中国东部地幔CO_2流体包裹体的碳同位素初步研究

PRELIMINARY STUDY OF CARBON ISOTOPE IN MANTLE CO_2 FLUID INCLUSION FROM EASTERN CHINA

采用分步加热爆裂法收集中国东部１１个地点的新生代玄武岩中１３个富ＣＯ２流体包裹体捕虏体（包括１２个橄榄岩和１个麻粒岩）的ＣＯ２，做了碳同位素测定，８００℃的δ１３Ｃ主要集中分布于－１６．０‰－－２２．０‰，１１００℃的／δ１３Ｃ主要集中分布于－２１．０‰－－２９．０‰。初步结果表明，地幔演化不同阶段的流体ＣＯ２碳同位素组成不同。

CO2 in xenoliths of CO2-rich fluid inclusions(including twelve peridotites and one granulite)in Cenozoic basalt from eleven regions of eastern China has been extracted using method of explosion through step heating, and its carbon isotopes have been determined.The resuIts show thatδ13C at 800℃ mainly ranges from-16.0‰to-220‰, while that at 1100℃ from-21.0‰t0-29.0‰. There exist lowδ13C and inhomogeneity of carbon isotopic composition in mantle fluid from eastern China, and high temperature carbon has an even lower δ13C, No significant correlation has been shown between carbon and oxygen isotopes.