| 内蒙古狼山地区侏罗系LA-ICP-MS碎屑锆石U-Pb定年及其物源意义 |
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| 引用本文： | 付星辉,赵红格,周义军,彭治超,蒋盛,张孙玄琦,王海然,李亚男.内蒙古狼山地区侏罗系LA-ICP-MS碎屑锆石U-Pb定年及其物源意义[J].地质通报,2016,35(12):2063-2075. |
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| 作者姓名： | 付星辉 赵红格 周义军 彭治超 蒋盛 张孙玄琦 王海然 李亚男 |
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| 作者单位： | 1. 西北大学地质学系, 陕西西安 710069;2. 西北大学大陆动力学国家重点实验室, 陕西西安 710069;3. 中石油东方地球物理公司研究院长庆分院, 陕西西安 710021;4. 西安地质矿产勘查开发院, 陕西西安 710100 |
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| 基金项目： | 西北大学大陆动力学国家重点实验室科技部专项项目（编号：BJ08133-14BJ081334-2）、国家自然科学基金项目（批准号：4133031540902032）、国家科技油气重大专项项目（编号：2011ZX05023-001-002）、中国地质调查局项目（编号：12120114009201） |
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| 摘 要： | 运用碎屑锆石LA-ICP-MS U-Pb测年和地球化学方法,对内蒙古狼山东升庙和义和久地区侏罗系石拐群物源进行了探讨。通过对111颗有效锆石年龄统计分析可知,年龄峰值以晚古生代(259~308Ma)为主,其次为古元古代(1.74~2.18Ga)和早古元古代—新太古代(2.39~2.58Ga)。晚古生代年龄与狼山大规模出露的海西期岩浆岩年龄一致,古元古代—新太古代年龄与狼山地区古元古代岩浆岩、孔兹岩带年龄分布特征相近。侏罗系砂岩稀土元素配分特征与海西期岩浆岩、乌拉山群、孔兹岩系相似。结合石拐群样品薄片和砾岩分析,认为侏罗系为近源沉积,其物源主要为狼山地区大规模海西期岩浆岩,其次来自河套地区孔兹岩带,狼山地区太古宙乌拉山群、古元古代岩浆岩和早—中三叠世岩浆岩可能提供了部分物源。另外,根据碎屑锆石最年轻年龄为243Ma(中三叠世),结合前人植物化石组合研究及狼山地区整体缺失三叠纪地层的特点,认为该套地层的时代应为早—中侏罗世。狼山地区侏罗系沉积物源模式为南北两侧为隆起物源区,主要物源为北侧狼山隆起,南侧河套隆起向北提供部分物源,不同地区物源存在一定差异。
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| 关 键 词： | 侏罗系 碎屑锆石U-Pb定年 沉积物源 海西期岩浆岩 孔兹岩带 |
| 收稿时间： | 2016/3/14 0:00:00 |
| 修稿时间： | 2016/4/28 0:00:00 |
Jurassic detrital zircon U-Pb dating of Langshan area, Inner Mongolia, and its provenance significance |
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| FU Xinghui,ZHAO Hongge,ZHOU Yijun,PENG Zhichao,JIANG Sheng,ZHANGSUN Xuanqi,WANG Hairan and LI Yanan.Jurassic detrital zircon U-Pb dating of Langshan area, Inner Mongolia, and its provenance significance[J].Geologcal Bulletin OF China,2016,35(12):2063-2075. |
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| Authors: | FU Xinghui ZHAO Hongge ZHOU Yijun PENG Zhichao JIANG Sheng ZHANGSUN Xuanqi WANG Hairan and LI Yanan |
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| Institution: | 1. Department of Geology, Northwestern University, Xi''an 710069, Shaanxi, China;2. State Key Laboratory of Continental Dynamics, Northwestern University, Xi''an 710069, Shaanxi, China;3. Changqing Branch of Geophysical Research Institute, BGP, CNPC, Xi''an 710021, Shaanxi, China;4. Xian Institute of Geological and Mineral Exploration, Xi''an 710100, Shaanxi, China |
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| Abstract: | The Jurassic provenance in Langshan area is discussed on the basis of detrital zircon LA-ICP-MS U-Pb dating and geochemical methods. Two sandstone samples were selected from Jurassic Shiguai Group from Dongsheng Temple and Yihejiu area. The statistical data of 111 valid detrital zircons ages reveal that zircon ages have three peaks:the major peak is in Late Paleozoic (259~308Ma) of Hercynian period, followed by the peak in Paleoproterozoic (1.74~2.18Ga) and the peak from Early Paleoproterozoic to Neoarchaean (2.39~2.58Ga). Detrital zircon ages of Hercynian period are close to ages of Langshan large-scale exposed magmatic rocks, the ages of Paleoproterozoic to Neoarchaean are similar in features to the ages of khondalite belt. The sandstone REE distribution characteristics of Jurassic sandstones are similar to those of Hercynian magmatic rocks, Wulashan Group and khondalite belt. Combined with conglomerates and sandstone slices analysis of Shiguai Group, it is held that the Jurassic sedimentation was in a nearsource environment and the provenance was mainly from large-scale Hercynian magmatic rocks in Langshan area. A secondary provenance was derived from khondalite belt in Hetao area. Wulashan Group of Archean, Paleoproterozoic magmatic rocks and Early Mid Triassic magmatic rocks probably provided a small part of the provenance. According to the youngest detrital zircon age of 243Ma in Middle Triassic, the sedimentary age of the strata as Early Middle Jurassic is appropriate, which is in accordance with the fact of total lack of Triassic strata in Langshan area. Based on the provenance analysis, it is concluded that there existed two source areas of north and south on both sides of the Jurassic strata, with the main provenance from Langshan uplift in the north and the secondary provenance from Hetao uplift in the south. There are some differences between different parts of the provenance. |
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| Keywords: | Jurassic U-Pb ages of detrital zircons sedimentary provenance Hercynian magmatic rocks khondalite belt |
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