Abstract

The evolution of mineral-forming solutions in copper-molybdenum deposits of Kuznetsk Alatau, Eastern Transbaikalia, and Middle Asia is considered on the basis of the study of gas-liquid inclusions in minerals of different stages and mineral assemblages. The data permit estimation of the temperature, the state of aggregation, the composition, and the pressure of the solutions at various stages. K-feldspathization was caused by gaseous solutions at 730 degrees to 400 degrees C and pressures over 1,400 atm. Argillic and sericitic rocks formed from near-critical and liquid solutions at 430 degrees to 320 degrees C. Silicification took place in a wide temperature range between 800 degrees and 200 degrees C that varied in state of aggregation from gaseous to critical to liquid. The principal ore deposition occurred from liquid solutions enriched in carbon dioxide at 400 degrees to 200 degrees C. Essential differences can be shown in the chemical composition of the solutions forming various deposits. Solutions from deposits of Kuznetsk Alatau are essentially fluoride during the early stages and fluoride-carbonate rich at later stages. Those of Eastern Transbaikalia deposits are rich in chloride at early stages, chloride and carbonate at later stages. Those of Middle Asia deposits are rich in chloride.

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