中国东北地区中新生代岩浆岩中氮及其同位素组成  

Content and Isotopic Compositions of Nitrogen in Mesozoic and Cenozoic Magmatite Inclusions in Northeast China

作　　者：张成君[1] 陈发虎[1] 文启彬[2] 

机构地区：[1]兰州大学资源环境学院,730000 [2]中国科学院兰州地质研究所,730000

出　　处：《地质论评》2002年第1期24-28,共5页Geological Review

基　　金：国家自然科学基金(编号40041004);中国博士后科学基金;兰州大学博士留校科研启动基金

摘　　要：通过真空热解法分析中国东北地区中新生代以来形成的碱性玄武岩和基性侵入岩中氮含量及其同位素组成的差异,结果表明喷出岩和侵入岩中流体组分在岩浆的上升侵入过程中有不同的表现形式,喷出岩与围岩有较少的混染作用发生。碱性玄武岩包裹体中氮含量较低,为1.91～14.01μL/g,δ^(15)N为-22.6‰～-1.8‰。侵入岩包裹体中氮含量为25.39～731.30μL/g,δ^(15)N为+0.7‰～+20.9‰。碱性玄武岩中N_2含量和氮同位素组成可能部分代表了上地幔流体的特征,脱气作用造成同位素值有较大变化;而侵入岩中的N_2含量和氮同位素组成更多地反映了地壳中含氮物质浓度及同位素组成特征。Nitrogen content and its isotopic compositions in inclusions of basalts and basic intrusive rocks formed in Northeast China from Mesozoic to Cenozoic have been analysed by heating in vacuum. It is shown that liquid components of the extrusive and intrusive rocks have different behaviours in the process of intrusion, and only a little contamination has occurred between extrusive rocks and their country rocks. The content of nitrogen in alkali basalt inclusions is low, 1. 91 - 14. 01 μL/g, and δ15N is in the range of - 22. 6‰ to - 1. 8‰. The nitrogen content in intrusive rock inclusions is higher, 25. 39-731. 30 μL/g, and δ15N ranges from +0. 7‰ to + 20. 9‰. For alkali basalts, the nitrogen content and isotopic compositions may partly represent the characteristics of the upper mantle fluids, and degassing may cause the nitrogen isotopic ratios to change greatly. But for the intrusive rocks, the nitrogen content and isotope compositions better reflect the content and isotope compositions of nitrogen-bearing matter in the crust.

关 键 词：东北地区 碱性玄武岩 侵入岩 氮 同位素组成 脱气作用 中国 

分 类 号：P588.1[天文地球—岩石学] P534.6[天文地球—地质学]