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引用本文:刘浪,刘德民,邵俊琦,丁国立,黄彬彬,黄锦山. 云南会泽地区玄武粗安岩年代学、地球化学及构造演化[J]. 中国地质, 2020, 47(3): 678-692.
LIU Lang,LIU Demin,SHAO Junqi,DING Guoli,HUANG Binbin,HUANG Jinshan. Geochronology, geochemistry and tectonic evolution of the basaltic trachyandesite in Huize, northeastern Yunnan Province[J]. Geology in China, 2020, 47(3): 678-692(in Chinese with English abstract).
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云南会泽地区玄武粗安岩年代学、地球化学及构造演化
刘浪1, 刘德民1, 邵俊琦1, 丁国立2, 黄彬彬1, 黄锦山1
1.中国地质大学 (武汉) 地球科学学院, 湖北 武汉 430074;2.福建省地质调查研究院, 福建 福州 350013
摘要:
滇东北会泽地区发现峨眉山玄武岩中沿NNE向发育的玄武粗安岩,通过详细的野外地质调查、镜下岩相学分析、锆石U-Pb定年以及岩石地球化学测试等方法,研究了该玄武粗安岩形成年龄,地球化学特征及其指示的构造演化过程。LA-ICP-MS锆石U-Pb年代学确定玄武粗安岩形成的加权年龄为(251.6±4.2)Ma(MSWD=0.20),蚀变年龄分别为(143.5±1.9)Ma和(150.5±2.4)Ma。岩石地球化学主量、稀土和微量元素测试表明,玄武粗安岩的SiO2含量在52.09%~54.10%,属于中基性火山岩;Mg#介于19.88~40.86,在TAS图解上整体显示为碱性玄武岩粗安岩系列;稀土元素和微量元素特征显示出会泽玄武粗安岩来自交代的富集地幔源区,岩浆演化过程中发生了一定的单斜辉石、斜长石和磁铁矿的分离结晶作用。会泽玄武粗安岩是峨眉山玄武岩的一部分,推断其为峨眉山地幔柱活动消亡期的产物。
关键词:  玄武粗安岩  二叠纪  地幔柱  板内环境  地质调查工程  会泽  云南
DOI:10.12029/gc20200309
分类号:P541;P581
基金项目:广西干热岩资源调查项目(2019016207)、中国地质调查局地质矿产综合调查项目(12120115041601)及“云南会泽县待补地区小米落褶皱变形特征与构造演化”专题项目(2015014062)共同资助。
Geochronology, geochemistry and tectonic evolution of the basaltic trachyandesite in Huize, northeastern Yunnan Province
LIU Lang1, LIU Demin1, SHAO Junqi1, DING Guoli2, HUANG Binbin1, HUANG Jinshan1
1.School of Earth Sciences, China University of Geosciences, Wuhan 430074, Hubei, China;2.Fujian Institute of Geological Survey, Fuzhou 350013 Fujian, China
Abstract:
Several small-scale basalt trachyandesite rock masses were found in NNE direction in Emeishan basalts of Huize area, northeastern Yunnan Province. Based on detailed field geological survey, microscopic petrographic analysis, zircon U-Pb dating and rock geochemical test, the authors studied the formation age and geochemical characteristics of these basalt trachyandesites and their tectonic evolution process. LA-ICP-MS zircon U-Pb dating yielded a weighted mean 206Pb/238U age of(251.6±4.2)Ma (MSWD=0.20) for the basalt trachyandesite, and the alteration ages are(143.5±1.9) Ma and(150.5±2.4) Ma, respectively. The content of SiO2 in basalt trachyandesite is between 52.09%-54.10%, implying that it belongs to the intermediate basic volcanic rock. The Mg# values of basalt trachyandesite are from 19.88 to 40.86, and the TAS diagram generally shows that it belongs to alkali basalt trachyandesite series. The characteristics of REE and trace elements show that the basalt trachyandesite of Huize was derived from enriched mantle source. In the process of magmatic evolution, a part of clinopyroxene, plagioclase and magnetite experienced fractional crystallization. It is considered that the basalt trachyandesite of Huize is a part of Emeishan basalts, and that it might have been the product of the extinction of Emeishan mantle plume.
Key words:  basaltic trachyandesite  Permian  mantle column  plate internal environment  geological survey engineering  Huize  Yunnan Province