| 南大巴山东段上奥陶统五峰组-下志留统龙马溪组钾质斑脱岩锆石U- Pb年龄及其构造意义 |
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| 引用本文： | 熊国庆,王剑,李园园,余谦,门玉澎,周小琳,熊小辉,周业鑫,杨潇.南大巴山东段上奥陶统五峰组-下志留统龙马溪组钾质斑脱岩锆石U- Pb年龄及其构造意义[J].地质学报,2019,93(4):843-864. |
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| 作者姓名： | 熊国庆 王剑 李园园 余谦 门玉澎 周小琳 熊小辉 周业鑫 杨潇 |
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| 作者单位： | 成都理工大学地球科学学院,成都,610059;中国地质调查局成都地质调查中心,成都,610081;国土资源部沉积盆地与油气资源重点实验室,成都,610081;山东省物化探勘查院,济南,250013;中国地质调查局成都地质调查中心,成都,610081;国土资源部沉积盆地与油气资源重点实验室,成都,610081 |
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| 基金项目： | 本文为国家自然科学基金项目（编号：41672112，41372124）、四川盆地龙马溪组页岩气战略选区调查（编号：DD20160193）、重庆市页岩气勘探有利区带优选及资源量评价研究（渝东北）及重庆市页岩气专项地质调查（渝东北）共同资助的成果。 |
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| 摘 要： | 奥陶系-志留系之交的钾质斑脱岩分布范围广,发育层位多,是研究该时期地层年代学、事件地层对比、生物大灭绝和冰期事件及源区构造背景分析的理想对象。本文对南大巴山东段鄂渝交界上奥陶统五峰组-下志留统龙马溪组地层中的斑脱岩开展了锆石U-Pb测年,栗子坪剖面(LZP)黑色泥岩中钾质斑脱岩获得了447.9±2.9Ma年龄,燕子剖面(YZ)黑色硅质岩中钾质斑脱岩年龄为450.9±1.6Ma,间接地限定和约束了地层的沉积年龄。岩石地球化学特征显示,燕子剖面斑脱岩SiO_2为53.61%～56.34%,而栗子坪剖面SiO_2为35.56%～43.81%,其低值可能与高铁含量和高烧失量有关;K_2O含量为5.61%～5.47%,且K_2ONa_2O,属钾质斑脱岩。燕子剖面和栗子坪剖面钾质斑脱岩稀土元素含量变化较大,前者ΣREE为46.48×10~(-6)～73.70×10~(-6),平均值63.08×10~(-6),后者ΣREE介于113.34×10~(-6)～356.98×10~(-6)之间,平均值164.08×10~(-6),LREE/HREE和La_N/Yb_N均显示轻、重稀土元素分异不太明显,轻稀土轻微富集的特点;两者均具有明显的Eu负异常,Ba、U、Nb和Ti微量元素分异明显,前者微量元素明显亏损Nb、Ta和Ti(TNT异常)。原岩恢复结果表明LZP钾质斑脱岩的原始岩浆为过碱性粗面安山岩,YZ钾质斑脱岩为高钾碱性流纹岩,表明两者可能属不同期次或不同来源的岩浆岩。构造背景判别图解显示,LZP样品主要落入板内花岗岩内;YZ样品落在火山弧花岗岩/同碰撞花岗岩内。结合大巴山区域地质构造背景,笔者认为～450.9Ma钾质斑脱岩可能与古秦岭洋壳向北的俯冲有关,其火山凝灰质可能源自沿古秦岭洋盆北缘的火山弧喷发;～447.9Ma钾质斑脱岩与板内拉张有关,火山物质可能主要以板内火山喷发为主。
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| 关 键 词： | 南大巴山东段 上奥陶统五峰组-下志留统龙马溪组 锆石U-Pb测年 钾质斑脱岩 构造判别图解 |
| 收稿时间： | 2018/5/16 0:00:00 |
| 修稿时间： | 2018/8/30 0:00:00 |
Zircon U- Pb dating of K- bentonite from Late Ordovician Wufeng Formation and Earlier Silurian Longmaxi Formation in the eastern section of south Dabashan and its tectonic signification |
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| Xiong Guoqing,Wang Jian,Li Yuanyuan,Yu Qian,Men Yupeng,Zhou Xiaolin,Xiong Xiaohui,Zhou Yexin and Yang Xiao.Zircon U- Pb dating of K- bentonite from Late Ordovician Wufeng Formation and Earlier Silurian Longmaxi Formation in the eastern section of south Dabashan and its tectonic signification[J].Acta Geologica Sinica,2019,93(4):843-864. |
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| Authors: | Xiong Guoqing Wang Jian Li Yuanyuan Yu Qian Men Yupeng Zhou Xiaolin Xiong Xiaohui Zhou Yexin and Yang Xiao |
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| Institution: | 1) College of Earth Science, Chengdu University of Technology, Chengdu, 610059;2) Chengdu center of Geological Suvery, China Geological Survey, MLR, Chengdu, 610081;3) Key Laboratory of Sedimentary Basin & Oil and Gas Resources, MLR, Chengdu, 610082,1) College of Earth Science, Chengdu University of Technology, Chengdu, 610059;2) Chengdu center of Geological Suvery, China Geological Survey, MLR, Chengdu, 610081;3) Key Laboratory of Sedimentary Basin & Oil and Gas Resources, MLR, Chengdu, 610082,4) Shandong Institute of Geophysical & Geochemical Exploration, Jinan, 250013,2) Chengdu center of Geological Suvery, China Geological Survey, MLR, Chengdu, 610081;3) Key Laboratory of Sedimentary Basin & Oil and Gas Resources, MLR, Chengdu, 610082,2) Chengdu center of Geological Suvery, China Geological Survey, MLR, Chengdu, 610081;3) Key Laboratory of Sedimentary Basin & Oil and Gas Resources, MLR, Chengdu, 610082,1) College of Earth Science, Chengdu University of Technology, Chengdu, 610059;2) Chengdu center of Geological Suvery, China Geological Survey, MLR, Chengdu, 610081;3) Key Laboratory of Sedimentary Basin & Oil and Gas Resources, MLR, Chengdu, 610082,2) Chengdu center of Geological Suvery, China Geological Survey, MLR, Chengdu, 610081;3) Key Laboratory of Sedimentary Basin & Oil and Gas Resources, MLR, Chengdu, 610082,1) College of Earth Science, Chengdu University of Technology, Chengdu, 610059;2) Chengdu center of Geological Suvery, China Geological Survey, MLR, Chengdu, 610081;3) Key Laboratory of Sedimentary Basin & Oil and Gas Resources, MLR, Chengdu, 610082 and 1) College of Earth Science, Chengdu University of Technology, Chengdu, 610059;2) Chengdu center of Geological Suvery, China Geological Survey, MLR, Chengdu, 610081;3) Key Laboratory of Sedimentary Basin & Oil and Gas Resources, MLR, Chengdu, 610082 |
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| Abstract: | |
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| Keywords: | eastern section of south Dabashan Late Ordovician Wufeng Formation and Earlier Silurian Longmaxi Formation zircon U- Pb dating K- bentonite discrimination diagram of tectonic setting |
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