| 鄂尔多斯盆地西南缘下-中侏罗统碎屑锆石U-Pb年代学及其地质意义 |
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| 引用本文： | 郭佩,刘池洋,韩鹏,王建强,邓煜,王文青.鄂尔多斯盆地西南缘下-中侏罗统碎屑锆石U-Pb年代学及其地质意义[J].大地构造与成矿学,2017,41(5):892-907. |
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| 作者姓名： | 郭佩 刘池洋 韩鹏 王建强 邓煜 王文青 |
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| 作者单位： | 1. 西北大学地质学系,大陆动力学国家重点实验室,陕西西安710069;2. 中国石油长庆油田公司勘探开发研究院,陕西西安710018;低渗透油气田勘探开发国家工程实验室,陕西西安710018 |
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| 基金项目： | 国家自然科学基金重点项目，中国地质调查局项目，国家科技重大专项 |
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| 摘 要： | 改造盆地主要发育时期原始沉积边界的厘定具有重要的油气地质和区域构造意义。物源分析是厘定盆地原始沉积边界的重要内容和有效手段。对鄂尔多斯盆地西南缘邻区下-中侏罗统砂岩碎屑锆石LA-ICP-MS U-Pb年龄谱的研究,为厘定盆地西南沉积边界提供了新的依据。盆地西南缘六盘山地区上流水和炭山剖面的下-中侏罗统延安组砂岩碎屑锆石年龄谱较为相似,而与靖远地区红会四矿剖面同期地层的碎屑锆石年龄谱相差较大。将这三区碎屑锆石的年龄谱与周邻构造单元结晶岩体的年龄对比表明,早-中侏罗世期间靖远地区沉积物来源于西南侧的祁连造山带,而六盘山地区沉积物来源于西北侧阿拉善地块和北侧的华北克拉通北缘。对物源、地层厚度、岩性、煤层特征等差异的综合研究认为,这两个地区在早-中侏罗世期间属不同沉积域,鄂尔多斯盆地的西南沉积边界为海原断裂带。
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| 关 键 词： | 鄂尔多斯盆地西南缘 下-中侏罗统 碎屑锆石 物源分析 沉积边界 |
Geochronology of Detrital Zircon from the Lower-Middle Jurassic Strata in the Southwestern Ordos Basin,China,and its Geological Significance |
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| GUO Pei,LIU Chiyang,HAN Peng,WANG Jianqiang,DENG Yu,WANG Wenqing.Geochronology of Detrital Zircon from the Lower-Middle Jurassic Strata in the Southwestern Ordos Basin,China,and its Geological Significance[J].Geotectonica et Metallogenia,2017,41(5):892-907. |
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| Authors: | GUO Pei LIU Chiyang HAN Peng WANG Jianqiang DENG Yu WANG Wenqing |
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| Abstract: | Delineation of the original sedimentary boundaries in deformed basins has great significance in both petroleum exploration and tectonic geology.Provenance analysis through detrital zircon U-Pb dating is an important and relatively effective approach.In this paper,240 zircon grains of three sandstone samples collected from the Lower-Middle Jurassic strata in the southwestern Ordos Basin have been analyzed to define the Jurassic southwestern boundary of the Ordos Basin.Two samples were collected from the Liupanshan area and one sample from the Jingyuan area,the latter is in margin of the southwestern Ordos Basin and is critical for boundary division.Results show that detrital zircons in the two Liupanshan samples have similar age populations which are distinct from those of the Jingyuan sample,indicative of different origins.Matching the detrital zircon age populations of the Lower-Middle Jurassic sandstones with the crystallization ages of the potential source rocks in the adjacent tectonic units,we argue that during the Early-Middle Jurassic the North Qilian Orogenic Belt to the southwest was the main source for the sediments in the Jingyuan area,while the Alax Block to the northwest and the northern margin of North China Craton to the north were the main sources for the sediments in the Liupanshan area.Based on the provenance differences,with further distinct contrasts in strata thickness,lithological characters and coal seam distribution between the two areas,we therefore conclude that during the Early-Middle Jurassic the Jingyuan and Liupanshan areas were not in the same sedimentary domains,and the Jurassic sedimentary boundary of the southwestern Ordos Basin was the Haiyuan Fault. |
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| Keywords: | southwestern Ordos Basin Lower-Middle Jurassic detrital zircon provenance analyses sedimentary boundary |
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