| 密文天,罗宇航,李雪华,叶翔飞.洞错盆地蛇绿岩地球化学特征及大地构造意义[J].地质找矿论丛,2023,38(1):87-103 |
| 洞错盆地蛇绿岩地球化学特征及大地构造意义 |
| Geochemical characteristics of ophiolite in Dongcuo basin and the geotectonic signoficance |
| 投稿时间：2022-05-10 |
| DOI：10.6053/j.issn.1001-1412.2023.01.011 |
| 中文关键词: 蛇绿岩 地球化学 洞错盆地 西藏 |
| 英文关键词:Ophiolite geochemistry Dongcho basin Tibet |
| 基金项目:甘肃省西部矿产资源重点实验室开放基金（编号：MRWCGS2019-01）、内蒙古教育科学规划课题（编号：NGJGH2020058）、内蒙古工业大学地质类系列课程优秀教学团队、内蒙古工业大学研究生教改项目（编号：YJG2020014）及校教改项目（编号：2020115）联合资助。 |
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| 中文摘要: |
| 本文以改则的洞错盆地蛇绿岩为研究对象，开展了洞错盆地蛇绿岩的岩石学、岩相学及地球化学方面的研究工作。结果表明：地幔橄榄岩以方辉橄榄岩为主，为烟斗型稀土元素配分型式；形成于熔融程度较高的地幔残余物质，具有Nb、Ta负异常。辉绿岩稀土元素配分型式与N-MORB类似，其稀土元素来自亏损的软流圈地幔；Ta、Ti、Y等高场强元素分布特征与N-MORB相似；辉绿岩既有MORB特征又有IAT特征，在洋内弧后盆地扩张环境中形成。辉长岩稀土配分曲线与N-MORB的类似；微量元素中K、Rb、Ba等富集，Nb、Ta亏损，有岛弧火山岩的特征，与典型的N-MORB特征有区别；既有MORB特征，也显示了俯冲带物质的参与，为消减带上弧后盆地次级扩张产生的新洋壳。因此，洞错蛇绿岩为SSZ型蛇绿岩。 |
| 英文摘要: |
| This paper deals with petrology, petrography and geochemistry of ophiolite in Dongcuo basin. The mantle Peridotite is mainly harzburgite with tobacco pipe-like REE pattern and negative Nb, Ta anomaly. The harzburgite is derived from highly melted residual mantle materials. REE of the diabase come from depleted astheno-sphere mantle and the distribution pattern as well as the distribution pattern of high field strength elements of Ta, Ti, Y etc. is similar to that of N-MORB. The diabase shares characteristics of MORB and IAT suggesting that it is formed in the spreading environment of intra-ocean back basin. REE pattern of the gabbro is similar to that of N-MORB with K, Rb and Ba enrichment and Nb, Ta depletion sharing characteristics of island arc volcanic rock. The pattern differs from typical N-MORB and suggests not only characteristics of MORB but also incorperation of the subduction materials. The gabbro should be new ocean crust generated by sub-spreading of back arc basin on the subduction zone. The ophiolite in Dongcuo basin belongs to SSZ type ophiolite. |
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