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| 基金项目：中国地质调查局项目“全国陆域及海区地质图件更新与共享”子项目“云南省系列地质图件数据处理与洋板块地质研究”（DD20190370） |
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| 摘要： |
| 宁洱新生代玄武岩主要分布于宁洱县城与通关周围，玄武岩覆盖在下白垩统之上，主要由橄榄玄武岩及橄斑玄武岩组成，具气孔构造，斑状结构，含有较多的斜长石斑晶。宁洱新生代玄武岩为碱性玄武岩，其特征为大离子亲石元素Ba和高场强元素Nb、Ta、Zr、Th较为富集，Ti、Al含量较高，Si含量低，轻重稀土元素分异较明显，表现出明显的Eu正异常，δEu平均值为1.34。宁洱玄武岩的地球化学特征显示其来自于陆内裂谷环境，岩浆来自于富集地幔，分离结晶作用较弱且几乎未受到地壳的混染作用。宁洱玄武岩形成于更新世时期，是兰坪—思茅盆地中轴构造活动剧烈导致新生代活动断裂相互错动，活跃岩浆迅速溢出地表的产物。区域内新生代的断裂构造具有裂谷的性质，可能处于裂谷形成的早期阶段。 |
| 关键词：玄武岩 新生代 地球化学 裂谷 兰坪—思茅盆地 云南宁洱 |
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| Abstract: |
| The Cenozoic basalts in Ning'er are mainly distributed around Ning'er County and Tongguan, covering the Lower Cretaceous. They are mainly composed of olivine basalts and ureilite basalts, with porosity and porphyritic structure, and contain plenty of plagioclase porphyrists. The Cenozoic basalts in Ning'er are alkaline basalts, which are rich in large ion lithophile elements such as Ba and high field strength elements such as Nb, Ta, Zr, Th, with a high content of Ti and Al, a low content of Si, and obvious differentiation of light and heavy rare-earth elements, showing obvious positive Eu anomaly with an average δEu value of 1.34. The geochemical characteristics of the basalts in Ning'er show that they come from intra-continental rift environment, their magma comes from enriched mantle, and the separation and crystallization of basalts are weak and hardly affected by crustal contamination. The basalt of Ning'er was formed in Pleistocene, which is the product of the intense axial tectonic activity of Lanping-Simao Basin, leading to the mutual dislocation of Cenozoic active faults and rapid surface overflow of active magma. The Cenozoic fault structure in the region has the property of rift valley, which may be in the early stage of rift formation. |
| Keywords:basalt Cenozoic geochemistry rift valley Lanping-Simao Basin Ning′er in Yunnan |
| 谭梅，莫雄，周冰洋，等.兰坪—思茅盆地宁洱地区新生代玄武岩地球化学特征及意义[J].地质学刊,2023,47(2):143-152 |
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