| 藏北永珠席状岩墙群的发现--海底扩张的证据 |
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| 引用本文： | 王永胜,曲永贵,王忠恒,郑春子,谢元和,孙忠刚,张宁克.藏北永珠席状岩墙群的发现--海底扩张的证据[J].地质通报,2005,24(12):1150-1156. |
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| 作者姓名： | 王永胜 曲永贵 王忠恒 郑春子 谢元和 孙忠刚 张宁克 |
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| 作者单位： | 1. 吉林省地质调查院,吉林,长春,130061
2. 吉林省国土资源厅科技档案馆,吉林,长春,130061 |
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| 摘 要： | 新发现的永珠席状岩墙群位于西藏北部班公错一怒江缝合带与雅鲁藏布江缝合带之间。永珠席状岩墙群规模之大、结构之完整在国内尚属罕见。岩石由蚀变辉绿岩、辉长岩扣辉绿玢岩岩墙组成，向上与枕状玄武岩呈渐变过渡扣侵入接触关系，发育有单侧或双侧冷凝边，具高CaO、Al2O3、MgO、FeO、Fe2O3，低TiO2、P2O5的特点，为亚碱性系列岩石。微量元素主要显示MORB的特征，部分判别图显示MORB扣岛弧拉斑玄武岩（IAT）的过渡特征，推测可能产于弧后盆地环境。依据上覆放射虫硅质岩的时代扣枕状玄武岩、岩墙群同位素年龄，确定永珠席状岩墙群形成的时间可能为中休罗世-早白垩世。这一发现为中特提斯海时期古海底扩张提供了新的证据。
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| 关 键 词： | 永珠席状岩墙群 海底扩张 中休罗世-早白垩世 弧后盆地 西藏北部 |
| 文章编号： | 1671-2552(2005)12-1150-07 |
| 修稿时间： | 2004年11月18 |
Discovery of the Yunzhug sheeted dike swarm in northern Tibet, China-Evidence for seafloor spreading |
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| WANG Yongsheng,QU Yonggui,WANG Zhongheng,ZHENG Chunzi,XIE Yuanhe,SUN Zhonggang,ZHANG Ningke. Jilin Institute of Geological Survey,Changchun,Jilin,Chin,. Scientific and Technological Archives,Jilin Bureau of Land and Resources,Changchun,Jilin,China.Discovery of the Yunzhug sheeted dike swarm in northern Tibet, China-Evidence for seafloor spreading[J].Geologcal Bulletin OF China,2005,24(12):1150-1156. |
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| Authors: | WANG Yongsheng QU Yonggui WANG Zhongheng ZHENG Chunzi XIE Yuanhe SUN Zhonggang ZHANG Ningke Jilin Institute of Geological Survey Changchun Jilin Chin Scientific and Technological Archives Jilin Bureau of Land and Resources Changchun Jilin China |
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| Abstract: | The Yunzhug sheeted dike swarm is located between the Bangong Co-Nujiang suture zone in northern Tibet and Yarlung Zangbo suture zone. Its large scale and complete structure preserved are rarely seen in China. The sheeted dike swarm consists of meta-diabase, meta-gabbro and meta-diabase porphyrite dikes and upward it has gradational and intrusive contact relationships with pillow basalt. The chilled border is developed on one side or two sides of the swarm. Their chemical composition is characterized by high contents of CaO, AI2O3, MgO, FeO and Fe2O3 and low contents of TiO2 and P2O5. They belong to the subalkaline series. The trace elements main manifestation MORB characteristic, manifestation MORB and IAT transition characteristic in the part differentiate diagram, guess may generate from back-arc basin environment. According as the radidarian cherts times and isotope ages of the dike swarm assurance that the Yunzhug sheeted dike swarm may have formed in the Middle Jurassic-Early Cretaceous.This discovery provides new evidence for seafloor spreading in the Meso-Tethys Ocean period. |
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