Carbon isotopes in eclogite and apatite separate from Huangzhen and Shima in SIE Dabie

The carbon isotope compositions of high- and ultrahigh-pressure eclogite an d apatite separate from Huangzhen and Shima in SE Dabie Mountains were anal yzed by EA-MS online technique. The delta C-13 values of the eclogites cove r a wide range of -30.7 parts per thousand - +1.5 parts per thousand, where as those of apatites only have a small range of -28.1 parts per thousand - -21.0 parts per thousand. Some of the eclogites with the high delta C-13 va lues suffered retrogressive alteration by CO2-bearing fluids. The low delta C-13 values of the apatites indicate that the eclogites contain surficial carbon of organic origin. It is concluded that protoliths of the eclogites were exposed to the surface of the Earth, and that the carbon-bearing fluid was depleted in C-13 during the eclogite-facies metamorphism.