| 内蒙古北山小红山岩组变形特征及地质意义 |
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| 作者姓名： | 张兆琪 潘永胜 卫彦升 段春森 刘畅 李奎芳 |
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| 作者单位： | 山西省地质调查院,太原 030001 |
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| 基金项目： | 中国地质调查局“内蒙古1:5万额勒斯图浑迪等幅区域地质矿产调查”项目资助 |
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| 摘 要： | 为了研究红石山—百合山—蓬勃山古生代构造带(蛇绿岩带)物质组成和变形特征,利用数字填图方法,在内蒙古北山地区大红山一带,开展1:5万区域地质调查。发现大红山南出露一套变质基底,主要岩石组合为一套海相细碎屑岩夹中基性火山岩及磁铁石英岩组合,以含硅铁建造及变质基性火山岩为特征。该岩石组合无底无顶,变形变质强烈,分不出层序,故称之为小红山岩组。各类中低级变质岩说明变质作用达到了高绿片岩—低角闪岩相。该组北部被上石炭统白山组角度不整合覆盖,南部被早泥盆世、晚石炭世侵入岩侵入。区内出露面积约140 km2,厚约2 890 m。明显有4次变形: 前3次变形为韧性变形,形成了透入性面理S1、大型褶皱、韧性剪切带等构造形迹; 后一次变形以脆性变形为特征,形成了较大规模的断层带。小红山岩组多期次变形、变质说明了红石山—百合山—蓬勃山古生代构造带(蛇绿岩带)确实存在,并经历了多期次变形和变质。
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| 关 键 词： | 变形 构造形迹 小红山岩组 北山地区 |
| 收稿时间： | 2017-09-05 |
Deformation characteristics and geological significance of Xiaohongshan formation in Beishan Area,Inner Mongolia |
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| Authors: | ZHANG Zhaoqi PAN Yongsheng WEI Yansheng DUAN Chunsen LIU Chang LI Kuifang |
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| Institution: | Shanxi Institute of Geological Survey, Taiyuan 030001, China |
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| Abstract: | In order to investigate the composition and deformation characteristics of the Hongshishan-Baiheshan-Pengboshan Paleozoic tectonic belt (ophiolite belt), using the digital geological mapping, the authors have carried out the 1:50 000 regional geological survey in Dahongshan of Beishan Area, Inner Mongolia. Through the survey, a suit of metamorphic basement was found in the south of Dahongshan, and its main rock assemblage is marine fine clastic rock with intermediate-basic volcanic rock and magnetite quartzite rock, which is characterized by ferrosilicic formation and metamorphic basic volcanic rock. The rock assemblage without bottom and top, has intensive metamorphism and deformation, and its sequences can’t be separated. So the rock assemblage is named as Xiaohongshan formation. The low and medium grade metamorphic rock indicates that the metamorphism reaches high green schist facies to low amphibolite facies. The north of the formation is covered by the angular unconformity of Upper Carboniferous Baishan Formation, and the south is intruded by the Early Devonian and Late Carboniferous intrusive rock. The outcropping area of the formation is about 140 km2 in the study area, and the thickness is about 2 890 m. There are four obvious deformations. The former three are ductile deformation, which form penetrative foliation S1, large-scale folds and ductile shear zone. The last deformation is characterized by brittle deformation and forms some large-scale faults. The multi-stage metamorphism and deformation of Xiaohongshan formation proves that the Hongshishan-Baiheshan-Pengboshan Paleozoic tectonic belt (ophiolite belt) existed and went through multi-stage metamorphism and deformation. |
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| Keywords: | deformation tectonic traces Xiaohongshan formation Beishan Area |
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