DISTRIBUTION AND FORMATION CONDITIONS OF W-MO ORE MINERALIZATION AT THE TYRNYAUZ DEPOSIT (RUSSIA)

General regularities in tungsten and molibdenum accumulation in the or e-forming process are discussed. Most W-Mo ores are associated with th e same hydrothermal feldspar-quartz metasomatic process. Skarns were p redominantly replaced by tungsten ores while hornfels were substituted by molibdenum ores. The main ore minerals are molibdoscheelite, schee lite and molibdenite. They were crystallized during the acid-leaching and deposition stages of the hydrothermal-metasomatic process. W-Mo or es show zonal distribution. From lower to upper levels (and more rarel y from the center to the borders of ore bodies): scheelite/molibdo-sch eelite ratio value and relative fraction of molibdenite increase and M o and W mineralizations separate in space. Some physicochemical condit ions of molibdoscheelite, scheelite, and molibdenite deposition and th eir assemblages were studied in dependence on ore metals and alkaline chlorides concentration, activity of sulfur and oxygen, acidity-alkali nity and temperature of ore-bearing solutions. Suggestions are based o n the structural, mineralogical, geochemical, experimental, and statis tical studies and on the comparative analysis of published and origina l data concerning the geology and geochemistry of W-Mo ore formation.