| 内蒙古温都尔庙地区温都尔庙群的形成环境和构造意义 |
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| 引用本文： | 吴泰然,张臣.内蒙古温都尔庙地区温都尔庙群的形成环境和构造意义[J].高校地质学报,1998,4(2):168-176. |
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| 作者姓名： | 吴泰然 张臣 |
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| 作者单位： | 北京大学地质学系 |
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| 摘 要： | 内蒙古温都尔庙地区有一套统称为温都尔庙群的变质岩系，该岩系主要由两种不同的岩石组合组成：一套是出露于乌兰沟一带的浅变质岩系，主要由变玄武岩、硅质岩、火山碎屑岩、碎屑岩组成的基性火山岩－碎屑岩组合；另一套是出露于德言其庙一带的深变质岩系，主要由斜长角并岩、斜长片麻岩组成。这两套岩石组合在变形变质、岩石化学和形成环境等方面都有很大的差异，前者主要表面出弧后盆地的特征，后者则是拉张过程中板底垫托的产物，它们分别代表了华北板块北缘中元古代不同构造演化阶段的产物。
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| 关 键 词： | 内蒙古 温都尔庙群 岩石组合 形成环境 构造意义 |
| 收稿时间： | 1998-06-20 |
| 修稿时间： | 1998-06-20 |
TECTONIC SETTINGS OF ONDOR SUM GROUP AND ITS TECTONIC INTERPRETATION IN ONDOR SUM REGION,INNER MONGOLIA |
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| Wu Tai-ran,Zhang Chen,Wan Ji-hu.TECTONIC SETTINGS OF ONDOR SUM GROUP AND ITS TECTONIC INTERPRETATION IN ONDOR SUM REGION,INNER MONGOLIA[J].Geological Journal of China Universities,1998,4(2):168-176. |
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| Authors: | Wu Tai-ran Zhang Chen Wan Ji-hu |
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| Institution: | Geological Department of Peking University, Beijing 100871 |
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| Abstract: | There is a set of metamorphic rocks in Ondor Sum region, Nei Mongol, which was named as Ondor Sum Group and its age was considered as Paleozoic before. Tow major assemblages of the Group can be recognized. One is outcropping at Wulangou and consists of metamorphic pillow basalt, clastic rocks, silicalite and other epimetamorphic rocks. The other is outcropping at Deyanqimiao and consists of plagioamphibole, plagiogneiss and other hypometamorphic rocks. The assemblages are different from each other in metamorphism, deformation and petrologic chemistry as we1l as the tectonic settings. The results of this study demonstrated that the volcano-elastic assemblage was formed in back-arc basin, and the hypometamorphic assemblage was the underplatting product during extention in the region. Recognization of the DNO assemblages has an important significance for the tectonic evolution of the northern margin of North China Plate. According to the recent isotopic chronological data, the ages of two assemblages are all Neo-Proterozoic. The Sm-Nd isotopic age of the volcano-elastic assemblage is 807～961Ma, and the hypometamorphic assemblage is about 638Ma. The rifting began in the Meso-Proterozoic at northern margin of North Chins Plate. At the beginning of the Neo-Proterozoic, there was a series of island arcs separated from the North China Plate and back-are basin occurred at the same time. The volcano—elastic assemblage were formed in this period. Another extensional cycle began at the end of the Neo-Proterozoic. The hypometamorphic assemblages were formed in the magmatic passive margin during underplating. Since the major assemblages of the Ondor Sum Group are the products of different stages in tectonic evolution of North China Plate in Neo-Proterozoic, the tectonic evolution in the Paleozoic must be reconsidered. |
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| Keywords: | Inner Mongolia Ondor Sum Group different assemblage tectonic setting |
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