【摘要】 本文探讨当前中国东部中生代钾质火成岩研究中存在的几个问题,即:“C型埃达克岩”的成因、无负Eu异常粗面岩—正长岩的成因、火成岩组合的K₆₀值推算造山带地壳厚度的可信度,和玄武岩构造环境判别图解对中国东部中生代钾质基性岩的适用性。本文认为:①中国东部中生代“C型埃达克岩”有多种成岩过程,并非仅仅源于下地壳物质的部分熔融。②加厚下地壳部分熔融不能形成无负Eu异常的粗面岩—正长岩,同时“C型埃达克岩”与玄武质岩石高压条件下部分熔融产物在钾含量方面具有显著的差别。③火成岩组合的K₆₀值不能用于估算中国东部中生代造山带地壳厚度。④一些常用的玄武岩构造环境地球化学判别图解并不适用于中国东部中生代钾质基性岩。更多还原

【Abstract】 This paper briefly discusses some problems in current research on the Mesozoic potassic igneous rocks in eastern China,i.e.the petrogenesis of“C-type adakite”,the petrogenesis of the trachyte or syenite with no negative Eu anomaly,the reliability of the crustal thickness derived from the K₆₀ value of igneous rock association,and the applicability of geochemical discrimination diagrams for basalts when applied to the Mesozoic potassic mafic rocks in eastern China.The following conclusions are proposed:（1）the“C-type adakite”can be generated by multiple petrogenetic processes besides the melting of over-thickened lower crust;（2）the trachyte or syenite with no negative Eu anomaly cannot be generated by the melting of over- thickened lower crust;meanwhile,the compositions of“C-type adakite”are distinct difference between the products from high-pressure partial melting of basaltic rocks in potassium content;（3）the K₆₀value of igneous rock association cannot be used to estimate the crustal thickness of the Mesozoic orogenic belts of eastern China;and （4）some common used geochemical discrimination diagrams for basalts is not suitable for the Mesozoic potassic mafic rocks in eastern China.更多还原