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    刘军平, 孙柏东, 崔晓庄, 熊波, 宋冬虎, 白春东, 张坤, 杨仕潘. 云南安宁地区石虎山花岗岩年代学、地球化学特征和锆石Hf同位素组成及其成因[J]. 中国地质, 2020, 47(3): 693-708. DOI: 10.12029/gc20200310
    引用本文: 刘军平, 孙柏东, 崔晓庄, 熊波, 宋冬虎, 白春东, 张坤, 杨仕潘. 云南安宁地区石虎山花岗岩年代学、地球化学特征和锆石Hf同位素组成及其成因[J]. 中国地质, 2020, 47(3): 693-708. DOI: 10.12029/gc20200310
    LIU Junping, SUN Baidong, CUI Xiaozhuang, XIONG Bo, SONG Donghu, BAI Chundong, ZHANG Kun, YANG Shipan. Geochronology, geochemistry, zircon Hf isotopic composition and genesis of Shihushan granite in Anning, Yunnan Province[J]. GEOLOGY IN CHINA, 2020, 47(3): 693-708. DOI: 10.12029/gc20200310
    Citation: LIU Junping, SUN Baidong, CUI Xiaozhuang, XIONG Bo, SONG Donghu, BAI Chundong, ZHANG Kun, YANG Shipan. Geochronology, geochemistry, zircon Hf isotopic composition and genesis of Shihushan granite in Anning, Yunnan Province[J]. GEOLOGY IN CHINA, 2020, 47(3): 693-708. DOI: 10.12029/gc20200310

    云南安宁地区石虎山花岗岩年代学、地球化学特征和锆石Hf同位素组成及其成因

    Geochronology, geochemistry, zircon Hf isotopic composition and genesis of Shihushan granite in Anning, Yunnan Province

    • 摘要: 石虎山花岗岩岩体位于安宁市德滋村附近,本文对该岩体开展了LA-ICP-MS锆石U-Pb定年、岩石地球化学、锆石Hf同位素组成研究。结果获得(616±20)Ma的岩浆结晶年龄和(839±17)Ma、(766±15)Ma、(705.5±9.4)Ma的继承性年龄,说明岩体形成于新元古代埃迪卡拉纪;其中(839±17)Ma、(766±15)Ma、(705.5±9.4)Ma的继承性年龄组合可能是Rodinia超大陆裂解构造过程的记录,839 Ma、616 Ma可能是Rodinia超大陆在扬子板块西缘开始裂解与最终裂解时限。花岗岩主量、微量元素特征显示,其产生于伸展环境的高硅、过铝、高钾的A型花岗岩;锆石εHft)值均小于0,在t-t(Ma)和t-(176Hf/177Hf)图上,所有样品点均落在上地壳演化线之上,二阶段模式年龄变化范围为1.77~2.31 Ga,结合Nb/Y—Rb/Y图解,表明成岩物质主要来源于古元古代古老下地壳页岩60%部分熔融。

       

      Abstract: The LA-ICP-MS zircon U-Pb age, rock geochemistry and zircon Hf isotopic composition of the Shihushan granite located in Dezi Village of Anning area were investigated in this study. The zircon U-Pb dating yielded a magmatic crystallization age of (616±20) Ma and inherited ages of (839±17) Ma, (766±15) Ma and (705.5±9.4) Ma, indicating pluton emplacement in Neoproterozoic Ediacaran Stage. The authors hold that the magmatic crystallization age of (616±20) Ma indicates the pluton emplacement in Neoproterozoic Ediacaran Stage, and the assemblage of inherited ages of (839±17) Ma, (766±15) Ma and (705.5±9.4) Ma represents the splitting of the Rodinia supercontinent. The age of (839±17) Ma may represent the initiation of the breakup of the Rodinia supercontinent, while the age of (616±20) Ma may represent the final stage of the breakup event. The major and trace elements of alkali feldspar granite show the characteristics of A-type granite with high SiO2-K2O-Al2O3 content, indicating an extensional environment. Zircons from samples have low εHf(t) value (< 0). All samples are plotted on the upper crustal evolution area on t-t (Ma) and t-(176Hf/177Hf) diagrams. The two-stage Hf model ages range from 1.77 Ga to 2.31 Ga. According to the Nb/Y-Rb/Y diagram, the petrogenic material mainly originated from the 60% melting of the shale of the Paleoproterozoic lower crust.

       

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