Age, Conditions of Formation, and Fluid Composition of the Pervomaiskoe Molybdenum Deposit (Dzhidinskoe Ore Field, South-Western Transbaikalia, Russia)

Abstract

The article discusses the composition of studied ore-forming solutions and the P-T conditions of molybdenum mineralization in the Pervomaisky stockwork deposit which is situated within the Dzhidinsky ore field (South-Western Transbaikalia, Russia). New geochronological data of zircons from granites, muscovite, and molybdenite from the ore zones indicates the association of the granite formation and ore deposition processes which occurred 119–128 million years ago. Quartz-molybdenite veins of the Pervomaisky deposit were formed at the temperature of ≥314–186 °C with some boiling periods. Fluid inclusions in these veins have total salt concentration of 6.3–12.7 wt. % NaCl equivalent (eq. NaCl). The salt solution is composed of chlorides of Na, Ca, K, and Fe. The gas phase contains CO2, CH4, and N2. A series of elements were determined in fluid inclusions by laser ablation (LA)-ICP-MS: Li, Be, B, F, Na, Mg, Al, Cl, K, Ca, Mn, Fe, Cu, Zn, Nb, Mo, Ag, Sn, La, Ce, Ta, W, Au, Pb, Th, U. The Mo content reaches 559 ppm (average of 228 ± 190 ppm) in high-grade quartz-molybdenite veinlets, whereas Mo content is up to 212 ppm (average of 25 ± 29 ppm) in the low-grade veinlets. High-grade veinlets were formed by near-neutral solutions with a higher content of Mo, S, and F, while relatively low-grade veinlets were deposited from alkaline solutions. Our results demonstrate the pH of the solutions as one of the key factors for ore deposition.

Mining Activities and the Chemical Composition of R. Modonkul, Transbaikalia

“…The ores of the Dzhidinsky economic deposits are complex. This orefield includes Pervomaiskoye Mo, Kholtosonskoe W, and Inkurskoe W deposits [1,2]. Industrial ores of Pervomaiskoye deposit contains (%): 0.1-0.15 Mo; 0.018 BeO; 0.031 WO 3 ; 0.024 Cu; 0.038 Zn; 0.04 Pb.…”

“…This was followed by the formation of the stockwork of hubnerite-bearing veinlets in the Inkurskoe tungsten deposit. The latest stage of ore formation is represented by the quartzhubnerite veins of the Kholtosonskoe tungsten deposit [1,2].…”

“…Since 2008, pilot work has been carried out on the recycling of tailings, and a mini-factory has been built. The natural-technogenic system covers an area of more than 100 km 2 [4]. It includes the industrial Pervomaiskoye, Inkurskoe, Kholtosonskoe deposits, plants, tailings, mine waters from adits, a metal casting plant (Liteyshchik LLC), urban treatment facilities, and a motor transport area.…”