| 江西相山酸性火山-侵入杂岩精确年代学与演化序列研究 |
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| 引用本文： | 郭福生,杨庆坤,谢财富,孟祥金,周万蓬,姜勇彪,张树明,吴志春.江西相山酸性火山-侵入杂岩精确年代学与演化序列研究[J].地质科学,2015,0(3):684-707. |
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| 作者姓名： | 郭福生 杨庆坤 谢财富 孟祥金 周万蓬 姜勇彪 张树明 吴志春 |
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| 作者单位： | 1. 东华理工大学地球科学学院 南昌 330013;
2. 中国地质大学(北京)北京 100083;
3. 中国地质科学院地质研究所 北京 100037 |
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| 摘 要： | 相山火山盆地主体岩石为一套由熔结凝灰岩、流纹英安岩、流纹英安斑岩、碎斑熔岩、粗斑花岗斑岩及似斑状花岗岩组成的酸性火山-侵入杂岩体, 构成了两个完整的喷发-溢流(侵出)-侵入的岩浆活动亚旋回。本文在野外地质调查的基础上, 采用SIMS、LA-ICP-MS技术对主要岩类进行了高精度的锆石U-Pb年代学研究, 并建立了火山-侵入杂岩体的演化序列。结果表明, 打鼓顶组熔结凝灰岩代表了相山火山-侵入活动的最早期产物, 其锆石U-Pb年龄为140.7±2.7 Ma、140.1±1.8 Ma和138.2±1.6 Ma, 第一亚旋回主体流纹英安岩的锆石U-Pb年龄135.0±1.8 Ma。鹅湖岭组熔结凝灰岩代表了火山-侵入活动的第二亚旋回的开始, 其U-Pb年龄为135.6±1.2 Ma, 第二亚旋回主体碎斑熔岩的锆石U-Pb年龄133.6±1.3 Ma, 沙洲单元的粗斑花岗斑岩和似斑状花岗岩属于该亚旋回最晚期的侵入岩, 其锆石U-Pb年龄代表了相山火山-侵入活动的结束时间(分别为133.4±1.2 Ma和133.9±1.1 Ma)。相山早白垩世火山-侵入活动延续时间较短, 整体上呈现一个连续的过程, 初始时间在141 Ma附近, 结束时间在132 Ma左右。概言之, 第一亚旋回(141~135 Ma)以形成熔结凝灰岩、流纹英安岩和流纹英安斑岩为主, 第二亚旋回(135~132 Ma)以熔结凝灰岩、碎斑熔岩、粗斑花岗斑岩和似斑状花岗岩为主。岩石地球化学和野外地质特征也与两个亚旋回火山-侵入岩浆活动相吻合。
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| 关 键 词： | 锆石U-Pb年代学 演化序列 火山-侵入杂岩体 相山 |
| 收稿时间： | 2014-09-19 |
| 修稿时间： | 2014-09-19; |
Zircon geochronology and evolution sequence of the acidic volcano-intrusive complex from Xiangshan,Jiangxi Province |
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| Guo Fusheng,Yang Qingkun,Xie Caifu,Meng Xiangjin,Zhou Wanpeng,Jiang Yongbiao,Zhang Shuming,Wu Zhichun.Zircon geochronology and evolution sequence of the acidic volcano-intrusive complex from Xiangshan,Jiangxi Province[J].Chinese Journal of Geology,2015,0(3):684-707. |
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| Authors: | Guo Fusheng Yang Qingkun Xie Caifu Meng Xiangjin Zhou Wanpeng Jiang Yongbiao Zhang Shuming Wu Zhichun |
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| Institution: | 1. East China institute of technology, Nanchang 330013;
2. China University of Geoscieces(Beijing), Beijing 100083;
3. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037 |
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| Abstract: | The host rocks of Xiangshan volcanic basin are volcanic-intrusive complex, involves the welded tuff, rhyolite dacite, rhyolite dacite porphyry, porphyroclastic lava, macrophyric granite porphyry and porphyritic granite, constitutes two complete magmatism sub cycle of eruption-overflow(intrusive)-intrusive. The authors use SIMS, LA-ICP-MS technology to analyze the zircon U-Pb geochronology on the main rocks and discuss the origin and evolution characteristics of Xiangshan complex. The results show that, ignimbrite of Daguding Formation represents the early outcome of Xiangshan volcanic intrusive activities, the zircon U-Pb age is 140.7±2.7 Ma, 140.1±1.8 and 138.2±1.6 Ma, U-Pb zircon age of rhyodacite is 135±1.8 Ma. Ignimbrite of Ehuling Formation represents the second begining of the volcanic intrusive activities and the U-Pb age is 135.6±1.2 Ma. Zircon U-Pb age of porphyroclastic pava is 133.6±1.3 Ma. Macrophyric granite porphyry and porphyritic granite are the youngest rocks and the zircon U-Pb age(133.4±1.2 Ma and 133.9±1.1 Ma, respectively)represents the end of the volcanic intrusive activity. From the Early Cretaceous, the duration of the Early Cretaceous volcanic intrusive activity is short, showing a continuous process, with the beginning is about 141 Ma and the end is about 132 Ma. The Xiangshan volcanic intrusive activity takes on two sub cycles. In the first sub cycle(141~135 Ma), the magmatites involve welded tuff, rhyolite dacite and rhyodacite porphyry, while the second sub cycles(135~132 Ma)involve ignimbrite, porphyroclastic lava, macrophyric granite porphyry and porphyritic granite. Rock geochemical and geological features are inconsistent with the evolution sequence. |
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| Keywords: | Zircon U-Pb geochronology Evolution sequence Volcanic-intrusive complex Xiangshan |
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