四川盐源长柏乡地区二叠纪玄武岩地质地球化学特征及成岩演化  

Geological and Geochemical Characteristics and Diagenetic Evolution of Permian Basalts in Changbai Township,Yanyuan,Sichuan

作　　者：周志敏 蔡云华 李钢 岳定强 杨晓凤 ZHOU Zhimin;CAI Yunhua;LI Gang;YUE Dingqiang;YANG Xiaofeng(Sichuan Comprehensive Geological Survey and Research Institute,Chengdu 610081,China;The 9th Geological Brigade of Sichuan Province,Deyang 618000,China)

机构地区：[1]四川省综合地质调查研究所,四川成都610081 [2]四川省第九地质大队,四川德阳618000

出　　处：《四川有色金属》2023年第3期41-46,共6页Sichuan Nonferrous Metals

基　　金：属于“西南三江成矿带南段地质矿产调查”子项目(项目编码:12120113048500),其任务书编号:基[2013]01-006-002。

摘　　要：本文探讨四川盐源长柏乡地区二叠纪玄武岩的岩浆演化及构造背景。所采玄武岩样品w(SiO_(2))为45.04%~54.05%,w(Na_(2)O+K_(2)O)为2.05%~5.26%,w(TiO_(2))为2.85%~4.40%,主要为高钾钙碱性、钙碱性高钛玄武岩。LREE/HREE比值为5.89~10.14,轻稀土元素富集。高场强元素Nb/U比值为22.20,Ce/Nb-Zr/Nb比值具明显的相关性,表明玄武岩受到地壳物质的强烈混染。具有较低的Mg#值(0.31~0.45),高的镁铁指数MF(69.70~80.90)和长英指数FL(15.57~86.80)表明岩浆分离结晶作用强。在Ta/Hf-Th/Hf图解上,样品投在地幔热柱玄武岩区和洋岛/海山玄武岩区。以上表明,所采样品的岩浆来源为富集地幔源区,为峨眉山地幔柱的产物。This article explores the magmatic evolution and tectonic background of the Permian basalts in the Changbai Township area of Yanyuan,Sichuan.The sampled basalt samples w(Si0_(2))range from 45.04% to 54.05%,w(Na_(2)0+K_(2)0)range from 2.05% to 5.26%,and w(Ti0_(2))range from 2.85% to 4.40%,mainly composed of high potassium calcium alkali and calcium alkali high titanium basalt.The LREE/HREE ratio ranges from 5.89 to 10.14,indicating enrichment of light rare earth elements.The Nb/U ratio of high field strength elements is 22.20,and the Ce/Nb Zr/Nb ratio has a significant correlation,indicating that the basalt is strongly contaminated by crustal materials.Having a low Mg# value(0.31~0.45),a high magnesium iron index MF(69.70~80.90),and a Changying index FL(15.57~86.80)indicate strong magma separation and crystallization.On the Ta/Hf Th/Hf diagram,the samples were deposited in the mantle plume basalt area and the oceanic island/seamount basalt area.The above indicates that the magma source of the collected samples is the enriched mantle source area,which is a product of the Emeishan mantle plume.

关 键 词：二叠纪玄武岩 岩石学 地球化学 成岩演化 四川盐源 

分 类 号：P618[天文地球—矿床学]