| 昌宁-孟连缝合带干龙塘-弄巴蛇绿岩地球化学及Sr-Nd-Pb同位素组成研究 |
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| 引用本文： | 赖绍聪,秦江锋,李学军,臧文娟.昌宁-孟连缝合带干龙塘-弄巴蛇绿岩地球化学及Sr-Nd-Pb同位素组成研究[J].岩石学报,2010,26(11):3195-3205. |
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| 作者姓名： | 赖绍聪 秦江锋 李学军 臧文娟 |
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| 作者单位： | 大陆动力学国家重点实验室,西北大学地质学系,西安,710069 |
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| 基金项目： | 本文受国家自然科学基金(40872060)、陕西省教育厅省级重点实验室科研与建设计划项目(08JZ62)和大陆动力学国家重点实验室科技部专项经费联合资助. |
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| 摘 要： | 本文对三江古特提斯昌宁-孟连带中段弄巴-干龙塘蛇绿混杂岩进行了详细的主量、微量元素及Sr-Nd-Pb同位素地球化学研究。结果表明,弄巴玄武岩包括拉斑系列和碱性系列,弄巴拉斑玄武岩具有高TiO2和低K2O的特征,(La/Yb)N介于1.87～2.38之间,岩石的Sr-Nd-Pb同位素组成和典型MORB十分相似,结合岩石较高的Th/Yb和低的Zr/Nb值,可以认为弄巴拉斑玄武岩具有富集型洋脊玄武岩(E-MORB)的特征,可能起源于富集的地幔源区或是亏损地幔源区和地幔柱发生交代作用的结果。弄巴碱性玄武岩具有较高的TiO2(2.38%)和K2O(2.37%)含量,(La/Yb)N=11.19,富集轻稀土,表现出典型的碱性OIB的特征,可能是大洋板内热点浅部熔融的产物。干龙塘拉斑玄武岩具有高TiO2、Mg#,低K2O和亏损轻稀土等特征,表现出N-MORB的地球化学特征,岩石的Sr-Nd-Pb与MORB相似,表明岩石起源于亏损的地幔源区。
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| 关 键 词： | 地球化学 蛇绿岩 Sr-Nd-Pb同位素 昌宁-孟连缝合带 |
| 收稿时间： | 2009/12/9 0:00:00 |
| 修稿时间： | 2010/6/17 0:00:00 |
Geochemistry and Sr-Nd-Pb istopic features of the Ganlongtang-Nongba ophiolite from the Changning-Menglian suture zone |
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| LAI ShaoCong,QIN JiangFeng,LI XueJun and ZANG WenJuan.Geochemistry and Sr-Nd-Pb istopic features of the Ganlongtang-Nongba ophiolite from the Changning-Menglian suture zone[J].Acta Petrologica Sinica,2010,26(11):3195-3205. |
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| Authors: | LAI ShaoCong QIN JiangFeng LI XueJun and ZANG WenJuan |
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| Abstract: | This paper presents the major- and trace elements and Sr-Nd-Pb isotopes of the meta-basalts from the Ganlongtang-Nongba ophiolitic mélange which is situated at the middle part of the Changning-Menglian Paleo-Tethys suture zone. The Nongba basalts are mainly composed of alkaline and tholeiitic basalts. The tholeiitic basalts have high TiO2 and Th/Yb, low K2O and Zr/Nb and depleted light rare earth elements (LREEs), and show(La/Yb)N ratio (1.87~2.38) and Sr-Nd-Pb isotopes similar to those of enriched mid-ocean ridge basalt (E-MORB), suggesting that they may originate from an enriched mantle source or a mixture of depleted asthenosphere mantle and mantle plume. The Nongba alkaline basalts have high TiO2 (2.38%) and K2O (2.37%) and (La/Yb)N (~11), similar to that of the oceanic island basalts (OIB), indicating that they were derived from a hot spot through the oceanic crust. The Ganlongtang tholeiitic basalts show typical characteristics of N-MORB in terms of TiO2, Mg#, K2O and LILEs, but have variable Sr-Nd-Pb isotopic compositions probably resulted from crustal contamination. It is proposed that the Changning-Menglian ancient ocean basin experienced a complete growth process from an embryonic to a mature ocean basin. |
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| Keywords: | Geochemistry Ophiolite Sr-Nd-Pb isotopes Changning-Menglian suture zone |
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