宾川—丽江地区二叠纪玄武岩 岩石地球化学特征及其成因

通过对云南省宾川—丽江地区岩石学和地球化学研究,系统阐述了玄武岩岩石地球化学及其岩浆活动特 征。认为研究区玄武岩可划分为高镁、低镁和过渡3个系列火山岩,其岩石地球化学性质呈现递变性,富集轻稀 土和大离子亲石元素,具有与洋岛玄武岩相似的地球化学特征,为板内拉张玄武岩。同时运用现代岩石成因理 论探讨了玄武岩的地幔源区特征、岩浆过程及可能的形成机制。运用多个玄武岩大地构造环境判别图解,确定 玄武岩形成于大陆拉张环境,与地幔柱活动有关。起源于地幔柱的岩浆与岩石圈相互作用,经历不同程度的壳 源混染,形成系列玄武岩。

Geochemical Characteristics and Origin of Permian Basalts in Binchuan-Lijiang Area,Yunnan Province

Applying modern theory of petrology formation, this paper described the petrochemistry and geochemistry characteristics of basalts and its magma activation in Binchuan-Lijiang area of Yunnan Province. Basalts occurring in the area can be compositionally subdivided into three types: the high-Mg(the contents of MgO is from 12.3% to 27. 2%), the low-Mg(the contents of MgO is from 2.48% to 7.53%)and transitional- Mg(the contents of MgO is from 10. 4% to 11. 3%). All three types show progressive variation of petrochemistry property and are enriched in LREE and LILE. They exhibit geochemical features similar to oceanic island basalts and contribute to tholeiitic basalts. From geochemical diagrams, it is found that the Emeishan basalts representing major magmatic events were induced by deep-seated plumes. The magma derived from the mantle plume interacts with lithospheric materials, underwent different degrees of mixing of lithospheric mantle and crustal components, and forms a variety of basalts.