| 江西中部新丰街花岗质岩体LA-ICP-MS锆石U-Pb年代学、元素和Sr-Nd-Hf同位素地球化学特征及岩石成因 |
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| 引用本文： | 朱书奇,姜耀辉,王国昌,倪春雨,青龙.江西中部新丰街花岗质岩体LA-ICP-MS锆石U-Pb年代学、元素和Sr-Nd-Hf同位素地球化学特征及岩石成因[J].高校地质学报,2016,22(3):431. |
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| 作者姓名： | 朱书奇 姜耀辉 王国昌 倪春雨 青龙 |
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| 摘 要： | 对江西中部新丰街花岗质岩体开展了岩相学、LA-ICP-MS锆石U-Pb年代学以及元素和Sr-Nd-Hf同位素地球化学研
究，并探讨了岩石成因及其构造意义。结果表明，新丰街岩体由二云母花岗岩和黑云母花岗组成；两者均形成于晚侏罗世
（~148 Ma）；二云母花岗岩SiO2含量为75.71%~78.36%，为弱过铝质-强过铝质岩石，属高钾钙碱性系列，Mg#变化于0.26~
0.34，具有较低的Ga/Al比值（绝大部分<2.6×10-4） 和较低的Zr+Nb+Ce+Y含量（<350×10-6），全岩εNd(t)为-10~-8.2，锆石原
位εHf(t)为-15.7~-9.4；黑云母花岗岩SiO2含量为71.25%~74.41%，主要为准铝质-弱过铝质岩石，也属于高钾钙碱性系列，
Mg#变化于0.32~0.37，同样具有较低的Ga/Al比值（绝大部分<2.6×10-4） 和较低的Zr+Nb+Ce+Y含量（<350×10-6），全岩初始
87Sr/86Sr比值为0.7136~0.7153，εNd(t)为-10.0~-8.9，锆石原位εHf(t)值为-16.5~-10.9。通过综合研究认为二云母花岗岩具有S
型花岗岩特征，是由下地壳中变质泥岩在相对较低温度下发生部分熔融而形成的；黑云母花岗岩具有I型花岗岩特征，是由下
地壳中长英质火成岩在相对较高温度下发生部分熔融而形成的。岩体侵位于由古太平洋板块俯冲引起的陆缘弧构造环境。
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| 关 键 词： | 新丰街岩体 江西中部 LA-ICP-MS锆石U-Pb年龄 Sr-Nd-Hf同位素 S型和I型花岗岩 |
LA-ICP-MS Zircon U-Pb Geochronology,Elemental and Sr-Nd-Hf Isotopic Geochemistry of the Xinfengjie Granitic Intrusion in Central Jiangxi Province,SE China,and Its Petrogenesis |
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| ZHU Shuqi,JIANG Yaohui,WANG Guochang,NI Chunyu,QING Long.LA-ICP-MS Zircon U-Pb Geochronology,Elemental and Sr-Nd-Hf Isotopic Geochemistry of the Xinfengjie Granitic Intrusion in Central Jiangxi Province,SE China,and Its Petrogenesis[J].Geological Journal of China Universities,2016,22(3):431. |
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| Authors: | ZHU Shuqi JIANG Yaohui WANG Guochang NI Chunyu QING Long |
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| Abstract: | In this study, we present detailed LA-ICP-MS zircon U-Pb chronology, major and trace elements, and Sr-Nd-Hf isotopic
data for the Xinfengjie pluton in central Jiangxi province, and discuss its petrogenesis and tectonic implications. Our results show
that the Xinfengjie granites are composed of two-mica granites and biotite granites, both of which were formed in late Jurassic (ca.
148 Ma). The two-mica granites have SiO2 contents of 75.71~78.36%. They are weakly peraluminous to strongly peraluminous rocks,
and belong to high-K calc-alkaline series. Their Mg# vary from 0.26 to 0.34, and they have low Ga/Al ratios (mostly < 2.6×10-4) and low
Zr+Nb+Ce+Y contents (<350×10-6). They have whole-rack εNd(t) of -10~-8.2, and zircon in-situ εHf(t) of -15.7~-9.4. The biotite
granites have SiO2 contents of 71.25~74.41% . They are metaluminous to weakly peraluminous rocks, and also belong to high-Kcalc-alkaline series. Their Mg# vary from 0.32 to 0.37, and they also have low Ga/Al ratios (mostly < 2.6×10-4) and low Zr+Nb+Ce+Y
contents (<350×10-6). They have initial 87Sr/86Sr ratios of 0.7136~0.7153, εNd(t) of -10.0~-8.9, and zircon in-situ εHf(t ) of -16.5~-10.9.
Through our comprehensive research, we consider that the two-mica granites show characteristics of S-type granites, and were formed at
lower temperature by partial melting of meta-pelite in the lower crust, while the biotite granites exhibit I-type affinity, and were formed
at higher temperature by partial melting of felsic rocks in the lower crust. This pluton emplaced in a continental-arc tectonic regime
which was induced by the subduction of the paleo-pacific plate. |
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| Keywords: | Xinfengjie granites Central Jiangxi province LA-ICP-MS zircon U-Pb age Sr-Nd-Hf isotopes S- and I-type granites |
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