| 岳龙,王敏,曾昌兴,陈仁,贺永忠,易成兴.西藏改则县鱼鳞山地区新近系鱼鳞山组火山岩特征[J].贵州地质,2021,38(1):35-42, 64 |
| 西藏改则县鱼鳞山地区新近系鱼鳞山组火山岩特征 |
| Characteristics of Volcanic Rocks of Neogene Yulinshan Formation in Yulishan Area, Gaize of Tibet |
| 投稿时间：2020-04-21 |
| DOI： |
| 中文关键词: 鱼鳞山组 火山岩 岩石学 地球化学 西藏 |
| 英文关键词:Yulinshan formation Volcanic rocks Retrology Geochemistry Tibet |
| 基金项目: |
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| 中文摘要: |
| 笔者在参与西藏1∶25万加错幅区域地质调查项目的基础上，对西藏鱼鳞山地区鱼鳞山组火山岩进行进一步岩石学、岩石地球化学分析数据挖掘及再研究。研究表明该组由火山碎屑岩及火山熔岩组成至少具有三个韵律；主量元素表明其为高碱富钾的基—中性岩类，属钾玄岩系列—高钾质系列；稀土元素中轻重稀土的∑LREE/ ∑HREE比值和(La/Yb)N比值分别为16441939和73048418，火山岩轻重稀土的分馏程度较大；微量元素中高场强元素Nb、Ta、Zr、Hf、Ti相对于相邻大离子亲石元素明显亏损，且Sr同样表现出亏损态势。结合稀土及微量元素特征，鱼鳞山组火山岩为板内裂谷幔源玄武质岩浆演化而来，仅伴有少量的地壳混染，为喜山造山运动中板内应力松驰阶段之产物，近东西向昆楚克错断裂在喜山期复活为岩浆活动提供了通道。 |
| 英文摘要: |
| On the basis of the Tibet 1:250,000 Jiacuo regional geological survey project and the results re-port worked in, further petrological and lithogeochemical analysis was carried out , data mining and re-research on Yulinshan formation volcanic rocks in Yulinshan area, Tibet. The study shows that this formation consisting of tephra and volcanic lava has at least three rhythms; bulk elements show that it is a base - neutral rock with high alkali and rich potassium, belonging to shoshonite series - high potassium series; the ratios of ∑LREE/∑HREE and (La/Yb)N of light and heavy rare earth in rare earth elements are 16.4419.39 and 73.0484.18 respectively, and the fractionation degree of light and heavy rare earth in volcanic rocks is relatively large; the high field strength elements Nb, Ta, Zr, Hf and Ti in trace elements are obviously deficient compared with the adjacent large ion lithophile elements, and Sr also shows a deficit situation. Combined with the characteristics of rare earth and trace elements, the volcanic rocks of Yulinshan formation evolved from mantle-derived basaltic magma from intraplate rift valley, accompanied by only a small amount of crustal contamination, which was the product of internal plate stress relaxation stage in Himalayan orogeny. It cracked east to west towards Kunchu Kecuo, providing a channel for magmatism in Himalayan revival. |
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