Preliminary petrographic observation and microthermometric measurements show that there exist three types of fluid inclusions in quartz veins and late stage carbonate veins in HP-UHP rocks from CCSD, including brine (NaCl - H2O) inclusions ( type I), NaCl-CaCl2 - H2O system inclusions (type II) and N-2 - CH, pure gaseous inclusions ( type III), among which the type I may be divided into medium-high salinity (type Ia), medium salinity (type Ib) and low salinity (type le) brine inclusions. The type III are firstly discovered in the CCSD. Type Ia, Ib and II inclusions mainly occur as primary or pseudosecondary ones in vein- or matrix quartz in the eclogites, while they were not discovered in vein- or matrix quartz and in the amphibolite facies gneisses, suggesting that these inclusions were probably captured in decompression-recrystallization and retrograde metamorphism of the eclogites. On the contrary, type le inclusions are widely distributed and were probably captured in the last stage of UHP exhumation. N-2 - CH4 pure gaseous inclusions are mostly primary ones and mainly occur as isolated or clustered inclusions in laminated quartz veins in the eclogites together with la and III inclusions, implying that the type III inclusions were probably captured in HP-UHP metamorphism. Most of the quartz veins in the eclogites were probably formed by decompression-recrystallization and retrograde metamorphism during exhumation of the subducted plate, while the quartz veins in the gneisses were mainly formed by amphibolite facies or late stage retrograde metamorphism during the exhumation. Distinct differences in compositions and geochemical characteristics of the fluid inclusions in the quartz veins in the eclogites and those in the gneisses, and similarities of the inclusions in the quartz veins and the matrix quartz crystals in their respective hosting rocks suggest that the metamorphic fluid expelled from exhumation of the HP-UHP rocks in CCSD during the exhumation flowed mainly at grain scale.
