Место издания: Новосибирск , Год издания: 1992

The Eldorado deposit, representing a vein-veinlet type of gold-quartz formation, is localized in terrigenous-shale suite of the Middle Riphean Sukhopitskaya series (Yenisei Ridge). In the deposit there are three major varieties of quartz distinguished on the basis of fluid inclusions studies (thermometry, freezing experiments, and gas-chromatography). The first variety is the pre-ore milky-white quartz with numerous inclusions of liquid carbon-dioxide. The homogenization temperatures range from 300 to 570; temperatures of partial homogenization range from +1 to -22 degrees-C. The fluid pressure reaches 4 kbar. The second variety - ore quartz - contains also relict grains with inclusions of the first type (ca. 1% of all inclusions). The homogenization temperatures range from 210 to 490 degrees-C; and temperatures from partial homogenization - from -10 to +23 degrees-C. The fluid pressure reaches 2.2 kbar. The third variety, post-ore one, forms fine veinlets which often cut the first two types of quartz. The homogenization temperatures range from 100 to 120 degrees-C. No visible inclusions with liquid CO₂ were found. Quartz vein formed in multipli stages. Temperature, pressure, and fluid density all decreased with time, which reflects a regressive phase of regional metamorphism.