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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.
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(in Chinese with English abstract).
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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
刘军平1, 孙柏东1, 崔晓庄2, 熊波1, 宋冬虎1, 白春东3, 张坤1, 杨仕潘1
1.云南省地质调查院, 云南 昆明 650216;2.中国地质调查局成都地质调查中心, 四川 成都 610081;3.河北省区域地质调查院, 河北 廊坊 065000
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。
关键词:  锆石U-Pb测年  A型花岗岩  Rodinia超大陆  地质调查工程  安宁  云南
DOI:10.12029/gc20200310
分类号:P588.12;P597
基金项目:云南省国土资源厅基金项目“云南省1∶5万撒马基幅、因民幅、贵城幅、舒姑幅区域地质调查(D201905)”及中国地质调查局项目“云南1∶5万二街、易门、鸣矣河、上浦贝幅区域地质调查”(DD20160017)、“云南区域地质调查片区总结与服务产品开发”(121201102000150012-02)共同资助。
Geochronology, geochemistry, zircon Hf isotopic composition and genesis of Shihushan granite in Anning, Yunnan Province
LIU Junping1, SUN Baidong1, CUI Xiaozhuang2, XIONG Bo1, SONG Donghu1, BAI Chundong3, ZHANG Kun1, YANG Shipan1
1.Yunnan Institute of Geological Survey, Kunming 650216, Yunnan, China;2.Chengdu Center, China Geological Survey, Chengdu 610081, Sichuan, China;3.Hebei Institute of Geological Survey, Langfang 065000, Hebei, China
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.
Key words:  zircon U-Pb dating  A-type granite  Rodinia supercontinent  geological survey engineering  Anning  Yunnan