330оC and a fluid pressure of 600—1840 bar. The fluid is characterized by a sufficiently high CO2 and a reduced methane content – the ratio of CO2 / CH4 = 17—37.3. In the fluid, among the cations, the main role is played by: Na and Ca, and K and Mg are in a subordinate amount. In addition, many trace elements were detected in the fluid composition: As, Li, Rb, Cs, Mo, Ag, Sb, Cu, Zn, Cd, Pb, U, Ga, Ge, Ti, Mn, Fe, Co, Ni, V, Cr, Y, Zr, Sn, Ba, W, Au, Hg and REE. The obtained data allow us to assume a decrease in the depth of ore formation during the formation of the deposit by 4—5 km due to the rise of the ore-bearing block. Attention is drawn to the low fluid pressures for a number of samples (330—140 bar), which may be associated with a separate stage of mineral formation. The ore-forming fluid of the Pavlik deposit in composition, temperatures and pressures shows similarities with the fluids of the neighboring Natalka and Rodionovsky deposits and has a great similarity with typical fluids of orogenic gold deposits. The information given in the article is of great practical importance for regional predictive metallogenic constructions, prospecting and evaluation of gold deposits.