不同构造环境花岗岩类的Na2O和K2O含量变化特征  

Characteristics of Na2O and K2O content changes in different tectonic types granitoids

作　　者：刘凯 王瑞廷 任涛[1] 李剑斌 樊忠平 赵晓龙 赵亮 LIU Kai;WANG Ruiting;REN Tao;LI Jianbin;FAN Zhongping;ZHAO Xiaolong;ZHAO Liang(No.713 Party of Northwest Geoexploration Bureau for Nonferrous Metals,Shangluo 726000;Northwest Mining and Geological Exploration Bureau for Nonferrous Metals,Xi'an 710054;College of Earth Science and Land Resource,Chang'an University,Xi'an 710054)

机构地区：[1]商洛西北有色七一三总队有限公司,商洛726000 [2]西北有色地质勘查局,西安710054 [3]长安大学地球科学与资源学院,西安710054

出　　处：《矿产勘查》2020年第6期1093-1100,共8页Mineral Exploration

基　　金：中国地质调查局项目(编号:DD2019057009)资助。

摘　　要：结合花岗岩类的构造环境,通过对大量的岩石地球化学数据统计分析,总结了不同类型花岗岩的Na2O和K2O的含量变化,认为不同构造类型花岗岩的Na2O和K2O的含量变化可以用鲍文反应序列来解释。在一个构造演化越到晚期,岩浆分异程度越高,形成的花岗岩含K矿物越来越多,K2O含量越高,Na2O含量越低,反之,形成的花岗岩类K2O含量越低,Na2O含量越高。因此,可以认为,在早期大陆裂谷期由于岩石圈壳幔作用强烈,花岗岩分异程度中等,Na2O含量略小于或约等于K2O;到大洋形成时期,洋中脊出现,岩浆分异的程度应该非常低,Na2O>>K2O;收缩环境下形成的花岗岩分异程度较低,因此,岛弧环境的花岗岩Na2O>K2O;大洋闭合陆陆碰撞环境形成的花岗岩分异程度适中,Na2O≈K2O;造山环境的花岗岩分异程度较高,Na2O﹤K2O。花岗岩的Na2O和K2O的含量变化及Na2O/K2O值基本可以反映花岗岩的构造环境。Combined with tectonic environment of granitoids,use a large rock geochemical data for statistical analysis,summarized the Na2O and K2O changes in different types of granite,consider that we can use Bowen reaction sequence to explain the Na2O and K2O changes of the different types of granite.Differentiation of tectonic and magmatic evolution has synchronization,the granite of late in tectonic evolution that can engender more and more Potassium mineral,the higher the K2O content,the lower the Na2O content,conversely,the lower the K2O content of granite,the higher the Na2O content.Therefore,it is considered that lithospheric have a strong crust-mantle interaction in early the continental rift,Degree of granite differentiation medium,Na2O content is slightly less than or equal to about K2O;into the period of ocean forming,magmatic differentiation degree is very low of mid-ocean ridge environment,Na2O>>K2O.Granite differentiation degree is low in the contracting environment,so the granite of island arc environment Na2O>K2O;there is a moderate differentiation degree of the granite in continental collision environment,Na2O≈K2O;there is a high differentiation degree of the granite in orogenic environment,Na2O<K2O.Na2O and K2O content change and Na2O/K2O can basic tectonic environment of granite.

关 键 词：花岗岩类 构造环境 Na2O和K2O 含量变化 

分 类 号：P588.11[天文地球—岩石学]