| 滇西金沙江-红河构造带鲁甸始新世煌斑岩成因及动力学背景 |
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| 引用本文： | 贺娟,王启宇,闫国川.滇西金沙江-红河构造带鲁甸始新世煌斑岩成因及动力学背景[J].地球科学,2018,43(8):2586-2599. |
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| 作者姓名： | 贺娟 王启宇 闫国川 |
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| 作者单位： | 1.中国地质调查局成都地质调查中心, 四川成都 610081 |
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| 基金项目： | 国家重点研究发展计划2015CB452601中国地质调查局项目DD20160016国家自然科学基金项目41603038 |
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| 摘 要： | 前人对金沙江-红河构造带上的煌斑岩研究工作主要集中在南段哀牢山地区.对构造带中段鲁甸地区新发现的煌斑岩脉进行了锆石U-Pb年代学和全岩地球化学研究.结果表明，煌斑岩形成时代为始新世末期，与滇西新生代富碱斑岩高峰期一致.鲁甸煌斑岩具有高钾、富碱、高Mg#，富集大离子亲石元素（LILE）和轻稀土元素（LREE），亏损高场强元素（HFSE，尤其是Ta-Nb-Ti）的特征.其岩浆源区为受俯冲流体和熔体交代的岩石圈地幔，源区组分为含金云母的尖晶石相方辉橄榄岩.结合同期的镁铁质火山岩和富碱斑岩研究成果，滇西区域的岩石圈地幔富集过程可能为元古宙时期与罗迪尼亚超大陆聚合相关的俯冲作用.始新世时期，在印度和亚洲大陆碰撞过程中，金沙江-红河构造带的富集岩石圈地幔发生拆沉或对流减薄，软流圈物质上涌，引发富集的岩石圈地幔部分熔融，形成本期煌斑岩岩浆作用.
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| 关 键 词： | 煌斑岩 金沙江-红河构造带 富集地幔 岩石成因 鲁甸 滇西 地质年代学 地球化学 |
| 收稿时间： | 2018-05-30 |
Genesis and Geodynamic Settings of the Eocene Lamprophyres from Jinshajiang-Red River Tectonic Belt,Ludian, Western Yunnan Province |
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| Abstract: | Researches on the lamprophyres from the Jinshajiang-Red River tectonic belt are mainly concentrated in the southern Ailaoshan area.The zircon U-Pb geochronology and the whole rock geochemistry of the newly discovered Ludian lamprophyres located in the middle segment of the belt are applied in this paper.Zircon U-Pb dating proves Eocene emplacement age of Ludian lamprophyres, which is consistent with the peak age of the Cenozoic magmatism in the Jingshajiang-Red River alkali-rich intrusion belt.Geochemical data indicate that Ludian lamprophyres have the characteristics of high K2O, high (K2O + Na2O) and Mg#, low TiO2, being enriched in LILE and LREE, depleted in HFSE (especially Ta-Nb-Ti).The source of the Ludian lamprophyres should be the lithosphere mantle which had been enriched by subduction-related fluids and melts, and the source should be phlogopite bearing spinel harzburgite.Combined with the study of coeval mafic lava and felsic intrusion, we put forward that the mantle in western Yunnan might have been enriched by the Protozoic subduction related to the assembly of the Rodinia supercontinent.In the Eocene, following the collision between Indian and Asia, the continental lithosphere in the Jingshajiang-Red River tectonic belt underwent convective thinning or delamination, which induced rising of the asthenosphere, and then partial melting of the enriched lithosphere mantle which generated the lamprophyre melt. |
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