青海都兰县色德日辉绿岩地球化学特征、锆石U-Pb年龄及其地质意义

发布时间：2018-04-17 12:02

本文选题：LA-ICP-MS锆石U-Pb年龄 + 岩石成因　；参考：《矿物岩石地球化学通报》2017年02期

【摘要】：为探讨青海都兰县沟里地区基性脉岩的成岩时代与构造环境,理解早古生代东昆仑地区的地质演化历史,对沟里地区发育的色德日辉绿岩进行了系统的岩石学、岩石地球化学和锆石U-Pb年代学研究。岩石学观察显示,色德日辉绿岩蚀变强烈,但仍保留明显的辉绿结构。岩石地球化学分析表明,辉绿岩的SiO_2含量(45.70%~46.70%)与基性岩相当,属亚碱性玄武岩系列;全岩的CaO含量较高(19.64%~21.50%),与碳酸盐化、云母化等蚀变特征吻合;全岩稀土总量较低(64.53×l0-6~182.99×l0~(-6)),具有轻稀土元素富集特征,其δEu为0.80~0.96、δCe为0.84~0.92,均呈负异常;富集大离子亲石元素(Rb、Th和U),而亏损高场强元素(Nb、Ta、Ti和Y)。全岩地球化学特征呈现岛弧玄武岩特征。LA-ICP-MS锆石U-Pb年龄为417.4±3.2Ma,形成于晚志留世。研究表明,色德日辉绿岩是俯冲板片的消减作用引发地幔物质产生部分熔融的产物,其形成与晚志留世东昆仑地区古特提斯洋壳俯冲消减作用有关。
[Abstract]:In order to study the diagenetic age and tectonic environment of basic dikes in Guli area, Dulan County, Qinghai Province, and to understand the history of geological evolution in the East Kunlun area of early Paleozoic, a systematic petrology was carried out on the Sederi diabase developed in Goulan area, Qinghai Province.Geochemistry and U-Pb chronology of zircon.Petrological observations show that the diabase is strongly altered, but still retains a distinct phosphorescence structure.The petrogeochemical analysis shows that the SiO_2 content of diabase is similar to that of basic rock and belongs to the subalkaline basalt series, and the CaO content of the whole rock is higher (19.64% and 21.50%), which coincides with the alteration characteristics of carbonation and mica.The total amount of rare earth elements in the whole rock is relatively low (64.53 脳 l0-6n 182.99 脳 10 ~ (-1)), which is characterized by the enrichment of light rare earth elements (未 EU = 0.80 ~ 0.96, 未 ce = 0.840.92), and the enrichment of large ion lithophile elements RbTh and UB, while the depletion of high field strong elements NbTh and YU.The geochemical characteristics of the whole rock show that the island arc basalt features. LA-ICP-MS zircon U-Pb age is 417.4 卤3.2 Ma.It was formed in the late Silurian.The results show that the diabase is the product of partial melting of mantle material caused by subduction plate subduction, and its formation is related to the subduction of paleoTethys oceanic crust in the late Silurian East Kunlun area.
【作者单位】：中化地质矿山总局云南地质勘查院;中国科学院地球化学研究所矿床地球化学国家重点实验室;昆明理工大学国土资源工程学院;昆明理工大学资产管理处;
【基金】：国家自然科学基金项目(41272111) 山东黄金集团基本科研业务费专项基金项目(201122010100)
【分类号】：P588.124;P597.3

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