摘要
为了全面研究阿拉尔岩体与可可托海地区伟晶岩脉群在成因上的关系,笔者系统分析阿拉尔岩体西部阿热散一带含绿柱石伟晶岩脉中锆石U-Pb同位素年龄、地球化学、Hf同位素特征。结果显示:伟晶岩脉锆石^(206)Pb/^(238)U加权平均年龄为(203.9±2.2)Ma,地球化学特征表现为高Si、低Ti、富Al、富碱,富集大离子亲石元素Rb、Th、U和稀土元素La、Ce、Nd、Sm,亏损Ba、Nb、Ta、Zr、Hf、Sr、P、Ti,属于典型的低Ba、Sr岩石,锆石同位素^(176)Hf/^(177)Hf值为0.282714~0.282749,ε_(Hf)(t)值为+2.56~+3.65,tDMC模式年龄为852~912 Ma,与阿拉尔岩体具有形成时代的一致性,地球化学特征的相关性,^(176)Hf/^(177)Hf值与ε_(Hf)(t)值的相似性,表明两者具有密切的成因关系。结合区域资料认为,中生代稀有金属矿化伟晶岩脉与阿拉尔岩体所代表的岩浆活动可能均起源于前寒武纪变质砂岩及变质泥岩等地壳物质部分熔融,并发生了显著地结晶分异作用。
In order to comprehensively study the genetic relationship between Aral Rock Mass and the Pegmatite Vein group in Koktokay area,this work systematically analyzed the Zircon U-Pb isotopic age,geochemistry and Hf isotopic characteristics of the Be bearing pegmatite vein in the Ahersan area of the western Aral Rock Mass.The results show that the Zircon ^(206)Pb/^(238)U weighted average age of the pegmatite vein is(203.9±2.2)Ma.Its geochemical characteristics are high silicon,low titanium,rich aluminum,rich alkali,rich in large ion lithophile elements Rb,Th,U and rare earth elements La,Ce,Nd,Sm,and depleted in Ba,Nb,Ta,Zr,Hf,Sr,P,Ti.It belongs to typical low Ba,Sr rocks.The zircon isotope ^(176)Hf/^(177)Hf values range from 0.282714 to 0.282749,The range ofε_(Hf)(t)value is+2.56~+3.65,the age of tDM C model is 852~912 Ma.the similarity of Zircon U-Pb isotopic age,the correlation of geochemical characteristics,the similarity of ^(176)Hf/^(177)Hf andε_(Hf)(t)values,indicates that they have a close genetic relationship.Based on the regional data,it is believed that the magmatic activities represented by the Mesozoic rare metal mineralized pegmatite vein and Aral Rock Mass are may originate from the partial melting of crustal materials such as Precambrian metasandstone and metamorphic mudstone,and significant crystallization differentiation occurred.
作者
蔺新望
王星
张亚峰
赵端昌
赵江林
刘坤
LIN Xinwang;WANG Xing;ZHANG Yafeng;ZHAO Duanchang;ZHAO Jianglin;LIU Kun(Shaanxi Mineral Resources and Geological Survey,Xi’an 710068,Shaanxi,China;Shaanxi Institute of Geological Survey,Xi’an 710054,Shaanxi,China)
出处
《西北地质》
CAS
CSCD
北大核心
2023年第4期75-90,共16页
Northwestern Geology
基金
陕西省公益性地质调查项目“陕西省南秦岭成矿带佛坪隆起南缘茅坪地区基础地质调查”(202102)
新疆地勘基金中心项目“新疆富蕴县阿拉一带1∶5万L45E003023等五幅区域地质调查”(A16-1-LQ01)
中国地质调查局项目“阿尔泰成矿带喀纳斯和东准地区地质矿产调查”(DD20160006)联合资助。
