中文摘要：

理解大陆板内玄武岩的源区组成和成因是认识地幔动力学过程和化学不均一性的重要途径。由于不同地幔端员具有不同的水含量及水与其它不相容元素的比值（如H2O/Ce）,原始水含量的测定对于认识玄武岩的源区组成将会提供新的信息。玄武岩玻璃和斑晶中的熔体包裹体是获得海洋玄武岩原始水含量的主要样品,但是不适合于大陆玄武岩,因为大陆玄武岩玻璃由于强烈的去气作用不能反映真实水含量,而大陆玄武岩斑晶中的熔体包裹体少而小,不易获得足量、准确的数据。本文介绍一种最近发展起来的推断大陆玄武岩原始水含量的方法,即利用红外光谱测定玄武岩中单斜辉石斑晶的水含量,然后结合水在单斜辉石与玄武质熔体中的分配系数来反演与斑晶平衡的熔体水含量,进而估计原始玄武质岩浆的水含量。文中详细叙述了方法的适用性、误差的估计以及具体的操作流程,并通过东北双辽和华北太行山新生代玄武岩的研究实例,展示了玄武岩水含量对于源区组成的有力制约。

英文摘要：

Source components and genesis of continental intraplate basalts are pivotal to understanding the chemical heterogeneities and geodynamic processes of the Earth＇s mantle. Since different mantle end members have different H2 O values and H2 O / incompatible element（ such as H2 O / Ce） ratios, the H2 O content of primary basaltic magma might provide constraints on source components of continental intraplate basalts. Quenched glasses and melt inclusions in phenocrysts are commonly used to obtain the water content of primary magma of oceanic basalts, but they cannot provide useful information concerning the water content of primary magma for continental basalts. On the one hand, continental basaltic glasses usually experienced highly degassing when they were erupted at the surface due to the lack of water pressure to oceanic basalts, thus causing underestimation of the true water content. On the other hand, melt inclusions in phenocrysts in continental basalts are rare and verytiny（ 20 μm）, which hinders accurate analysis of large quantities of samples. This paper introduces a newly developed method for estimating the water content of primary magma of continental basalts. The H2 O values of clinopyroxene phenocrysts in basalts are determined by FTIR, and those of equilibrated melts are calculated through partition coefficients of H2 O between clinopyroxene and basaltic melt. When the effects from degassing, assimilation and fractional crystallization during magma ascent are evaluated, the H2 O content of primary magma of continental basalts can be estimated. The feasibility of the method, the evaluation of the uncertainty and the detailed operation procedure have been described. With this method, the H2 O content of the Cenozoic alkali basalts from Shuangliao of Northeast China and Taihang Mountain of NCC have been estimated. Combined with other geochemical index,these new data provide additional information on the source components of basalts.