K-RICH AND NA-RICH GLASSES IN MANTLE XENOLITHS FROM YITONG, JILIN PROVINCE, CHINA - EVIDENCE FOR UPPER-MANTLE FLUIDS

Glasses are often found in mantle-derived peridotite xenoliths. It is usually considered that they are formed by the decompression melts of pre-existing minerals in the mantle xenoliths during their rapid trans port to the earth surface[1,2]. We have found K- and N-arich glasses i n mantle xenoliths from Yitong volcanic swarm, Jilin Province, China. Our study has shown that they are neither the product of decompression melting nor the product of basaltic magma. We believe that they come from the upper mantle fluids.