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将元素分析仪(EA)与气体质谱仪(MS)连接起来,能够进行硅酸盐岩石微量碳的含量和同位素比值测定。本文介绍了笔者建立这一EA—MS连线技术对天然岩石样品进行分析的方法原理及其对若干标准样品的分析结果。应用这一新方法,笔者首次测定了玄武岩、砂页岩和榴辉岩中全碳的含量和同位素组成,结果发现这些岩石普遍含有较高的轻碳(δ~(13)C=-20‰～-30‰)。皖东玄武岩的δ~(13)C值与碳含量呈正相关变化,指示其岩浆源区含有地表有机碳,岩浆喷发过程中经历过CO_2去气效应。巢湖砂页岩的低δ~(13)C值说明其中富含有机碳。东海榴辉岩的低δ~(13)C值指示,其玄武质原岩曾出露过地表,受到富含有机碳热液的蚀变。因此,岩石碳含量和同位素比值的EA—MS连线同时测定不仅为研究各种岩石的成因和地球化学历史提供了重要信息,而且对探索地球内部与表层之间碳的地球动力学循环提供了制约。
The elemental analyzer (EA) is connected to a gas mass spectrometer (MS) to determine the trace carbon content and the isotopic ratio of silicate rocks. This article describes the author of this EA-MS connection technology for the analysis of natural rock samples method principle and analysis of a number of standard samples. Applying this new method, the author first determined the contents and isotopic composition of total carbon in basaltic rocks, sand shale and eclogites, and found that these rocks generally contain relatively high levels of light carbon (δ ~ (13) C = -20 ‰ ~ -30 ‰). The δ 13 C values of the East Anhui basalts positively correlated with the carbon content, indicating that their magmatic source areas contained surface organic carbon, which experienced CO2 degassing during the eruption. The low δ ~ (13) C value of Chaohu sand shale shows that it is rich in organic carbon. The low δ ~ (13) C values of the East China Sea eclogites indicate that the basaltic rocks had been exposed to the earth’s surface and were altered by the enrichment of organic carbon hydrothermal fluids. Therefore, the simultaneous determination of rock carbon content and isotope ratios by EA-MS not only provides important information for studying the genesis and geochemical history of various rocks, but also provides an insight into exploring the geodynamic cycles of carbon between the Earth’s interior and the surface Restrictions.