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K_(60)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K_(60)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。
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 overthickened 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 K60 value 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.
出处
《地质论评》
CAS
CSCD
北大核心
2007年第2期198-206,I0008,共10页
Geological Review
基金
国家自然科学基金(编号40572128
40376013
40104003)的成果。
关键词
钾质火成岩
成岩过程
火成岩组合
K60值
地球化学判别图解
potassic igneous rocks
petrogenetic process
K60 value of igneous rock association
geochemical discrimination diagrams
作者简介
汪洋，男，1969年生。1991年毕业于中国地质大学（北京）。主要从事岩石学研究。通讯地址：100083，北京市海淀区中国地质大学地球科学与资源学院；Email：allen_thalassa@sina.com。
