邓科,袁仁华,董玉杰,张泽国,陈守关,辛堂.西藏刘琼村北始新世石英闪长岩的成因及其地质意义[J].地质找矿论丛,2022,37(4):447-456
西藏刘琼村北始新世石英闪长岩的成因及其地质意义
Genesis and geological significance of Eocene quartz diorite in north of Liuqiong village, Tibet
投稿时间:2022-03-25  
DOI:10.6053/j.issn.1001-1412.2022.04.007
中文关键词:  石英闪长岩  锆石U-Pb定年  Lu-Hf同位素  亏损地幔  同碰撞构造  西藏
英文关键词:quartz diorite  zircon U-Pb dating  Lu-Hf isotope  the depleted mantle  collisional structure  Tibet
基金项目:中国地质调查局“冈底斯—喜马拉雅铜矿资源基地调查”项目(编号:DD20160015-09)资助。
作者单位E-mail
邓科 西藏自治区地质矿产勘查开发局第五地质大队, 青海 格尔木 816099  
袁仁华 西藏自治区地质矿产勘查开发局第五地质大队, 青海 格尔木 816099 370496412@qq.com 
董玉杰 西藏自治区地质矿产勘查开发局第五地质大队, 青海 格尔木 816099  
张泽国 西藏自治区地质矿产勘查开发局第五地质大队, 青海 格尔木 816099  
陈守关 西藏自治区地质矿产勘查开发局第五地质大队, 青海 格尔木 816099  
辛堂 西藏自治区地质矿产勘查开发局第五地质大队, 青海 格尔木 816099  
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中文摘要:
      本文以西藏刘琼村北始新世石英闪长岩为研究对象,通过岩石学、岩石地球化学方法及锆石同位素年代测定,分析了岩浆起源、岩石成因及形成的构造环境。LA-ICP-MS锆石U-Pb定年结果显示,岩体形成于始新世(53.74Ma~55.94Ma)。岩石属准铝质钙碱性系列,富集大离子亲石元素(K、U、Rb、Ba)和轻稀土(LREE),亏损高场强元素(Nb、Ta、Ti、Zr)和重稀土(HREE),无明显Eu异常。锆石εHf(t)值为+10~+14.9,单阶式Hf模式年龄(tDM1)集中在192.9~341.8之间,表明岩浆源区来自于亏损地幔中新增生出来的年轻地壳,具S型花岗岩地球化学特征,推断其形成于同碰撞构造环境,表明始新世时期冈底斯南缘处于新特提斯洋与拉萨地块同碰撞构造环境背景之下。
英文摘要:
      An Eocene quartz dioxide body occurs in north of Liuqiong village. It is studied in respects of petrology, petro geochemistry and isotropic chronology to discuss source of its magma, genesis and tectonic setting. The U-Pb dating of zircon LA-ICP-MS is 53.74 Ma-55.94 Ma corresponding to Eocene. It belongs to quasi-aluminous calc-alkaline series enriched in large-ion lithophile elements(K, U, Rb, Ba) and LREE, depleted in high field strong elements(Nb, Ta, Ti, Zr) and HREE without EU depletion.εHf(t) value of zircon is +10-+14.9, and the single-stage Hf model age (tDM1) is concentrated between 192.9-341.8 indicating that the magma source region is the newly accredited young crust in the depleted mantle and the diorite is characteristic of S type granite. It is infered that the diorite is formed under the syn-collisional environment and in Eocene the South margin of Gangdise continent is under collisional setting of the new Tethys and Lhasa block.
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