Abstract:

According to the traditional mineral deposit geological data, skarn is only formed from intermediate-acid magma contacting and replacing carbonate, but skarn original rocks are not pure carbonates and their compositions of some skarn original rocks are close to those of skarn in recent studies, so the traditional genesis of skarn deposit would be further investigated. Xiekeng Cu-Au deposit, Xunhua County, Qinghai Province, which was found in 1990's, is a garnet-skarn-type and garnet-diopside-skarn-type deposit. Petrochemical characteristics and geochemical characteristics of rare earth elements and trace elements of the mineralized skarn are rather similar to those of the marlitic-sedimentary and pyroxene-diorite-type magmatic rocks, therefore, this kind of skarn is not the traditional skarn but the skarn which is formed by auto-metamorphism of magmatic rock and marliticsedimentary in the hydrothermal process by systematically studying on the geochemical characteristics of the skarn.

Key words: genesis of skarn, petrological geochemistry, genesis of auto-metamorphism, Xiekeng Cu-Au deposit, Qinghai Province