| 内蒙古、河北交界区中二叠世三面井期岛弧型陆缘环境 |
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| 引用本文：田树刚,范嘉松,施立志,汪彪.2021.内蒙古、河北交界区中二叠世三面井期岛弧型陆缘环境[J].地球学报,42(4):472-486. |
| DOI：10.3975/cagsb.2021.010403 |
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| 基金项目:国家自然科学基金项目(编号: 41472027);中国地质调查局地质调查项目(编号: DD20160168) |
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| 中文摘要:通过综合研究, 恢复内蒙古、河北交界区中二叠世三面井期古地理环境, 并在三面井组地层研究方面取得显著进展。首先采集三面井和朝海图两剖面出露的安山岩, 进行锆石U-Pb测年, 数据证明它们的喷发时代为中二叠世三面井期。其次在建组剖面附近发现一段\二段界线连续剖面, 并研究界线上滚动球体成因, 证明该界线上下地层沉积连续(整合)。再次, 深入研究各类岩石的成因, 区分火山碎屑岩和安山玢岩, 在研究区确定“喷发中心相”和“近源相”。最后, 结合球枕状沉积构造和火山碎屑生物礁所指示的特定环境, 划分两条代表剖面(三面井村和朝海图)的相变序列, 系统恢复研究区中二叠世三面井期二类岛弧型陆缘环境模式。环境模式由6个古地理单元组成, 即滨岸潮坪、边缘坳陷、陆棚隆起、弧后盆地、火山岛弧和弧前盆地。 |
| 中文关键词:三面井组 火山岛弧 主动陆缘 锆石U-Pb 内蒙古、河北交界区 |
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| Sanmianjingian Stage Conditions of the Island-arc Type Epicontinental Environment in the Hebei–Inner Mongolia Border Area |
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| Abstract:In this study, Sanmianjingian Stage paleo-geographical environments were restored, and some notable progresses were made in stratigraphic investigation, in the Hebei–Inner Mongolia border area. Firstly, some andesite samples were collected along the Sanmianjing section and the Chaohaitu section, and data of the zircon U-Pb isotope test show that the age of andesite belongs to the Sanmianjingian Stage of Middle Permian. Secondly, the continual boundary section and rolling-balls show that the strato-boundary between the 1st Member and the 2nd Member should be conformable, which was discovered near or on the Sanmianjing section. Thirdly, the erupting facies and the near-source facies were distinguished through distinguishing volcaniclastic rocks from volcanic lava. Lastly, in combination with detailed studies of ball-pillow shaped structures and volcaniclastic reefs, two sedimentary facies sequences were recognized separately on the Sanmianjing section and the Chaohaitu section, and two kinds of epicontinental condition models were restored systematically in the study area. Condition models could contain 6 paleo-geographic units, i.e., the sea-shore tidal-flat, the epicontinental depression, the continental shelf upwarp, the back-arc basin, the volcanic island-arc and the fore-arc basin. |
| keywords:Sanmianjing Formation volcanic island-arc active epicontinent zircon U-Pb Hebei–Inner Mongolia border area |
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