镜泊湖地区杏山火山群的火山岩特征及其岩浆演化  

The volcanic rock characteristics and magmatic evolution of the Xingshan Volcano Group in the Jingpo Lake area

作　　者：郭可欣 刘永顺[1] 聂保锋[1] 郭磊 张辉 黄志聪 侯鹏 李耀 GUO Kexin;LIU Yongshun;NIE Baofeng;GUO Lei;ZHANG Hui;HUANG Zhicong;HOU Peng;LI Yao(College of Resource,Environment and Tourism,Capital Normal University,Beijing,100048)

机构地区：[1]首都师范大学资源环境与旅游学院,北京100048

出　　处：《地质论评》2024年第1期137-154,共18页Geological Review

基　　金：国家自然科学基金资助项目(编号:41372343,40872062)的成果。

摘　　要：镜泊湖火山区是我国陆内新生代玄武岩研究的一个重要窗口。东南部的杏山火山群研究不足且前人的研究否定了其岩浆经历过同化混染作用。笔者等对杏山火山群的玄武岩开展了系统的岩石学、岩石地球化学和Sr—Nd—Pb同位素的研究,认为杏山火山群主要为碧玄岩和粗面玄武岩,原生岩浆在上升过程中发生了橄榄石和单斜辉石的分离结晶,并在上地壳区域发生了同化混染作用,但同化混染—分离结晶作用较为微弱。将杏山火山群与同期的镜泊湖玄武岩对比发现,两个地区的玄武岩都来源于石榴子石橄榄岩的部分熔融,杏山火山群的部分熔融程度略低于同期的镜泊湖玄武岩。在岩浆源区方面,杏山火山群的岩浆源区为普通地幔与全硅酸盐地球端元的混合源。岩浆源区的不均一性和岩浆演化过程中所经历的同化混染作用是造成杏山火山群和镜泊湖火山群的岩性差异的主要影响因素。Volcanic field in Jingpo Lake area is an important window for the study of intra-continental Cenozoic basalts.Previous studies on the Xingshan Volcano Group located in the southeast of this area have rarely been conducted and the possibility of magma assimilation and mixing in this area has been denied.The basalts of the Xingshan Volcano Group have been systematically studied in terms of petrology,petrochemistry and Sr—Nd—Pb isotopes.It is believed that the basalts of the Xingshan Volcano Group are mainly basanites and trachy-basalts.The fractionation of olivine and clinopyroxene occurred during the ascent of the primary magma,and the assimilation and mixing occurred in the upper crust,with weak AFC effect.The comparison between the basalts of the Xingshan Volcano Group and the Jingbohu basalts during the same eruption shows that the basalts in both areas are derived from the partial melting of garnet peridotite,and the partial melting degree of the Xingshan Volcano Group is slightly lower than that of Jingbohu basalts.In terms of magmatic source region,the Xingshan Volcano Group is the mixing source of PREMA and BSE end-member.The heterogeneity of magma source area and the assimilation and mixing during magma evolution are the main influencing factors that cause the difference between the lithologic features of the Xingshan Volcano Group and Jingpohu Volcano Group.

关 键 词：杏山火山群 中新世—更新世玄武岩 岩石化学 同化混染 地幔源区 

分 类 号：P588.1[天文地球—岩石学] P534.6[天文地球—地质学] P597.3