Discovery of the Yunzhug sheeted dike swarm in northern Tibet, China-Evidence for seafloor spreading
Discovery of the Yunzhug sheeted dike swarm in northern Tibet, China-Evidence for seafloor spreading
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发表时间：
2005
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通讯作者：
Wang Yong-sheng;Qu Yong-gui;Wang Zhongheng;Zheng Chun-zi;Xie Yuan-he;Sun Zhonggang;Zhang Ningke
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作者：
Wang Yong-sheng;Qu Yong-gui;Wang Zhongheng;Zheng Chun-zi;Xie Yuan-he;Sun Zhonggang;Zhang Ningke
云珠席状岩墙群位于藏北班公湖-怒江缝合带与雅鲁藏布江缝合带之间。其规模之大、结构之完整，在中国身上实属罕见。席状岩墙群由变辉绿岩、变辉长岩和变辉长斑岩脉组成，向上与枕状玄武岩具有分级侵入性接触关系。冷凝边缘在蜂群的一侧或两侧发育。其化学组成以CaO、Al_2O_3、MgO、FeO、Fe_2O_3含量较高，而TiO_2、P_2O_5含量较低为特征。它们属于亚碱性系列。微量元素主要表现为MORB特征，部分分解图中表现为MORB和IAT的过渡特征，推测可能来自弧后盆地环境。根据岩墙群的放射虫硅质岩时代和同位素年龄，确定云珠席状岩墙群可能形成于中侏罗世-早白垩世。这一发现为中特提斯洋期海底扩张提供了新的证据。
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.