Abstract:

Abstract:  More and more field observations and experimental data show that gas plays a certain role in the transport and enrichment of mineralizing elements. Sublimates and condensates formed from high temperature volcanic gases are enriched with various magmatic components and oreforming metals. Mineralizing elements are also detected in moderate to low temperature water vapor occurring in geothermal field. The vaporrich fluid inclusions are enriched in Cu and Au even more than the coexisting brine inclusions in some porphyry coppergold deposits. The theoretical assumption of gaseous transport of metals as simple chlorides, fluorides, sulfides, oxyacids and atoms underestimates the capacity of the gas phase to transport metals below 400 ℃, hence the solvation or hydration should be taken into account , which is demonstrated by the solubility experiments of silver, gold, copper, tin, molybdenum and tungsten in hydrothermal vapors. Thermodynamic modeling based on the experimental data indicates that hydrothermal vapors can transport sufficient metals to form economic epithermal and porphyry deposits. In addition, experiments show that the partitioning of arsenic and boron into vapor phase from liquid is also related to the hydration, and the vapourliquid distribution coefficients increase with temperature and vapor pressure. Undoubtedly, the theory of oreforming metal transported in hydrothermal vapor is significant to the understanding of the forming mechanism of metal deposit and the development of the geogas prospecting methods such as deeppenetrating geochemistry.

Key words:

Key words: ore-forming metals; gaseous transport; solubility; experiments